essay on dreams don't allow you to sleep

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Why Your Brain Needs to Dream

We often hear stories of people who’ve learned from their dreams or been inspired by them. Think of Paul McCartney’s story of how his hit song “Yesterday” came to him in a dream or of Mendeleev’s dream-inspired construction of the periodic table of elements.

But, while many of us may feel that our dreams have special meaning or a useful purpose, science has been more skeptical of that claim. Instead of being harbingers of creativity or some kind of message from our unconscious, some scientists have considered dreaming to be an unintended consequence of sleep—a byproduct of evolution without benefit.

Sleep itself is a different story. Scientists have known for a while now that shorter sleep is tied to dangerous diseases, like heart disease and stroke . There is mounting evidence that sleep deprivation leads to a higher risk of obesity and Alzheimer’s disease . Large population studies reflect a saddening truth—the shorter your sleep, the shorter your life . Not only that, sleep helps us to hold onto our memories and to learn facts and skills faster, making it important for everyone including infants, students, athletes, pilots, and doctors.

Much of this I outline in my new book, Why We Sleep: Unlocking the Power of Sleep and Dreams , which summarizes the many findings we have about sleep and its function in our lives.

But what about dreaming? Does it also have a purpose?

Recent work in my neuroscience lab and the work of other scientists has shown that dreams may have a very particular function important to our well-being. Here are the two main ways dreams help us.

Dreaming is like overnight therapy

It’s said that time heals all wounds, but my research suggests that time spent in dream sleep is what heals. REM-sleep dreaming appears to take the painful sting out of difficult, even traumatic, emotional episodes experienced during the day, offering emotional resolution when you awake the next morning.

REM sleep is the only time when our brain is completely devoid of the anxiety-triggering molecule noradrenaline. At the same time, key emotional and memory-related structures of the brain are reactivated during REM sleep as we dream. This means that emotional memory reactivation is occurring in a brain free of a key stress chemical, which allows us to re-process upsetting memories in a safer, calmer environment.

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How do we know this is so? In one study in my sleep center, healthy young adult participants were divided into two groups to watch a set of emotion-inducing images while inside an MRI scanner. Twelve hours later, they were shown the same emotional images—but for half the participants, the twelve hours were in the same day, while for the other half the twelve hours were separated by an evening of sleep.

Those who slept in between the two sessions reported a significant decrease in how emotional they felt in response to seeing those images again, and their MRI scans showed a significant reduction in reactivity in the amygdala, the emotional center of the brain that creates painful feelings. Moreover, there was a reengagement of the rational prefrontal cortex of the brain after sleep that helped maintain a dampening influence on emotional reactivity. In contrast, those who remained awake across the day showed no such dissolving of emotional reactivity over time.

That in itself doesn’t say anything about the role of dreaming. But we had recorded each participant’s sleep during the intervening night between the two test sessions, and we found that specific brain activity that reflected a drop in stress-related brain chemistry during the dream state determined the success of overnight therapy from one individual to the next.

Dreaming has the potential to help people de-escalate emotional reactivity, probably because the emotional content of dreams is paired with a decrease in brain noradrenaline. Support for this idea came from a study done by Murray Raskind on vets with PTSD, who often suffer debilitating nightmares. When given the drug Prazosin—a medication that lowers blood pressure and also acts as a blocker of the brain stress chemical noradrenaline—the vets in his study had fewer nightmares and fewer PTSD symptoms than those given a placebo. Newer studies suggest this effect can be shown in children and adolescents with nightmares, as well, though the research on this is still in its infancy.

The evidence points toward an important function of dreams: to help us take the sting out of our painful emotional experiences during the hours we are asleep, so that we can learn from them and carry on with our lives.

Dreaming enhances creativity and problem-solving

It’s been shown that deep non-REM sleep strengthens individual memories. But REM sleep is when those memories can be fused and blended together in abstract and highly novel ways. During the dreaming state, your brain will cogitate vast swaths of acquired knowledge and then extract overarching rules and commonalties, creating a mindset that can help us divine solutions to previously impenetrable problems.

How do we know dreaming and not just sleep is important to this process?

In one study , we tested this by waking up participants during the night—during both non-REM sleep and dreaming sleep—and gave them very short tests: solving anagram puzzles, where you try to unscramble letters to form a word (e.g., OSEOG = GOOSE). First, participants were tested beforehand, just to familiarize them with the test. Then, we monitored their sleep and woke them up at different points of the night to perform the test. When woken during non-REM sleep, they were not particularly creative—they could solve very few puzzles. But, when we woke up participants during REM sleep, they were able to solve 15-35 percent more puzzles than when they were awake. Not only that, participants woken while dreaming reported that the solution just “popped” into their heads, as if it were effortless.

In another study , I and my colleagues taught participants a series of relational facts—such as, A>B, B>C, C>D, and so on—and tested their understanding by asking them questions (e.g., Is B>D or not? ). Afterwards, we compared their performance on this test before and after a full night’s sleep, and also after they’d had a 60- to 90-minute nap that included REM sleep. Those who’d slept or had a long nap performed much better on this test than when they were awake, as if they’d put together disparate pieces of a jigsaw puzzle in their sleep.

Some may consider this trivial, but it is one of the key operations differentiating your brain from your computer. It also underlies the difference between knowledge (retention of individual facts) and wisdom (knowing what they all mean when you fit them together). The latter seems to be the work of REM-sleep dreaming.

“It’s said that time heals all wounds, but my research suggests that time spent in dream sleep is what heals”

Dreaming improves creative problem solving, too, according to another study . Participants learned to navigate a virtual maze using trial and error and aided by the placement of unique objects—like Christmas trees—at certain junctions in the maze. After this learning session, the group was split in two, with half napping and half watching a video for 90 minutes. Nappers were occasionally awoken to ask about the content of their dreams; those watching a video were also asked about thoughts going through their minds.

Afterwards, the participants again tried to solve the maze, and those who napped were significantly better at it than those who didn’t, as expected. But the nappers who reported dreaming about the maze were 10 times better at the task than those who napped and didn’t dream about the maze. There’s a reason you’ve never been told to stay awake on a problem.

Looking at the content of these dreams, it was clear that the participants didn’t dream a precise replay of the learning experience while awake. Instead, they were cherry-picking salient fragments of the learning experience and attempting to place them within the catalog of preexisting knowledge. This is how dreaming helps us be more creative.

While the benefits of dreaming are real, too many of us have problems getting a full eight hours of sleep and lose out on these advantages. Alternatively, we may think we’re the exception to the rule—that we’re one of those people who doesn’t happen to need a lot of sleep. But nothing could be further from the truth. Research clearly shows that people who overestimate their ability to get by on less sleep are sadly wrong.

Five ways to enhance your sleep

So how can we be sure to get enough sleep and experience a dream state? While we may be tempted to use sleeping pills to get to sleep, this has been shown to be detrimental to dreaming. Instead of taking pills, here are some simple ways to enhance your sleep:

1. Make sure your room is dark and that you are not looking at bright light sources—i.e., computer screens and cell phones—in the last hour or two before going to bed. You may even want to start dimming lights in your house in the earlier parts of the evening, which helps to stimulate sleepiness.

2. Go to bed and wake up at approximately the same time every day. This helps signal to your body a regular time for sleeping. It’s no use trying to sleep in a lot on weekends. There is no way to make up for regular sleep loss during the week.

3. Keep the temperature in your house cool at night—maybe even cooler than you think it should be, like around 65 degrees. Your body temperature needs to drop at night for sleep, and a lower room temperature helps signal your brain that it’s time to sleep.

4. If you have trouble falling asleep, or wake in the night feeling restless, don’t stay in bed awake. That trains the brain that your bed is not a place for sleeping. Instead, get up and read a book under dim light in a different room. Don’t look at your computer or cell phone. When sleepiness returns, then go back to bed. Or if you don’t want to get out of bed, try meditating. Studies suggest it helps individuals fall asleep faster, and also improves sleep quality.

5. Don’t have caffeine late in the day or an alcohol-infused nightcap. Both of these interfere with sleep—either keeping you awake or stimulating frequent wake-ups during the night.

Sleep is the single most effective thing we can do to rest our brain and physical health each day. Atop of sleep, dreaming provides essential emotional first aid and a unique form of informational alchemy. If we wish to be as healthy, happy, and creative as possible, these are facts well worth waking up to.

About the Author

Matthew Walker

Matthew Walker is a professor of psychology and neuroscience at the University of California, Berkeley, and the director of the university’s Center for Human Sleep Science .

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Dreams and Dreaming

Dreams and dreaming have been discussed in diverse areas of philosophy ranging from epistemology to ethics, ontology, and more recently philosophy of mind and cognitive science. This entry provides an overview of major themes in the philosophy of sleep and dreaming, with a focus on Western analytic philosophy, and discusses relevant scientific findings.

1.1 Cartesian dream skepticism

1.2 earlier discussions of dream skepticism and why descartes’ version is special, 1.3 dreaming and other skeptical scenarios, 1.4 descartes’ solution to the dream problem and real-world dreams, 2.1 are dreams experiences, 2.2 dreams as instantaneous memory insertions, 2.3 empirical evidence on the question of dream experience, 2.4 dreams and hallucinations, 2.5 dreams and illusions, 2.6 dreams as imaginative experiences, 2.7 dreaming and waking mind wandering, 2.8 the problem of dream belief, 3.1 dreaming as a model system and test case for consciousness research, 3.2 dreams, psychosis, and delusions, 3.3 beyond dreams: dreamless sleep experience and the concepts of sleep, waking, and consciousness, 4. dreaming and the self, 5. immorality and moral responsibility in dreams, 6.1 the meaning of dreams, 6.2 the functions of dreaming, 7. conclusions, other internet resources, related entries, 1. dreams and epistemology.

Dream skepticism has traditionally been the most famous and widely discussed philosophical problem raised by dreaming (see Williams 1978; Stroud 1984). In the Meditations , Descartes uses dreams to motivate skepticism about sensory-based beliefs about the external world and his own bodily existence. He notes that sensory experience can also lead us astray in commonplace sensory illusions such as seeing things as too big or small. But he does not think such cases justify general doubts about the reliability of sensory perception: by taking a closer look at an object seen under suboptimal conditions, we can easily avoid deception. By contrast, dreams suggest that even in a seemingly best-case scenario of sensory perception (Stroud 1984), deception is possible. Even the realistic experience of sitting dressed by the fire and looking at a piece of paper in one’s hands (Descartes 1641: I.5) is something that can, and according to Descartes often does, occur in a dream.

There are different ways of construing the dream argument. A strong reading is that Descartes is trapped in a lifelong dream and none of his experiences have ever been caused by external objects (the Always Dreaming Doubt ; see Newman 2019). A weaker reading is that he is just sometimes dreaming but cannot rule out at any given moment that he is dreaming right now (the Now Dreaming Doubt ; see Newman 2019). This is still epistemologically worrisome: even though some of his sensory-based beliefs might be true, he cannot determine which these are unless he can rule out that he is dreaming. Doubt is thus cast on all of his beliefs, making sensory-based knowledge slip out of reach.

Cartesian-style skeptical arguments have the following form (quoted from Klein 2015):

• If I know that p , then there are no genuine grounds for doubting that p .
• U is a genuine ground for doubting that p .
• Therefore, I do not know that p .

If we apply this to the case of dreaming, we get:

• If I know that I am sitting dressed by the fire, then there are no genuine grounds for doubting that I am really sitting dressed by the fire.
• If I were now dreaming, this would be a genuine ground for doubting that I am sitting dressed by the fire: in dreams, I have often had the realistic experience of sitting dressed by the fire when I was actually lying undressed in bed!
• Therefore, I do not know that I am now sitting dressed by the fire.

Importantly, both strong and weak versions of the dream argument cast doubt only on sensory-based beliefs, but leave other beliefs unscathed. According to Descartes, that 2+3=5 or that a square has no more than 4 sides is knowable even if he is now dreaming:

although, in truth, I should be dreaming, the rule still holds that all which is clearly presented to my intellect is indisputably true. (Descartes 1641: V.15)

By Descartes’ lights, dreams do not undermine our ability to engage in the project of pure, rational enquiry (Frankfurt 1970; but see Broughton 2002).

Dream arguments have been a staple of philosophical skepticism since antiquity and were so well known that in his objections to the Meditations , Hobbes (1641) criticized Descartes for not having come up with a more original argument. Yet, Descartes’ version of the problem, more than any other, has left its mark on the philosophical discussion.

Earlier versions tended to touch upon dreams just briefly and discuss them alongside other examples of sensory deception. For example, in the Theaetetus (157e), Plato has Socrates discuss a defect in perception that is common to

dreams and diseases, including insanity, and everything else that is said to cause illusions of sight and hearing and the other senses.

This leads to the conclusion that knowledge cannot be defined through perception.

Dreams also appear in the canon of standard skeptical arguments used by the Pyrrhonists. Again, dreams and sleep are just one of several conditions (including illness, joy, and sorrow) that cast doubt on the trusthworthiness of sensory perception (Diogenes Laertius, Lives of Eminent Philosophers; Sextus Empiricus, Outlines of Pyrrhonism) .

Augustine ( Against the Academics ; Confessions) thought the dream problem could be contained, arguing that in retrospect, we can distinguish both dreams and illusions from actual perception (Matthew 2005: chapter 8). And Montaigne ( The Apology for Raymond Sebond ) noted that wakefulness itself teems with reveries and illusions, which he thought were even more epistemologically worrisome than nocturnal dreams.

Descartes devoted much more space to the discussion of dreaming and cast it as a unique epistemological threat distinct from both waking illusions and evil genius or brain-in-a-vat-style arguments. His claim that he has often been deceived by his dreams implies he also saw dreaming as a real-world (rather than merely hypothetical) threat.

This is further highlighted by the intimate, first-person style of the Meditations . Their narrator is supposed to exemplify everyone’s epistemic situation, illustrating the typical defects of the human mind. Readers are further drawn in by Descartes’ strategy of moving from commonsense examples towards more sophisticated philosophical claims (Frankfurt 1970). For example, Descartes builds up towards dream skepticism by first considering familiar cases of sensory illusions and then deceptively realistic dreams.

Finally, much attention has been devoted to several dreams Descartes reportedly had as a young man. Some believe these dreams embodied theoretical doubts he developed in the Discourse and Meditations (Baillet 1691; Leibniz 1880: IV; Cole 1992; Keefer 1996). Hacking (2001:252) suggests that for Descartes, dream skepticism was not just a philosophical conundrum but a source of genuine doubt. There is also some discussion about the dream reports’ authenticity (Freud 1940; Cole 1992; Clarke 2006; Browne 1977).

In the Meditations , after discussing the dream argument, Descartes raises the possibility of an omnipotent evil genius determined to deceive us even in our most basic beliefs. Contrary to dream deception, Descartes emphasizes that the evil genius hypothesis is a mere fiction. Still, it radicalizes the dream doubt in two respects. One, where the dream argument left the knowability of certain general truths intact, these are cast in doubt by the evil genius hypothesis . Two, where the dream argument, at least on the weaker reading, involves just temporary deception, the evil genius has us permanently deceived.

One modernized version, the brain-in-a-vat thought experiment, says that if evil scientists placed your brain in a vat and stimulated it just right, your conscious experience would be exactly the same as if you were still an ordinary, embodied human being (Putnam 1981). In the Matrix -trilogy (Chalmers 2005), Matrixers live unbeknownst to themselves in a computer simulation. Unlike the brain-in-a-vat , they have bodies that are kept alive in pods, and flaws in the simulation allow some of them to bend its rules to their advantage.

Unlike dream deception, which is often cast as a regularly recurring actuality (cf. Windt 2011), brain-in-a-vat-style arguments are often thought to be merely logically or nomologically possible. However, there might be good reasons for thinking that we actually live in a computer simulation (Bostrom 2003), and if we lend some credence to radical skeptical scenarios, this may have consequences for how we act (Schwitzgebel 2017).

Even purely hypothetical skeptical scenarios may enhance their psychological force by capitalizing on the analogy with dreams. Clark (2005) argues that the Matrix contains elements of “industrial-strength deception” in which both sensory experience and intellectual functioning are exactly the same as in standard wake-states, whereas other aspects are more similar to the compromised reasoning and bizarre shifts that are the hallmark of dreams.

At the end of the Sixth Meditation , Descartes suggests a solution to the dream problem that is tied to a reassessment of what it is like to dream. Contrary to his remarks in the First Meditation , he notes that dreams are only rarely connected to waking memories and are often discontinuous, as when dream characters suddenly appear or disappear. He then introduces the coherence test:

But when I perceive objects with regard to which I can distinctly determine both the place whence they come, and that in which they are, and the time at which they appear to me, and when, without interruption, I can connect the perception I have of them with the whole of the other parts of my life, I am perfectly sure that what I thus perceive occurs while I am awake and not during sleep. (Meditation VI. 24)

For all practical purposes, he has now found a mark by which dreaming and waking can be distinguished (cf. Meditation I.7), and even if the coherence test is not fail-safe, the threat of dream deception has been averted.

Descartes’ remarks about the discontinuous and ad hoc nature of many dreams are backed up by empirical work on dream bizarreness (see Hobson 1988; Revonsuo & Salmivalli 1995). Still, many of his critics were not convinced this helped his case against the skeptic. Even if Descartes’ revised phenomenological description characterizes most dreams, one might occasionally merely dream of successfully performing the test (Hobbes 1641), and in some dreams, one might seem to have a clear and distinct idea but this impression is false (Bourdin 1641). Both the coherence test and the criterion of clarity and distinctness would then be unreliable.

How considerations of empirical plausibility impact the dream argument continues to be a matter of debate. Grundmann (2002) appeals to scientific dream research to introduce an introspective criterion: when we introspectively notice that we are able to engage in critical reflection, we have good reason to think that we are awake and not dreaming. However, this assumes critical reasoning to be uniformly absent in dreams. If attempts at critical reasoning do occur in dreams and if they generally tend to be corrupted, the introspective criterion might again be problematic (Windt 2011, 2015a). There are also cases in which even after awakening, people mistake what was in fact a dream for reality (Wamsley et al. 2014). At least in certain situations and for some people, dream deception might be a genuine cause of concern (Windt 2015a).

2. The ontology of dreams

In what follows, the term “conscious experience” is used as an umbrella term for the occurrence of sensations, thoughts, impressions, emotions etc. in dreams (cf. Dennett 1976). These are all phenomenal states: there is something it is like to be in these states for the subject of experience (cf. Nagel 1974). To ask about dream experience is to ask whether it is like something to dream while dreaming, and whether what it is like is similar to (or relevantly different from) corresponding waking experiences.

Cartesian dream skepticism depends on a seemingly innocent background assumption: that dreams are conscious experiences. If this is false, then dreams are not deceptive experiences during sleep and we cannot be deceived, while dreaming, about anything at all. Whether dreams are experiences is a major question for the ontology of dreams and closely bound up with dream skepticism.

The most famous argument denying that dreams are experiences was formulated by Norman Malcolm (1956, 1959). Today, his position is commonly rejected as implausible. Still, it set the tone for the analysis of dreaming as a target phenomenon for philosophy of mind.

For Malcolm, the denial of dream experience followed from the conceptual analysis of sleep: “if a person is in any state of consciousness it logically follows that he is not sound asleep” (Malcolm 1956: 21). Following some remarks of Wittgenstein’s (1953: 184; see Chihara 1965 for discussion), Malcolm claimed

the concept of dreaming is derived, not from dreaming, but from descriptions of dreams, i.e., from the familiar phenomenon that we call “telling a dream”. (Malcolm 1959:55)

Malcolm argued that retrospective dream reports are the sole criterion for determining whether a dream occurred and there is no independent way of verifying dream reports. While first-person, past-tense psychological statements (such as “I felt afraid”) can at least in principle be verified by independent observations (but see Canfield 1961; Siegler 1967; Schröder 1997), he argued dream reports (such as “in my dream, I felt afraid”) are governed by different grammars and merely superficially resemble waking reports. In particular, he denied dream reports imply the occurrence of experiences (such as thoughts, feelings, or judgements) in sleep:

If a man had certain thoughts and feelings in a dream it no more follows that he had those thoughts and feelings while asleep, than it follows from his having climbed a mountain in a dream that he climbed a mountain while asleep. (Malcolm 1959/1962: 51–52)

What exactly Malcolm means by “conscious experience” is unclear. Sometimes he seems to be saying that conscious experience is conceptually tied to wakefulness (Malcolm 1956); other times he claims that terms such as mental activity or conscious experience are vague and it is senseless to apply them to sleep and dreams (Malcolm 1959: 52).

Malcolm’s analysis of dreaming has been criticized as assuming an overly strict form of verificationism and a naïve view of language and conceptual change. A particularly counterintuitive consequence of his view is that there can be no observational evidence for the occurrence of dreams in sleep aside from dream reports. This includes behavioral evidence such as sleepwalking or sleeptalking, which he thought showed the person was partially awake; as he also thought dreams occur in sound sleep, such sleep behaviors were largely irrelevant to the investigation of dreaming proper. He also claimed adopting a physiological criterion of dreaming (such as EEG measures of brain activity during sleep) would change the concept of dreaming, which he argued was tied exclusively to dream reporting. This claim was particularly radical as it explicitly targeted the discovery of REM sleep and its association with dreaming (Dement & Kleitman 1957), which is commonly regarded as the beginning of the science of sleep and dreaming. Malcolm’s position was that the very project of a science of dreaming was misguided.

Contra Malcolm, most assume that justification does not depend on strict criteria with the help of which the truth of a statement can be determined with absolute certainty, but “on appeals to the simplicity, plausibility, and predictive adequacy of an explanatory system as a whole” (Chihara & Fodor 1965: 197). In this view, behavioral and/or physiological evidence can be used to verify dream reports (Ayer 1960) and the alleged principled difference between dream reports and other first-person, past-tense psychological sentences (Siegler 1967; Schröder 1997) disappears.

Putnam noted that Malcolm’s analysis of the concept of dreaming relies on the dubious idea that philosophers have access to deep conceptual truths that are hidden to laypeople:

the lexicographer would undoubtedly perceive the logical (or semantical) connection between being a pediatrician and being a doctor, but he would miss the allegedly “logical” character of the connection between dreams and waking impressions. […] this “depth grammar” kind of analyticity (or “logical dependence”) does not exist. (Putnam 1962 [1986]: 306)

Nagel argued that even if one accepts Malcolm’s analysis of the concept of dreaming,

it is a mistake to invest the demonstration that it is impossible to have experiences while asleep with more import than it has. It is an observation about our use of the word “experience”, and no more. It does not imply that nothing goes on in our minds while we dream. (Nagel 1959: 114)

Whether dream thoughts, feelings or beliefs should count as real instances of their kind now becomes an open question, and in any case there is no conceptual contradiction involved in saying one has experiences while asleep and dreaming.

To ask about dream experience is also to ask whether there is something it is like to dream during sleep as opposed to there just being something it is like to remember dreaming after awakening. Dennett’s (1976, 1979) cassette theory says dreams are the product of instantaneous memory insertion at the moment of the awakening, as if a cassette with pre-scripted dreams had been inserted into memory, ready for replay. Dennett claims the cassette theory and the view that dreams are experiences can deal equally well with empirical evidence for instance on the relationship between dreaming and REM sleep. The cassette theory is preferable because it is more parsimonious, positing only an unconscious dream composition process rather than an additional conscious presentation process in sleep. For Dennett, the important point is that it is impossible to distinguish between the two rival theories based on dream recall; the question of dream experience should be settled by independent empirical evidence.

While Dennett shares Malcolm’s skepticism about dream experience, this latter claim is diametrically opposed to Malcolm’s rejection of a science of dreaming. For Dennett, the unreliability of dream recall also is not unique, but exemplifies a broader problem with memory reports: we generally cannot use retrospective recall to distinguish conscious experience from memory insertion (Dennett 1991; see also Emmett 1978).

An earlier and much discussed (Binz 1878; Goblot 1896; Freud 1899; Hall 1981; Kramer 2007:22–24) version of Dennett’s cassette theory goes back to Maury’s (1861) description of a long and complex dream about the French revolution that culminated in his execution at the guillotine, at which point Maury suddenly awoke to find that the headboard had fallen on his neck. Because the dream seemed to systematically build up to this dramatic conclusion, which in turn coincided with a sudden external event, he suggested that such cases were best explained as instantaneous memory insertions experienced at the moment of awakening. Similarly, Gregory (1916) described dreams are psychical explosions occurring at the moment of awakening.

The trustworthiness of dream reports continues to be contentious. Rosen (2013) argues that dream reports are often fabricated and fail to accurately describe experiences occurring during sleep. By contrast, Windt (2013, 2015a) argues that dream reports can at least under certain conditions (such as in laboratory studies, when dreams are reported immediately after awakening by trained participants) be regarded as trustworthy sources of evidence with respect to previous experience during sleep.

Unlike Malcolm, many believe that whether dreams are experiences is an empirical question; and unlike Dennett, the predominant view is that the empirical evidence does indeed support this claim (Flanagan 2000; Metzinger 2003; Revonsuo 2006; Rosen 2013; Windt 2013, 2015a).

A first reason for thinking that dreams are experiences during sleep is the relationship between dreaming and REM (rapid eye movement) sleep. Researchers in the 1950s discovered that sleep is not a uniform state of rest and passivity, but there is a sleep architecture involving different stages of sleep that is relatively stable both within and across individuals (Aserinsky & Kleitman 1953, 1955; Dement & Kleitman 1957). Following sleep onset, periods of non-REM (or NREM) sleep including slow wave sleep (so called because of the presence of characteristic slow-wave, high-voltage EEG activity) are followed by periods of high-frequency, low-voltage activity during REM sleep. EEG measures from REM sleep strongly resemble waking EEG. REM sleep is additionally characterized by rapid eye movements and a near-complete loss of muscle tone (Dement 1999: 27–50; Jouvet 1999).

The alignment between conscious experience on the one hand and wake-like brain activity and muscular paralysis on the other hand would seem to support the experiential status of dreams as well as explain the outward passivity that typically accompanies them. Reports of dreaming are in fact much more frequent following REM (81.9%) than NREM sleep awakenings (43%; Nielsen 2000). REM reports tend to be more elaborate, vivid, and emotionally intense, whereas NREM reports tend to be more thought-like, confused, non-progressive, and repetitive (Hobson et al. 2000). These differences led to the idea that REM sleep is an objective marker of dreaming (Dement & Kleitman 1957; Hobson 1988: 154).

Attempts to identify dreaming with mental activity during REM sleep have not, however, been successful, and many now hold that dreams can occur in all stages of sleep (e.g., Antrobus 1990; Foulkes 1993b; Solms 1997, 2000; Domhoff 2003; Nemeth & Fazekas 2018). In recent years there has been renewed interest in NREM sleep for the study of dreaming (Noreika et al. 2009; Siclari et al. 2013, 2017). This suggests the inference from the physiology of REM sleep to the phenomenology of dreaming is not straightforward.

A second line of evidence comes from lucid dreams, or dreams in which one knows one is dreaming and often has some level of dream control (Voss et al. 2013; Voss & Hobson 2015; Baird et al. 2019). The term lucid dreaming was coined by van Eeden (1913), but Aristotle ( On Dreams ) already noted that one can sometimes be aware while dreaming that one is dreaming.

Scientific evidence that lucid dreaming is real and a genuine sleep phenomenon comes from laboratory studies (Hearne 1978; LaBerge et al. 1981) showing lucid dreamers can use specific, pre-arranged patterns of eye movements (e.g., right-left-right-left) to signal in real-time that they are now lucid and engaging in dream experiments. These signals are clearly identifiable on the EOG and suggest a correspondence between dream-eye movements and real-eye movements (as predicted by the so-called scanning hypothesis ; see Dement & Kleitman 1957; Leclair-Visonneau et al. 2010). Retrospective reports confirm that the dreamer really was lucid and signalled lucidity (Dresler et al. 2012; Stumbrys et al. 2014).

Signal-verified lucid dreams have been used to study muscular activity accompanying body movements in dreams (Erlacher et al. 2003; Dresler et al. 2011), for advanced EEG analysis of brain activity during lucid dreaming (Voss et al. 2009), and imaging studies (Dresler et al. 2011, 2012). Eye signals can also be used to measure the duration of different activities performed in lucid dreams; contrary to the cassette theory, lucid dreams have temporal extension and certain dream actions even seem to take slightly longer than in waking (Erlacher et al. 2014). There have also been attempts to induce lucidity through non-invasive electrical stimulation during sleep (Stumbrys et al. 2013; Voss et al. 2014). The combination of signal-verified lucid dreaming with volitional control over dream content, retrospective report, and objective sleep measures has been proposed to provide controlled conditions for the study of conscious experience in sleep and a new methodology for investigating the relationship between conscious experience and neurophysiological processes (Baird et al.2019).

A third line of evidence (Revonsuo 2006: 77) comes from dream-enactment behavior (Nielsen et al. 2009), most prominently in patients with REM-sleep behavior disorder (RBD; Schenck & Mahowald 1996; Schenck 2005; Leclair-Visonneau et al. 2010). Due to a loss of the muscular atonia that accompanies REM sleep in healthy subjects, these patients show complex, seemingly goal-directed outward behaviors such as running or fighting off an attacker during REM sleep. Retrospective dream reports often match these behaviors, suggesting that patients literally act out their dreams during sleep.

While persuasive, these lines of evidence might not satisfy skeptics about dream experience. They might worry that results from lucid dreaming and dream enactment do not generalize to ordinary, non-lucid dreams; they might also construe alternative explanations that do not require conscious experience in sleep. There are also methodological concerns, for instance about how closely sleep-behaviors actually match dream experience. A key issue is that to support the experiential status of dreams, evidence from sleep polysomnography, signal verified lucid dreams, or sleep behavior requires convergence with retrospective dream reports. This means trusting dream reports is built into any attempt to empirically resolve the question of dream experience – which then invites the familiar skeptical concerns. Again, an anti-skeptical strategy may be to appeal to explanatory considerations. In this view, the convergence of dream reports and objective polysomnographic or behavioral observations is best explained by the assumption that dreams are experiences in sleep, and this assumption is strengthened by further incoming findings. This strategy places dream reports at the center of scientific dream research while avoiding the contentious claim that their trustworthiness, and with it the experiential status of dreams, can be demonstrated conclusively by independent empirical means (Windt 2013, 2015a).

Even where philosophers agree dreams are experiences, they often disagree on how exactly to characterize dreaming relative to wake-state psychological terms. Often, questions about the ontology of dreaming intersect with epistemological issues. Increasingly, they also incorporate empirical findings.

The standard view is that dreams have the same phenomenal character as waking perception in that they seemingly put us in contact with mind-independent objects, yet no such object is actually being perceived. This means dreams count as hallucinations in the philosophical sense (Crane & French 2017; Macpherson 2013). Even if, in a particularly realistic dream, my visual experience was exactly as it would be if I were awake (I could see my bedroom, my hands on the bed sheets, etc.), as long as my eyes were closed during the episode, I would not, literally, be seeing anything.

There is some controversy in the psychological literature about whether dreams should be regarded as hallucinations. Some believe the term hallucination should be reserved for clinical contexts and wake-state pathologies (Aleman & Larøi 2008: 17; but see ffytche 2007; ffytche et al. 2010).

The view that dreams involve hallucinations is implicit in Descartes’ assumption that even when dreaming,

it is certain that I seem to see light, hear a noise, and feel heat; this cannot be false, and this is what in me is properly called perceiving ( sentire ). (Descartes 1641: II.9)

It also lies at the heart of Aristotle’s ( On Dreams ) assumption that dreams result from the movements of the sensory organs that continue even after the original stimulus has ceased. He believed that in the silence of sleep, these residual movements result in vivid sensory imagery that is subjectively indistinguishable from genuine perception (see also Dreisbach 2000; Barbera 2008).

The assumption of phenomenological equivalence between dream and waking experience can also be found in Berkeley’s (1710: I.18) idealist claim that the existence of external bodies is not necessary for the production of vivid, wake-like perceptual experience. Similarly, Russell defended sense-data theory by noting that in dreams,

I have all the experiences that I seem to have; it is only things outside my mind that are not as I believe them to be while I am dreaming. (Russell 1948: 149–150)

Elsewhere, he argued dreams and waking life

must be treated with equal respect; it is only by some reality not merely sensible that dreams can be condemned. (Russell 1914: 69)

Hume was less clear on this matter, proposing that dreams occupy an intermediate position between vivid and largely non-voluntary sensory impressions and ideas, or “the faint images of previous impressions in thinking and reasoning” (Hume 1739: 1.1.1.1). On the one hand, as mere creatures of the mind, Hume wanted to categorize dreams as ideas. On the other hand, he acknowledged that in sleep, “our ideas can approach the vivacity of sensory impressions” (Hume 1739: 1.1.1.1). Dreams do not fit comfortably into Hume’s attempt to draw a dichotomous distinction between impressions, including perception, and ideas, including sensory imagination (Ryle 1949; Waxman 1994; Broughton 2006).

Phenomenologists often focus not so much on the quality of dream imagery as on the overall character of experience, noting that dreams are experienced as reality; as in waking perception, we simply feel present in a world. This also sets dreams apart from waking fantasy and daydreams (Husserl 1904/1905; Uslar 1964; Conrad 1968; Globus 1987: 89.

At its strongest, the hallucination view claims that dreaming and waking experience are identical in both the quality of sensory imagery and their overall, self-in-a-world structure (Revonsuo 2006: 84). This claim is central to the virtual reality metaphor , according to which consciousness itself is dreamlike and waking perception a kind of online hallucination modulated by the senses (Llinás & Ribary 1994; Llinás & Paré 1991; Revonsuo 2006; Metzinger 2003, 2009).

This seems to be empirically supported. Neuroimaging studies (Dang-Vu et al. 2007; Nir & Tononi 2010; Desseilles et al. 2011) show that the predominance of visual and motor imagery as well as strong emotions in dreams is paralleled by high activation of the corresponding brain areas in REM sleep, which may exceed waking; at the same time, the cognitive deficits often thought to characterize dreams such as the loss of self-awareness, the absence of critical thinking, delusional reasoning, and mnemonic deficits fit in well with the comparative deactivation of frontal areas (Hobson et al. 2000). Hobson (1988, Hobson et al. 2000) has argued that the vivid, hallucinatory character of dreaming results from the fact that in REM sleep, the visual and motor areas are activated in the same way as in waking perception, the sole difference being dreams’ dependence on internal signal generation. Horikawa and colleagues (2013) used neuroimaging data from sleep onset to predict the types of objects described in mentation reports, which they took to support the perceptual equivalence between dreaming and waking.

Generally, versions of the hallucination view that suggest dreams replicate all aspects of waking perception are too vague to be informative. Especially for subtle perceptual activities (such as visual search), we might not know enough about dream phenomenology to make any strong claims (Nielsen 2010). Specifying points of similarity leads to a more informative and precise, but likely also more nuanced view. Dreams are heterogeneous, and some might be more perception-like while others resemble imagination (Windt 2015a). There might also be differences between or even within specific types of imagery. For example, visual imagery might be quite different from touch sensations, which tend to be rare in dreams (Hobson 1988). Visual dream imagery might overall resemble waking perception but lack color saturation, background detail and focus (Rechtschaffen & Buchignani, 1992). Classifying dreams as either hallucinatory or imaginative is further complicated by the fact that there is strong overlap in cortical activity associated with both visual imagery and perception (Zeidman & Maguire, 2016). This means even a strong overlap in cortical activity between, say, visual dream imagery and visual perception does not necessarily set dreaming apart from waking imagination.

This is also true for evidence on eye movements in dreams. LaBerge and colleagues (2018) recently showed that eye tracking of objects is smooth in lucid dreaming and perceiving, but not in imagining. Drawing from this evidence, Rosen (forthcoming) suggests many dreams mimic the phenomenology of interacting with a stable world, including eye movements and visual search. Others argue we should not analogize dream imagery to mind-independent, scannable objects and that eye movements might instead be implicated in the generation of dream imagery (Windt 2018).

Another way to make sense of the claim that dreaming has the same phenomenal character as waking perception is to say some kinds of dream imagery are illusory: they involve misperception of an external object as having different properties than it actually has (cf. Smith 2002; Crane & French 2017). The illusion view disagrees with the hallucination view on whether dreams have a contemporaneous external stimulus source.

The illusion view has fallen out of favor but has a long history. The Ancients believed dreams have bodily sources. This idea underlies the practice of using dreams to diagnose illness, as practiced in the shrines at Epidaurus (Galen On Diagnosis in Dreams ; van de Castle 1994). Aristotle ( On Dreams ) thought some dreams are caused by indigestion, and Hobbes adopted this view, claiming different kinds of dreams could be traced to different bodily sensations. For instance, “lying cold breedeth Dreams of Feare, and raiseth the thought and Image of some fearfull object” (Hobbes 1651: 91).

Appeals to the bodily sources of dreaming became especially popular in the 19 th and early 20 th centuries. Many believed specific dream themes such as flying were linked to sleeping position (Macnish 1838; Scherner 1861; Vold 1910/1912; Ellis 1911) and realizing, in sleep, that one’s feet are not touching the ground (Bergson 1914).

There were also attempts to explain the phenomenology of dreaming by appealing to the absence of outward movement. The lack of appropriate feedback and of movement and touch sensations was thought to cause dreams of being unable to move (Bradley 1894) or of trying but failing to do something (Gregory 1918).

Some proponents of the “ Leibreiztheorie ” (or somatic-stimulus theory) of dreaming attempted to go beyond anecdotal observations to conduct controlled experiments. Weygandt (1893) investigated the influence of various factors including breathing, blood circulation, temperature changes, urge to urinate, sleeping position, and visual or auditory stimulation during sleep on dream content (see Schredl 2010 for details). Singer (1924) proposed experiments on stimulus incorporation in dreams can inform claims on the ontology of dreaming: If dreams are sensations, a particular auditory stimulus should increase the frequency of dreams in nearby sleepers as well as the frequency of sound in their dreams, and it should decrease the range of quality and intensity of these dreams, making them overall more similar and predictable.

Newer studies provide evidence for the incorporation of external stimuli in dreams, including light flashes, sounds, sprays of water applied to the skin (Dement & Wolpert 1958), thermal (Baldridge 1966), electrical (Koulack 1969), and verbal stimuli (Berger 1963; Breger et al. 1971; Hoelscher et al., 1981), as well as blood pressure cuff stimulation on the leg (Nielsen et al. 1995; Sauvageau et al. 1998).

Muscular activity also often leaves its mark on dreams. It occurs throughout sleep but is especially frequent in REM sleep, mostly in the form of twitching but occasionally also in the form of larger, seemingly goal-directed movements (Blumberg 2010; Blumberg & Plumeau 2016). The relation between outward and dream movements is complex: in some cases, outward movements might mirror dream movements, while in others, sensory feedback might prompt dream imagery (Windt 2018).

Generally, it seems external and bodily stimuli can be related to varying degrees to dream and sleep onset imagery (Nielsen 2017; Windt 2018; Windt et al. 2016). Some of these cases appear to fit the concept of illusion, as in when the sound of the alarm clock is experienced, in a dream, as a siren, or when blood pressure cuff inflation on the leg leads to dreams of wearing strange shoes (Windt 2018; for these and other examples, see Nielsen et al. 1995). In other cases, such as when blood pressure cuff stimulation on the leg prompts a dream of seeing someone else’s leg being run over, describing this as illusory misperception might be less straightforward.

Saying that dreams can be prompted by external stimuli and that in some cases these are best described as illusions is different from the stronger claim, sometimes advanced by historical proponents of somatic-stimulus theory, that dreams generally are caused by external or bodily stimuli. As an example of the stronger claim, consider Wundt’s proposal that the

ideas which arise in dreams come, at least to a great extent, from sensations, especially from those of the general sense, and are therefore mostly illusions of fancy, probably only seldom pure memory ideas which hence become hallucinations. (Wundt 1896: 179)

This claim is likely too strong. It is also likely that appeals to external or bodily stimuli on their own cannot fully explain dream imagery, including when and how external stimuli are incorporated in dreams. Sensory incorporation in dreams is often hard to predict and indirect; associated imagery seems related not just to stimulus intensity, but also to short- and long term memories. A full explanation of dream content additionally has to take the cognitive and memory sources of dreaming into account (Windt 2018; Nielsen 2017; cf. Silberer 1919).

The most important rival to the hallucination view is that dreams are imaginative experiences (Liao & Gendler 2019; Thomas 2014). This can mean dream imagery involves imaginings rather than percepts (including hallucinations or illusions; McGinn 2004), that dream beliefs are imaginative and not real beliefs (Sosa 2007), or both (Ichikawa 2008, 2009). An important advantage is that by assimilating dreams to commonplace mental states such as waking fantasy and daydreaming, rather than a rare and often pathological occurrence such as hallucinations, it provides a more unified account of mental life (Stone 1984). However, the reasons for adopting the imagination view are diverse, and dreams have been proposed to resemble imaginings and differ from perception along a number of dimensions (e.g. McGinn 2004, 2005a,b; Thomas 2014). This issue is complicated by the fact that there is little agreement on the definition of imagination and its relation to perception (Kind 2013).

One way is to deny dreams involve presence or the feeling of being in a world, which many believe is central to waking perception. Imagination theorists compare the sense in which we feel present in our dreams to cognitive absorption, as when we are lost in a novel, film, or vivid daydream (Sartre 1940; McGinn 2004; but see Hering 1947; Globus 1987). Some argue that reflexive consciousness or meta-awareness (as in lucid dreams) interrupts cognitive absorption and terminates the ongoing dream (Sartre 1940), essentially denying lucid dreams are possible.

Another issue is whether dreams are subject to the will (Ichikawa 2009). Imagination is often characterized as active and under our control (Wittgenstein 1967: 621, 633), involving “a special effort of the mind” (Descartes 1641: VI, 2), whereas perception is passive. Because dreams just seem to happen to us without being under voluntary control, they present an important challenge for the imagination view. Ichikawa (2009) argues lucid control dreams show dreams are generally subject to the will even where they are not under deliberate control.

Dreams are widely described as more indeterminate than waking perception (James 1890: 47; Stone 1984). In scientific dream research, vagueness is regarded as one of three main subtypes of bizarreness (Hobson 1988; Revonsuo & Salmivalli 1995). An example are dream characters who are identified not by their behavior or looks, but by just knowing (Kahn et al. 2000, 2002; Revonsuo & Tarkko 2002). Dreams are also attention-dependent and lack foreground-background structure (Thompson 2014); while it is tempting to construe the dream world as rich in detail, there is no more to dreams than meets the eye, and many think dream experience is exhausted by what is the focus of selective attention (Hunter 1983; Thompson 2014).

Indeterminacy is also related to the question of whether we dream in color or in black and white. Based on a review of historical and recent studies, Schwitzgebel (2002, 2011) argues there has been a shift in theories on dream color that coincides with the rise first of black-and-white and then color television. He argues it is unlikely that dreams themselves changed from colored to black and white and back to colored, proposing that a change in opinion is a more plausible explanation. Maybe dreams were either black and white or colored all along; or maybe they are indeterminate with respect to color, as may be the case for imagined or fictional objects; were this the case, it would strengthen the imagination view (Ichikawa 2009). Schwitzgebel’s main point is that reports of colored dreaming are unreliable and our opinions about dreams can be mistaken (but see Windt 2013, 2015a). This relates to Schwitzgebel’s (2011; Hurlburt & Schwitzgebel 2007) general skepticism about the reliability of introspection.

The issue of dream color has led to a number of follow-up studies (Schwitzgebel 2003; Schwitzgebel et al. 2006; Murzyn 2008; Schredl et al. 2008; Hoss 2010). They suggest most people dream in color and a small percentage describe grayscale or even mixed dreams (Murzyn 2008) or dreams involving moderate color saturation (Rechtschaffen and Buchignani 1992). Indeterminacy is rarely reported.

The imagination view has consequences for Cartesian dream skepticism. If dream pain does not feel like real pain, there is a fail-safe way to determine whether one is now dreaming: one need only pinch oneself (Nelson 1966; Stone 1984; but see Hodges & Carter 1969; Kantor 1970). As Locke put it,

if our dreamer pleases to try, whether the glowing heat of a glass furnace, be barely a wandering imagination in a drowsy man’s fancy, by putting his hand into it, he may perhaps be wakened into a certainty greater than he could wish, that it is something more than bare imagination. (Locke 1689: IV.XI.8)

If dreaming feels different from waking, this raises the question why we tend to describe dreams in the same terms as waking perception. Maybe this is because most people haven’t thought about these matters and they would find the imagination view plausible if they considered it (Ichikawa 2009). Or maybe

it is just because we all know that dreams are throughout un like waking experiences that we can safely use ordinary expressions in the narration of them. (Austin 1962: 42)

Some authors classify dreams as imaginings while acknowledging they feel like perceiving. For example, Hobbes describes dreams as “the imaginations of them that sleep” (Hobbes 1651: 90), and imagination as a “ decaying sense ” (Hobbes 1651: 88). Yet he also uses the concepts of imagination and fancy to describe perception and argues “their appearance to us is Fancy, the same waking, that dreaming” (Hobbes 1651: 86).

In the scientific literature, the imagination view is complemented by cognitive theories. Foulkes (1978: 5) describes dreaming as a form of thinking with its own grammar and syntax, but allows that dream imagery is sufficently perception-like to deceive us. Domhoff’s neurocognitive model of dreaming (2001, 2003) emphasizes the dependence of dreaming on visuospatial skills and on a network including the association areas of the forebrain. The theory draws from findings on the partial or global cessation of dreaming following brain lesions (cf. Solms 1997, 2000), evidence that dreaming develops gradually and in tandem with visuospatial skills in children (Foulkes 1993a, 1999; but see Resnick et al. 1994), and results from dream content analysis supporting the continuity of dreaming with waking concerns and memories (the so-called continuity hypothesis ; see Domhoff 2001, 2003; Schredl & Hofmann 2003; Schredl 2006; see also Nir & Tononi 2010).

A number of researchers have begun to consider dreaming in the context of theories of mind wandering. Mind wandering is frequent in waking and involves spontaneous thoughts that unfold dynamically and are only weakly constrained by ongoing tasks and environmental demands (Schooler et al. 2011; Smallwood & Schooler 2015; Christoff et al. 2016). Based on phenomenological and neurophysiological similarities, dreams have been proposed to be an intensified form of waking mind wandering (Pace-Schott 2007, 2013; Domhoff 2011; Wamsley 2013; Fox et al. 2013). This basic idea seems to have been anticipated by Leibniz, who noted that the spontaneous formation of visions in dreams surpasses the capacity of our waking imagination (Leibniz, Philosophical Papers and Letters , Vol. I, 177–178).

The analogy between dreams and waking mind wandering has been discussed in the context of cognitive agency. Metzinger (2013a,b, 2015) describes dreams and waking mind wandering as involving a cyclically recurring loss of mental autonomy, or the ability to deliberately control one’s conscious thought processes. Dreams and waking mind wandering are not mental actions but unintentional mental behaviors, comparable to subpersonal processes such as breathing or heartbeat. Because dreaming and waking mind wandering make up a the majority of our conscious mental lives, he argues that cognitive agency and mental autonomy are the exception, not the rule.

This raises the question of how to make sense of lucid control dreams, which involve both meta-awareness and agency. Windt and Voss (2018) argue that in such cases, spontaneous processes including imagery formation co-exist alongside more deliberate, top-down control; they also argue metacognitive insight and control themselves can have spontaneous elements. This suggests spontaneity and control are not opposites, but a more complex account is needed. Possibly, certain dreams and instances of waking mind wandering can be both spontaneous and agentive.

The analogy with mind wandering might help move forward the debate on the ontology of dreaming. In this debate, a common assumption is that dreams can be categorized as either hallucinatory or imaginative. Yet the application of these terms to dreams quickly runs into counterexamples and it is unclear they are mutually exclusive. One option is pluralism (Rosen 2018b), in which some aspects of dreaming are hallucinatory, others imaginative, and yet again others illusory. Another is that dreams are sui generis, combining aspects associated with wake states such as hallucinating, imagining, or perceiving in a novel manner without mimicking them completely. Windt (2015a) proposes that mind wandering, which describes a range of mental states loosely characterized by their spontaneous and dynamic character, might be particularly suitable for the characterization of dreaming precisely because that term leaves open more specific questions on the phenomenology of dreaming, allowing for variation in control, determinacy, and so on. This might be a good starting point for describing what is unique about dreaming while also acknowledging continuities across sleep-wake states and capitalizing on the strengths of the hallucination, illusion, imagination, and cognitive views.

The second strand of the imagination view argues that dream beliefs are not real beliefs, but propositional imaginings. This may or may not be combined with the claim that dream imagery is imaginative rather than perceptual (Sosa 2007; Ichikawa 2009).

Denying that dream beliefs have the status of real beliefs only makes sense before the background of a specific account of what beliefs are and how they are distinguished from other mental states such as delusions or propositional imaginings. For instance, Ichikawa (2009) argues that if we follow interpretationist or dispositionalist accounts of belief, dream beliefs fall short of real beliefs. He claims dream beliefs lack connection with perceptual experience and fail to motivate actions; consequently, they do not have the same functional role as real beliefs. Moreover, we cannot ascribe dream beliefs to a person by observing them lying asleep in bed. Dream beliefs are often inconsistent with longstanding waking beliefs and acquired and discarded without any process of belief revision (Ichikawa 2009).

This analysis of dream beliefs has consequences for skepticism. If dream beliefs are propositional imaginings, then we do not falsely believe while dreaming that we are now awake, but only imagine that we do (Sosa 2007). It is not clear though that this protects us from deception. If dream beliefs fall short of real beliefs, this might even make the specter of dream deception more worrisome: in mistaking dream beliefs for the real thing, we would now be deceived about the status of our own mental states (Ichikawa 2008).

It is also not clear whether the same type of argument extends to mental states other than beliefs. As Lewis points out, a person might

in fact believe or realize in the course of a dream that he was dreaming, and even if we said that, in such case, he only dreamt that he was dreaming, this still leaves it possible for someone who is asleep to entertain at the time the thought that he is asleep. (Lewis 1969: 133)

Mental states other than believing such as entertaining, thinking, or minimally appraisive instances of taking for granted might be sufficient for deception (Reed 1979).

The debate about dream beliefs is paralleled by a debate about whether delusions are beliefs or imaginings (see Currie 2000; Currie & Ravenscroft 2002; McGinn 2004; Bayne & Pacherie 2005; Bortolotti 2009; Gendler 2013). Both debates might plausibly inform each other, especially as dreams are sometimes proposed to be delusional (Hobson 1999).

3. Dreaming and theories of consciousness

Dreams are a global state of consciousness in which experience arises under altered behavioral and neurophysiological conditions as compared to standard wakefulness; unlike other altered states of consciousness (such as drug-induced or deep meditative states) and pathological wake states (such as psychosis or neurological syndromes), dreams occur spontaneously and regularly in healthy subjects. For both reasons, many regard dreams as a test case for theories of consciousness or even an ideal model system for consciousness research (Churchland 1988; Revonsuo 2006).

Existing proposals differ on the phenomenology of dreaming: referring to dream bizarreness, Churchland describes dream experience as robustly different from waking, whereas Revonsuo argues dreaming is similar to waking and the purest form of experience:

the dreaming brain brings out the phenomenal level of organization in a clear and distinct form. Dreaming is phenomenality pure and simple, untouched by external physical stimulation or behavioural activity. (Revonsuo 2006: 75)

Revonsuo argues dreaming reveals the basic, state-independent structure of consciousness to be immersive: “dreaming depicts consciousness first and foremost as a subjective world- for-me ” (Revonsuo 2006: 75). This leads him to introduce the “world-simulation metaphor of consciousness”, according to which consciousness itself is essentially simulational and dreamlike. This is taken to support internalism about conscious experience.

This latter claim is also contentious. Noë (2004: 213) argues that phenomenological differences between dreaming and waking (such as greater instability of visual dream imagery) result from the lack of dynamic interaction with the environment in dreams. He proposes this shows that neural states are sufficient for dreaming but denies they are also sufficient for perceptual experience.

A possible problem for both views is their reliance on background assumptions about the phenomenology of dreaming and its disconnection from environmental stimuli and bodily sensations. Windt (2015a, 2018) argues both internalism and externalism mistakenly assume dreams to be isolated from external sensory input and own-body perception; she believes both the phenomenology of dreaming and its correlation with external stimuli are complex and variable. She argues the analysis of dreaming does not clearly support either side in the debate on internalism vs externalism (but see Rosen 2018a). Generally, in the absence of a well worked out theory of dreaming and its sleep-stage and neural correlates, proposals for using dreaming as a model system or test case run the risk of relying on an oversimplified description of the target phenomenon (Windt & Noreika 2011).

Recent accounts appealing to generative models and predictive processing (Clark 2013b; Hohwy 2013) suggest a new, unified account of perception, imagination, and dreaming. In these accounts, different mental states, including perception and action, embody different strategies of hypothesis testing and prediction error minimization. Perception is the attempt to model the hidden external causes of sensory stimuli; action involves keeping the internal model stable while changing the sensory input. Clark argues that on such a model,

systems that know how to perceive an object as a cat are thus systems that, ipso facto , are able to use a top-down cascade to bring about the kinds of activity pattern that would be characteristic of the presence of a cat. […] Perceivers like us, if this is correct, are inevitably potential dreamers and imaginers too. Moreover, they are beings who, in dreaming and imagining, are deploying many of the very same strategies and resources used in ordinary perception. (Clark 2013a: 764)

Predictive processing accounts have also been used to explain specific features of dreaming. Bizarreness has been associated with the comparative lack of external stimulus processing, implying dream imagery is relatively unconstrained by prediction errors (cf. Hobson & Friston 2012; Fletcher & Frith 2008; Bucci & Grasso 2017). Windt (2018) suggests a predictive processing account of dream imagery generation that links bodily self-experience to own-body perception and subtle motor behaviors such as twitching in REM sleep (Blumberg 2010; Blumberg & Plumeau 2016). She argues that movement sensations in dreams, in relation to REM-sleep related muscle twitching, involve a form of bodily self-sampling in which coordinated muscular activity contributes to the generation and maintenance of a body model. This is important because in predictive processing accounts neither the bodily nor the external causes of sensory inputs are known; at the same time, having an accurate body model is a prerequisite for action, requiring the system to disambiguate between self- and other generated changes to sensory inputs. Especially in early development, sleep might provide the ideal conditions for exploring one’s own body via subtle but coordinated muscular activity while processing of visual and auditory stimuli is reduced.

Dreams have also been suggested as a test case for whether phenomenal consciousness can be divorced from cognitive access (e.g., Block 2007; but see Cohen & Dennett 2011). Sebastián (2014a) argues that dreams provide empirical evidence that conscious experience can occur independently of cognitive access. This is because during (non-lucid) REM-sleep dreams, the dorsolateral prefrontal cortex (dlPFC) as the most plausible mechanism underlying cognitive access is selectively deactivated (see also Pantani et al. 2018). This would challenge theories linking conscious experience to access, such as higher-order-thought theory (Sebastián 2014b). However, both the hypoactivation of the dlPCF in REM sleep and its association with cognitive access have been debated. Fazekas and Nemeth (2018) suggest that certain kinds of cognitive access may be independent of dlPFC activation, necessitating a more complex account.

Dreaming has been suggested as a model system not just of waking consciousness in general, but also of psychotic wake states in particular. The analogy between dreaming and madness has a long philosophical history (Plato, Phaedrus ; Kant 1766; Schopenhauer 1847) and finds particularly stark expression in Hobson’s claim that “dreaming is not a model of a psychosis. It is a psychosis. It’s just a healthy one” (Hobson 1999: 44). Gottesmann (2006) proposes dreaming as a neurophysiological model of schizophrenia. There is a rich discussion on the theoretical and methodological implications of dream research for psychiatry (see Scarone et al. 2007; d’Agostino et al. 2013; see Windt & Noreika 2011 as well as the other papers in this special issue) and a number of studies have investigated differences in dream reports from schizophrenic and healthy subjects (Limosani et al. 2011a,b).

Rather than likening dreaming to waking in general or specific wake states such as psychosis, there have also been attempts to compare specific dream phenomena to wake-state delusions. Gerrans (2012, 2013, 2014) focuses on character misidentification in dreams and delusions of hyperfamiliarity (such as the Frégoli delusion, in which strangers are mistakenly identified as family members, and déjà vu ) to argue that anomalous experience and faulty reality testing both play a role in delusion formation. Rosen (2015) analyzes instances of thought insertion and of auditory hallucinations, which are key symptoms of schizophrenia, to raise broader questions about the altered sense of agency in dreams as compared to waking.

Philosophers have focused almost exclusively on dreaming, largely leaving to the side questions about dreamless sleep including whether it is uniformly unconscious. In recent years there has been a surge of interest in the possibility of dreamless sleep experience and foundational issues about the definition of sleep and waking. This has been paralleled by growing interest in dreaming in NREM sleep.

Conceptually, interest in dreamless sleep experience has been facilitated by the precise definition of dreaming offered by simulation views (Revonsuo et al. 2015). If dreams are immersive sleep experiences characterized by their here -and- now structure, it makes sense to ask whether this is true for all or just a subset of sleep-related experiences and whether non-immersive sleep experiences exist. By contrast, if dreaming is broadly identified with any conscious mentation in sleep (Pagel et al. 2001), there is no conceptual space for dreamless sleep experience.

Following Thompson's (2014, 2015) discussion of dreamless sleep in Indian and Buddhist philosophy, Windt and colleagues (2016; see also Windt 2015b) introduce a framework for different kinds of dreamless sleep experience ranging from thinking and isolated imagery, perception, or bodily sensations, where these lack integration into a scene, to minimal kinds of experience lacking imagery or specific thought contents. A possible example of minimal phenomenal experience in sleep are white dreams, where people report having had experiences during sleep but cannot remember any details. Taken at face value, some white dream reports might describe experiences that lack reportable content (Windt 2015b); others might describe forgotten dreams or dreams with degraded content (Fazekas et al. 2018). Another example are reports of witnessing dreamless sleep, as described in certain meditation practices. This state is said to involve non-conceptual awareness of sleep, again in the absence of imagery or specific thought contents, and loss of sense of self (Thompson 2014, 2015). Some schools in Buddhist philosophy explain claims of deep and dreamless sleep by saying we never fully lose consciousness in sleep (Prasad 2000, 66; and Thompson 2014, 2015).

Empirically, interest in dreamless sleep experience is paralleled by increasing interest in experiences in NREM sleep (Fazekas et al. 2018). Most researchers now accept that dreaming is not confined to REM sleep, but also occurs at sleep onset and in NREM sleep. The deeper stages of NREM sleep are particularly interesting as they involve roughly similar proportions of dreaming, unconscious sleep, and white dreams (Noreika et al. 2009: Siclari et al. 2013, 2017). In the search for the neural correlates of dreaming vs unconscious dreamless sleep, this makes comparisons within the same sleep stage possible and avoids confounds involved in comparing presumably dreamful REM sleep with presumably dreamless NREM sleep. Findings suggest that activity in the same parietal hot zone underlies dreaming in both NREM and REM sleep (Siclari et al. 2017).

Where sleep and dream research have traditionally tried to identify the sleep stage correlates of dreaming, newer research suggests local changes occurring independently of sleep stages might in fact be more relevant. Traditionally regarded as global, whole-brain phenomena, there is now increasing evidence that sleep itself is locally driven, and local changes in sleep depth might be associated with changes in sleep-related experience (Siclari & Tononi 2017; Andrillon et al. 2019). While sleep and dream research are often considered as separate fields, changes in how sleep in general and sleep stages in particular are defined appear closely associated with changes in the theoretical conception of dreaming and its empirical investigation.

Historically, discoveries about dreaming have precipitated changing conceptions of sleep (for an excellent history of the study of sleep and dreaming, see Kroker 2007). Following Aristotle ( On Sleeping and Waking ), sleep was traditionally defined in negative terms as the absence of wakefulness and perception. This is still reflected in Malcolm’s assumption that “to a person who is sound asleep, ‘dead to the world’, things cannot even seem” (Malcolm 1956: 26). With the discovery of REM sleep, sleep came to be regarded as a heterogeneous phenomenon characterized by the cyclic alteration of different sleep stages. REM sleep was now considered as “neither sleeping nor waking. It was obviously a third state of the brain, as different from sleep as sleep is from wakefulness” (Jouvet 1999: 5). The folk-psychological dichotomy between sleep and wakefulness now seemed oversimplified and empirically implausible. At the same time dreaming, which had previously been considered as an intermediate state of half-sleeping and half-waking, came to be regarded as a genuine sleep phenomenon, but narrowed to REM sleep. Today, the framework for describing dreams and other sleep-related experiences is more precise, but dreaming has also been cast adrift from REM sleep.

A closely associated issue is how to define waking. Crowther’s (2018) capacitation thesis casts waking consciousness as a state in which the individual is fully switched on to their environment, but also to their own epistemic (cf. O’Shaugnessy 2002) and agentive potential; the waking individual is empowered to act and think in certain ways, though this potential need not be actualized. By contrast, dreaming is an “imagining-of consciousness” (O’Shaughnessy 2002: 430) and consciousness is conceptually tied to wakefulness. Because in lucid dreams, the epistemic and agentive profile of waking is at least partly realized, they might, according to Crowther, be regarded as closer to waking than nonlucid dreams.

This account of waking and sleep may also have consequences for the imagination model of dreaming and dream skepticism (Soteriou 2017). As in the imagination model, dreaming would be passive and action, including cognitive agency, would be tied to waking. If dreaming nonetheless involved passive episodes of imagining oneself to be active, one would be unable to tell that one were dreaming and imagining, as this insight would require the exercise of real agency. The sceptical consequence would be that when dreaming, one would lose agency as well as the capacity to gain insight into one’s current state. Yet our ability to know we are waking when waking would be unscathed; according to Soteriou, waking would thus have an epistemic function connected to the capacity to exercise agency over our mental lives.

Finally, definitions of consciousness themselves are bound up with conceptions of sleep and dreaming. As dreaming went from a state whose experiential status was doubted to being widely recognized as a second global state of consciousness, consciousness sometimes came to be defined contrastively as that which disappears in deep, dreamless sleep and reappears in waking and dreaming (Searle 2000; Tononi 2008). In light of dreamless sleep experience, such definitions are problematic (Thompson 2014, 2015; Windt 2015b; Windt et al. 2016). Dreamless sleep experience has been proposed to be particularly relevant for understanding minimal phenomenal experience, or the conditions under which the simplest kind of conscious experience arises (Windt 2015b). The investigation of dreamless sleep might thus shed light on the transition from unconscious sleep to sleep-related experience.

We almost always have a self in dreams, though this self can sometimes be a slightly different (e.g. older or younger) version of our waking self or even a different person entirely. Dreams therefore raise interesting questions about the identity between the dream and waking self. Locke (1689) invites us to imagine two men alternating in turns between sleep and wakefulness and sharing one continuously thinking soul (Locke 1689: II.I.12). He argues that if one man retained no memory of the soul’s thoughts and perceptions while it was linked to the other man’s body, they would be distinct persons. His position is that personal identity depends on psychological continuity, including recall: in the absence of recall, as illustrated by the toy example of two people sharing one soul, continuous conscious thinking does not suffice for identity. Locke also rejects the possibility of unrecalled dreams and the idea that we dream throughout sleep, remembering only a small proportion of our dreams (Locke 1689: II.I.19).

Valberg distinguishes between the subject of the dream (i.e., the dream self) and the sleeping person who is the dreamer of the dream and recalls it upon awakening (Valberg 2007). He argues that awakening from a dream involves crossing a chasm between discrete worlds with discrete spaces and times; it does not make sense to say that “the ‘I’ at these times [is] a single individual who crosses from one world to the other” (Valberg 2007: 69). According to Valberg, this is relevant to dream skepticism because there is no simple way to make sense of the claims that it is I who emerge from a dream or that I was the victim of dream deception.

Vicarious dreams, or dreams in which the protagonist of the dream seems to be a different person from the dreamer, are particularly puzzling with respect to identity. They may even raise the question of whether the dream self has an independent existence (Rosen & Sutton 2013: 1047). Such dreams are superficially similar to cases in which we imagine being another person, but according to Rosen and Sutton require a different explanation: in the case of dreaming, the imagined person’s thoughts are not framed as diverging from one’s own and one does not retain one’s own perspective in addition to the imagined one; in nonlucid dreams, only the perspective of the dream’s protagonist is retained.

The dream self is also at the center of simulation views of dreaming, which define dreaming via its immersive, here and now character as the experience of a self in a world. This leads to further questions about the phenomenology of self-experience in dreams and how it is different from waking self-experience. Different versions of the simulation view focus on different aspects of self- and world experience in dreams, ranging from social simulation (Revonsuo et al. 2015) to the typical features of selfhood in dreams (Revonsuo 2005, 2006, Metzinger 2003, 2009) to the minimal conditions for experiencing oneself as a self in dreams and what this tells us about minimal phenomenal selfhood in general (Windt 2015a, 2018). Yet these different versions of the simulation view are largely complementary and together have forged unity in a field that was previously hampered by lack of agreement about the definition of dreaming. They also integrate the philosophy of dreaming and scientific dream research.

As so often in debates about dreaming, there is disagreement about basic phenomenological questions. Revonsuo (2005) describes self-experience including bodily experience in dreams as identical to waking, whereas Metzinger (2003, 2009; see also Windt & Metzinger 2007) argues that important layers of waking self-experience (such as autobiographical memory, agency, a stable first-person perspective, metacognitive insight, and self-knowledge) are missing in nonlucid dreams. He argues this is due to the cognitive and mnemonic deficit that characterizes nonlucid dreams (cf. Hobson et al. 2000). Windt (2015a) analyzes the range of cognitive and bodily self-experience in dreams, both of which she describes as variable. She argues that in a majority of cases, dreams are weakly phenomenally embodied states in which bodily experience is largely related to movement sensations but a detailed and integrated body representation is lacking; instead, bodily experience in dreams is largely indeterminate (for an attempt to test this empirically, see Koppehele-Gossel et al. 2016). She proposes this is because dreams are also weakly functionally embodied states, in which the specific pattern of bodily experience reflects altered processing of bodily sensations (as in the illusion view). She also analyzes instances of bodiless dreams, in which dreamers say they experienced themselves as disembodied entities, to argue that self-experience can be reduced to pure spatiotemporal-self-location (Windt 2010); she proposes these cases can help identify the conditions for the emergence of minimal phenomenal selfhood (Blanke & Metzinger 2009; see also Metzinger 2013b).

How the phenomenology of dreaming compares to waking and what to say about how the dream self relates to the waking self bears on questions about the moral status of dreams. For Augustine ( Confessions ) dreams were a cause of moral concern because of their indistinguishability from waking life. What particularly worried him about dreams of sexual acts was their vividness, as well as the feeling of pleasure and seeming acquiescence or consent on the part of the dreamer. He concluded, however, that the transition from sleep to wakefulness involves a radical chasm, enabling the dreamer to awaken with a clear conscience and absolving them from taking responsibility for their dream actions.

What exactly Augustine thought the chasm between dreaming and waking consists in allows for different interpretations (Matthews 1981). Firstly, if the dream and waking self are not identical, then waking Augustine is not morally responsible for dream-Augustine’s actions. Secondly, actions performed in dreams might be morally irrelevant because they did not really happen. And thirdly, assuming that moral responsibility requires the ability to act otherwise, dreams provide no grounds for moral concern because we cannot refrain from having certain types of dreams.

The issue of dream immorality may also present a choice point between different accounts of moral evaluation. Where internalists assume the moral status of a person’s actions is entirely determined by internal factors such as intentions and motives, externalists look beyond these to the effects of actions. Driver (2007) argues that the absurdity of dream immorality itself should count against purely internalist accounts; yet she also acknowledges this absurdity is not a necessary feature of dreams.

Central to the question of dream immorality is the status of dreams as actions rather than mere behaviors. Mullane (1965) argues that while we don’t have full control over our dreams, they are not completely involuntary either; as is the case for blushing, considerable effort is required to attain control over our dreams and in some cases they can even be considered as actions. That lucid dream control is, to some extent, a learnable skill (Stumbrys et al. 2014) lends some support to this claim.

6. The meaning of dreams and the functions of dreaming

Philosophical discussions of dreaming tend to focus on (a) dream deception and (b) questions about the ontology of dreaming, its moral status, etc., that tend to intersect with dream skepticism. By contrast, the main source of interest in dreams outside of philosophy traditionally has been dream interpretation and whether dreams are a source of knowledge and insight. Historically, the epistemic status of dreams and the use of prophetic and diagnostic dreams was not just a theoretical, but a practical problem (Barbera 2008). Different types of dreams were distinguished by their putative epistemic value. Artemidorus, for instance, used the term enhypnion to refer to dreams that merely reflect the sleeper’s current bodily or psychological state and hence do not merit further interpretation, whereas he reserved the term oneiron for meaningful and symbolic dreams of divine origin.

The practice of dream interpretation was famously attacked by Aristotle in On Prophecy in Sleep . He denied that dreams are of divine origin, but allowed that occasionally, small affections of the sensory organs as might stem from distant events that cannot be perceived in waking are perceptible in the quiet of sleep. He also believed such dreams were mostly likely to occur in dullards whose minds resemble an empty desert – an assessment that was not apt to encourage interest in dreams (Kroker 2007: 37). A similarly negative view was held by early modern philosophers who believed dreams were often the source of superstitious beliefs (Hobbes 1651; Kant 1766; Schopenhauer 1847).

In Freudian dream theory, dream interpretation once more assumed a prominent role as the royal road to knowledge of the unconscious. This was associated with claims about the psychic sources of dreaming. Freud (1899) also rejected the influence of external or bodily sources, as championed by contemporary proponents of somatic-stimulus theory.

In the neuroscience of dreaming, Hobson famously argued that dreams are the product of the random, brain-stem driven activation of the brain during sleep (Hobson 1988) and at best enable personal insights in the same way as a Rorschach test (Hobson et al. 2000). Dennett (1991) illustrates the lack of design underlying the production of dream narratives through the “party game of psychoanalysis”, which involves an aimless game of question-and-answer. In the game, players follow simple rules to jointly produce narratives that can seem symbolic and meaningful, even though no intelligent and deliberate process of narration was involved.

Even if we grant that dreams are not messages from a hidden entity in need of decoding, this does not imply that dream interpretation cannot be a personally meaningful source of insight and creativity (Hobson & Wohl 2005). Whether and under which conditions, and following which methods, dream interpretation can lead to personally significant insights is an empirical question that is only beginning to be investigated systematically (see Edwards et al. 2013).

Finally, throughout history, views on the epistemic status of dreams and the type of knowledge to be gained from dream interpretation (e.g., knowledge about the future, diagnosis of physical illness, or insights about one’s current concerns) often changed in tandem with views on the origin and sources of dreaming, which gradually moved from divine origins and external sources, via the body, to the unconscious, and finally to the brain.

Different theories on the functions of dreaming have been proposed and the debate is ongoing. An important distinction is between the functions of sleep stages and the functions of dreaming. Well-documented functions of REM sleep include thermoregulation and the development of cortical structures in birds and mammals, as well as neurotransmitter repletion, the reconstruction and maintenance of little-used brain circuits, the structural development of the brain in early developmental phases, as well as the preparation of a repertoire of reflexive or instinctive behaviors (Hobson 2009). Yet none of these functions are obviously linked to dreaming. An exception is protoconsciousness theory, in which REM sleep plays an important role in foetal development by providing a virtual world model even before the emergence of full-blown consciousness (Hobson 2009: 808) .

Numerous studies have investigated the contribution of sleep to memory consolidation, with different sleep stages promoting different types of memories (Diekelmann et al. 2009; Walker 2009). However, only a few studies have investigated the relationship between dream content and memory consolidation in sleep (for a review, see Nielsen & Stenstrom 2005). Dreams rarely involve episodic replay of waking memories (Fosse et al. 2003). The incorporation of memory sources seems to follow a specific temporal pattern in which recent memories are integrated with older but semantically related memories (Blagrove et al. 2011). Nielsen (2017) presents a model of how external and bodily stimuli on one hand and short- and long-term memories on the other hand form seemingly novel, complex, and dreamlike images at sleep onset; he proposes these microdreams shed light on the formation and sources of more complex dreams. There is also some evidence that dream imagery might be associated with memory consolidation and task performance after sleep, though this is preliminary (Wamsley & Stickgold 2009, 2010; Wamsley et al. 2010).

Prominent theories on the function of dreaming focus on bad dreams and nightmares. It has long been thought that dreaming contributes to emotional processing and that this is particularly obvious in the dreams of nightmare sufferers or in dreams following traumatic experiences (e.g., Hartmann 1998; Nielsen & Lara-Carrasco 2007; Levin & Nielsen 2009; Cartwright 2010; Perogamvros et al. 2013). Based on the high prevalence of negative emotions and threatening dream content, threat simulation theory suggests that the evolutionary function of dreaming lies in the simulation of ancestral threats and the rehearsal of threatening events and avoidance skills in dreams has an adaptive value by enhancing the individual’s chances of survival (see Revonsuo 2000; Valli 2008). A more recent proposal is social simulation theory, in which social imagery in dreams supports social cognition, bonds, and social skills. (Revonsuo et al. 2015).

An evolutionary perspective can also be fruitfully applied to specific aspects of dream phenomenology. According to the vigilance hypothesis , natural selection disfavored the occurrence of those types of sensations during sleep that would compromise vigilance (Symons 1993). Dream sounds, but also smells or pains might distract attention from the potentially dangerous surroundings of the sleeping subject, and the vigilance hypothesis predicts that they only rarely occur in dreams without causing awakening. By contrast, because most mammals sleep with their eyes closed and in an immobile position, vivid visual and movement hallucinations during sleep would not comprise vigilance and thus can occur in dreams without endangering the sleeping subject. Focusing on the stuff dreams are not made of might then be at least as important for understanding the function of dreaming as developing a positive account.

Finally, even if dreaming in general and specific types of dream content in particular were found to be strongly associated with specific cognitive functions, it would still be possible that dreams are mere epiphenomena of brain activity during sleep (Flanagan 1995, 2000). It is also possible that the function of dreams is not knowable (Springett 2019).

A particular problem for any theory on the function of dreaming is to explain why a majority of dreams are forgotten and how dreams can fulfill their putative function independently of recall. Crick and Mitchinson (1983) famously proposed that REM sleep “erases” or deletes surplus information and unnecessary memories, which would suggest that enhanced dream recall is counterproductive. Another problem is that dreaming can be lost selectively and independently of other cognitive deficits (Solms 1997, 2000).

Some of the problems that arise for theories on the functions of dreaming can be avoided if we do not assume that dreaming has a specific function, separate from the function(s) of conscious wakeful states. This depends on the broader taxonomy of dreaming in relation to wakeful states. For example, if dreaming is continuous with waking mind wandering, imagination, and/or own-body perception, we should not expect it to have a unique function, but rather to express a similar function as these wakeful states, perhaps to varying degrees. Nor should we expect dreams to have a single function; the functions of dreaming might be as varied and complex as those of consciousness, and given the complexity of the target phenomenon, the failure to pin down a single function should not be surprising (Windt 2015a).

Questions about dreaming in different areas of philosophy such as epistemology, ontology, philosophy of mind and cognitive science, and ethics are closely intertwined. Scientific evidence from sleep and dream research can meaningfully inform the philosophical discussion and has often done so in the past. The discussion of dreaming has also often functioned as a lens on broader questions about knowledge, morality, consciousness, and self. Long a marginalized area, the philosophy of dreaming and of sleep is central to important philosophical questions and increasingly plays an important role in interdisciplinary consciousness research, for example in the search for the neural correlates of conscious states, in conscious state taxonomies, and in research on the minimal conditions for phenomenal selfhood and conscious experience.

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How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

• Philosophy of Dreaming , entry in the Internet Encyclopedia of Philosophy .
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• Dreams and Skepticism , PhilPapers collection.

belief | Berkeley, George | delusion | Descartes, René: epistemology | imagination | Locke, John | perception: the problem of | personal identity | personal identity: and ethics | Plato: on knowledge in the Theaetetus | sense data | skepticism | skepticism: and content externalism

Acknowledgments

I want to thank Regina Fabry and two anonymous reviewers for helpful comments and constructive criticism on an earlier version of this manuscript. And as always, I am greatly indebted to Stefan Pitz for his support.

Copyright © 2019 by Jennifer M. Windt < jennifer . windt @ monash . edu >

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December 12, 2023

Why Do We Dream? Maybe to Ensure We Can Literally ‘See’ the World upon Awakening

A theory holds that dreams are a way for the visual cortex of the brain to “defend its turf” against being “taken over” to process inputs from other senses

By Roberta McLain

Visual pathway and cortex.

janulla/Getty Images

Dreams have fascinated people for millennia, yet we struggle to understand their purpose. Some theories suggest dreams help us deal with emotions, solve problems or manage hidden desires. Others postulate that they clean up brain waste, make memories stronger or deduce the meaning of random brain activity. A more recent theory suggests nighttime dreams protect visual areas of the brain from being co-opted during sleep by other sensory functions, such as hearing or touch.

David Eagleman, a neuroscientist at Stanford University, has proposed the idea that dreaming is necessary to safeguard the visual cortex—the part of the brain responsible for processing vision. Eagleman’s theory takes into account that the human brain is highly adaptive, with certain areas able to take on new tasks, an ability called neuroplasticity. He argues that neurons compete for survival. The brain, Eagleman explains, distributes its resources by “implementing a do-or-die competition” for brain territory in which sensory areas “gain or lose neural territory when inputs slow, stop or shift.” Experiences over a lifetime reshape the map of the brain. “Just like neighboring nations, neurons stake out their territory and chronically defend them,” he says.

Eagleman points to children who have had half their brain removed because of severe health problems and then regain normal function. The remaining brain reorganizes itself and takes over the roles of the missing sections. Similarly, people who lose sight or hearing show heightened sensitivity in the remaining senses because the region of the brain normally used by the lost sense is taken over by other senses.

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Reorganization can happen fast. Studies published in 2007 and 2008 by Lotfi Merabet of Harvard Medical School and his colleagues showed just how quickly this takeover can happen. The 2008 study, in which subjects were blindfolded, revealed that the seizing of an idle area by other senses begins in as little as 90 minutes. And other studies found that this can occur within 45 minutes.

When we sleep, we can smell, hear and feel, but visual information is absent—except during REM sleep. About 90 minutes after drifting off to sleep, you enter REM. It begins when neurons in your brain stem, the stalklike section at the bottom of the organ, signal the beginning of two important tasks. Activity of these neurons, for one, paralyze major muscles, preventing the sleeper from acting out what is happening in the dream. Also, these brain cells send messages directly to the visual cortex, which initiates the dreaming process.

Why does REM follow that timetable? It conforms to when the visual cortex needs to start defending its territory, Eagleman argues. Scans of dreaming people show most of the brain activity associated with REM is within the visual cortex. Dreams are the brain’s way of fighting takeover from other senses, according to Eagleman, and REM activation prompts internally generated activity in the visual cortex as a means to safeguard its territory. As long as the neurons in the visual cortex are actively performing their customary job—in this case, generating visual imagery—they will not be commandeered by nearby neurons that process other sensory information.

Eagleman argues that the more plastic the brain, the more REM sleep is necessary to mount a defense. For babies to develop properly, they must sleep a lot, spending almost 50 percent of their time in REM sleep. But as people age, their brain becomes less flexible. (Think of how easily children learn languages, compared with adults.) At the same time, adults spend less time in REM sleep.

The correlation between adaptability and REM seems to hold across species. According to Eagleman, “Mother Nature drops human brains into the world half-baked and lets experience take over and shape them.” He argues the less hardwired a species’ brain is at birth, the more ability it has to adapt and learn from experience. But this has its disadvantages. For example, fawns and calves are able to walk within hours of birth because the behavior is hardwired. Human babies, with their more adaptable brains, require significantly more REM sleep than animals born with more hardwired brains.

Some researchers—in particular, dream researchers—disagree with Eagleman’s hypothesis. One example that raises doubts is the fact that the blind mole rat does not see and still experiences REM sleep. Yet some evolutionary adaptations are vestigial remnants of traits that were useful in the past but have become less significant as animals have evolved. So perhaps there was no pressure for blind mole rats to lose REM activity as they evolved without vision.

Antonio Zadra, a dream researcher at the University of Montreal, claims Eagleman’s theory “has little to do with actual dreaming and explains almost nothing about dreams per se, as opposed to REM sleep.” He asserts the theory “is, for me and many others who actually work in the field, silly and overly reductionistic and simplistic.”

Deirdre Leigh Barrett, a psychologist at Harvard University, former president of the International Association for the Study of Dreams and author of The Committee of Sleep , however, is more willing to consider Eagleman’s hypothesis. “It’s very convincing that there's a correlation between smarter animals and more elaborate brains,” she says. As far as dreams defending brain real estate, “I have a little more trouble with the visual argument, but it’s interesting.”

Eagleman says that his theory can accommodate other explanations for dreams and that REM sleep may serve many purposes besides protecting the visual cortex. Think of dreaming like a computer screen saver that is set to go off every 90 minutes—except that instead of protecting against frozen images, dreams prevent the visual cortex from being usurped by other functions. These visual hallucinations in the night may let us see during the day.

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Why Do We Dream?

There's no single consensus about which dream theory best explains why we dream

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Dr. Sabrina Romanoff, PsyD, is a licensed clinical psychologist and a professor at Yeshiva University’s clinical psychology doctoral program.

Verywell / Madelyn Goodnight

What Is a Dream Theory?

• The Role of Dreams
• Reflect the Unconscious
• Process Information
• Aid In Memory
• Spur Creativity
• Reflect Your Life
• Prepare and Protect
• Process Emotions
• Other Theories

Lucid Dreaming

Stress dreams.

A dream theory is a proposed explanation for why people dream that is backed by scientific evidence. Despite scientific inquiry, we still don't have a solid answer for why people dream. Some of the most notable theories are that dreaming helps us process memories and better understand our emotions , also providing a way to express what we want or to practice facing our challenges.

At a Glance

There is no single dream theory that fully explains all of the aspects of why we dream. The most prominent theory is that dreams help us to process and consolidate information from the previous day. However, other theories have suggested that dreams are critical for emotional processing, creativity, and self-knowledge.

Some theories suggest that dreams also have symbolic meanings that offer a glimpse into the unconscious mind. Keep reading to learn more about some of the best-known theories about why we dream.

7 Theories on Why We Dream

A dream theory focuses on understanding the nature and purpose of dreams. Studying dreams can be challenging since they can vary greatly in how they are remembered and what they are about.

Dreams include the images, thoughts, and emotions that are experienced during sleep. They can range from extraordinarily intense or emotional to very vague, fleeting, confusing, or even boring.

Some dreams are joyful, while others are frightening or sad. Sometimes dreams seem to have a clear narrative, while many others appear to make no sense at all.

There are many unknowns about dreaming and sleep, but what scientists do know is that just about everyone dreams every time they sleep, for a total of around two hours per night, whether they remember it upon waking or not .

Beyond what's in a particular dream, there is the question of why we dream at all. Below, we detail the most prominent theories on the purpose of dreaming and how these explanations can be applied to specific dreams.

How Do Scientists Study Dreams?

The question of why we dream has fascinated philosophers and scientists for thousands of years. Traditionally, dream content is measured by the subjective recollections of the dreamer upon waking. However, observation is also accomplished through objective evaluation in a lab.

In one study, researchers even created a rudimentary dream content map that was able to track what people dreamed about in real time using magnetic resonance imaging (MRI) patterns. The map was then backed up by the dreamers' reports upon waking.

What Dream Theory Suggests About the Role of Dreams

Some of the more prominent dream theories suggest that the reason we dream is to:

• Consolidate memories
• Process emotions
• Express our deepest desires
• Gain practice confronting potential dangers

Many experts believe that we dream due to a combination of these reasons rather than any one particular theory. Additionally, while many researchers believe that dreaming is essential to mental, emotional, and physical well-being, some scientists suggest that dreams serve no real purpose at all.

The bottom line is that while many theories have been proposed, no single consensus has emerged about which dream theory best explains why we dream.

Dreaming during different phases of sleep may also serve unique purposes. The most vivid dreams happen during rapid eye movement (REM) sleep , and these are the dreams that we're most likely to recall. We also dream during non-rapid eye movement (non-REM) sleep, but those dreams are known to be remembered less often and have more mundane content.

Sigmund Freud's Dream Theory

Sigmund Freud’s theory of dreams suggests that dreams represent  unconscious desires, thoughts, wish fulfillment, and motivations. According to Freud, people are driven by repressed and unconscious longings, such as aggressive and sexual instincts .

While many of Freud's assertions have been debunked, research suggests there is a dream rebound effect, also known as dream rebound theory, in which suppression of a thought tends to result in dreaming about it.

What Causes Dreams to Happen?

In " The Interpretation of Dreams ," Freud wrote that dreams are "disguised fulfillments of repressed wishes." He also described two different components of dreams: manifest content (actual images) and latent content (hidden meaning).

Freud’s theory contributed to the rise and popularity of dream interpretation . While research has failed to demonstrate that the manifest content disguises the psychological significance of a dream, some experts believe that dreams play an important role in processing emotions and stressful experiences.

Activation-Synthesis Dream Theory

According to the activation-synthesis model of dreaming , which was first proposed by J. Allan Hobson and Robert McCarley, circuits in the brain become activated during REM sleep, which triggers the amygdala and hippocampus to create an array of electrical impulses. This results in a compilation of random thoughts, images, and memories that appear while dreaming.

When we wake, our active minds pull together the dream's various images and memory fragments to create a cohesive narrative.  

In the activation-synthesis hypothesis, dreams are a compilation of randomness that appear to the sleeping mind and are brought together in a meaningful way when we wake. In this sense, dreams may provoke the dreamer to make new connections, inspire useful ideas, or have creative epiphanies in their waking lives.

Self-Organization Dream Theory

According to the information-processing theory, sleep allows us to consolidate and process all of the information and memories that we have collected during the previous day. Some dream experts suggest that dreaming is a byproduct, or even an active part, of this experience processing.  

This model, known as the self-organization theory of dreaming , explains that dreaming is a side effect of brain neural activity as memories are consolidated during sleep.

During this process of unconscious information redistribution, it is suggested that memories are either strengthened or weakened. According to the self-organization theory of dreaming, while we dream, helpful memories are made stronger, while less useful ones fade away.

Research supports this theory, finding improvement in complex tasks when a person dreams about doing them. Studies also show that during REM sleep, low-frequency theta waves were more active in the frontal lobe, just like they are when people are learning, storing, and remembering information when awake.

Creativity and Problem-Solving Dream Theory

Another theory about dreams says that their purpose is to help us solve problems. In this creativity theory of dreaming, the unconstrained, unconscious mind is free to wander its limitless potential while unburdened by the often stifling realities of the conscious world. In fact, research has shown dreaming to be an effective promoter of creative thinking.

Scientific research and anecdotal evidence back up the fact that many people do successfully mine their dreams for inspiration and credit their dreams for their big "aha" moments.

The ability to make unexpected connections between memories and ideas that appear in your dreams often proves to be an especially fertile ground for creativity.

Continuity Hypothesis Dream Theory

Under the continuity hypothesis, dreams function as a reflection of a person's real life, incorporating conscious experiences into their dreams. Rather than a straightforward replay of waking life, dreams show up as a patchwork of memory fragments.

Still, studies show that non-REM sleep may be more involved with declarative memory (the more routine stuff), while REM dreams include more emotional and instructive memories.

In general, REM dreams tend to be easier to recall compared to non-REM dreams.

Under the continuity hypothesis, memories may be fragmented purposefully in our dreams as part of incorporating new learning and experiences into long-term memory . Still, there are many unanswered questions as to why some aspects of memories are featured more or less prominently in our dreams.

Rehearsal and Adaptation Dream Theory

The primitive instinct rehearsal and adaptive strategy theories of dreaming propose that we dream to better prepare ourselves to confront dangers in the real world. The dream as a social simulation function or threat simulation provides the dreamer a safe environment to practice important survival skills.

While dreaming, we hone our fight-or-flight instincts and build mental capability for handling threatening scenarios. Under the threat simulation theory, our sleeping brains focus on the fight-or-flight mechanism to prep us for life-threatening and/or emotionally intense scenarios including:

• Running away from a pursuer
• Falling over a cliff
• Showing up somewhere naked
• Going to the bathroom in public
• Forgetting to study for a final exam

This theory suggests that practicing or rehearsing these skills in our dreams gives us an evolutionary advantage in that we can better cope with or avoid threatening scenarios in the real world. This helps explain why so many dreams contain scary, dramatic, or intense content.

Emotional Regulation Dream Theory

The emotional regulation dream theory says that the function of dreams is to help us process and cope with our emotions or trauma in the safe space of slumber.

Research shows that the amygdala , which is involved in processing emotions, and the hippocampus , which plays a vital role in condensing information and moving it from short-term to long-term memory storage, are active during vivid, intense dreaming.

This illustrates a strong link between dreaming, memory storage, and emotional processing.

This theory suggests that REM sleep plays a vital role in emotional brain regulation. It also helps explain why so many dreams are emotionally vivid and why emotional or traumatic experiences tend to show up on repeat. Research has shown a connection between the ability to process emotions and the amount of REM sleep a person gets.

Sharing Dreams Promotes Connection

Talking about content similarities and common dreams with others may help promote belongingness and connection. Research notes heightened empathy among people who share their dreams with others, pointing to another way dreams can help us cope by promoting community and interpersonal support.

Other Theories About Why We Dream

Many other theories have been suggested to account for why we dream.

• One dream theory contends that dreams are the result of our brains trying to interpret external stimuli (such as a dog's bark, music, or a baby's cry) during sleep.
• Another theory uses a computer metaphor to account for dreams, noting that dreams serve to "clean up" clutter from the mind, refreshing the brain for the next day.
• The reverse-learning theory suggests that we dream to forget. Our brains have thousands of neural connections between memories—too many to remember them all—and that dreaming is part of "pruning" those connections.
• In the continual-activation theory, we dream to keep the brain active while we sleep, in order to keep it functioning properly.

Overfitted Dream Hypothesis

One recently introduced dream theory, known as the overfitted dream hypothesis, suggests that dreams are the brain's way of introducing random, disruptive data to help break up repetitive daily tasks and information. Researcher Erik Hoel suggests that such disruptions helps to keep the brain fit.

Lucid dreams are relatively rare dreams where the dreamer has awareness of being in their dream and often has some control over the dream content. Research indicates that around 50% of people recall having had at least one lucid dream in their lifetime and just over 10% report having them two or more times per month.

It is unknown why certain people experience lucid dreams more frequently than others. While experts are unclear as to why or how lucid dreaming occurs, preliminary research signals that the prefrontal and parietal regions of the brain play a significant role.

How to Lucid Dream

Many people covet lucid dreaming and seek to experience it more often. Lucid dreaming has been compared to virtual reality and hyper-realistic video games, giving lucid dreamers the ultimate self-directed dreamscape experience.

Potential training methods for inducing lucid dreaming include cognitive training, external stimulation during sleep, and medications. While these methods may show some promise, none have been rigorously tested or shown to be effective.

A strong link has been found between lucid dreaming and highly imaginative thinking and creative output. Research has shown that lucid dreamers perform better on creative tasks than those who do not experience lucid dreaming.

Stressful experiences tend to show up with great frequency in our dreams. Stress dreams may be described as sad, scary, and nightmarish .

Experts do not fully understand how or why specific stressful content ends up in our dreams, but many point to a variety of theories, including the continuity hypothesis, adaptive strategy, and emotional regulation dream theories to explain these occurrences. Stress dreams and mental health seem to go hand-in-hand.

• Daily stress shows up in dreams : Research has shown that those who experience greater levels of worry in their waking lives and people diagnosed with post-traumatic stress disorder (PTSD) report higher frequency and intensity of nightmares.
• Mental health disorders may contribute to stress dreams : Those with mental health disorders such as anxiety, bipolar disorder , and depression tend to have more distressing dreams, as well as more difficulty sleeping in general.
• Anxiety is linked to stress dreams : Research indicates a strong connection between anxiety and stressful dream content. These dreams may be the brain's attempt to help us cope with and make sense of these stressful experiences.

While many theories exist about why we dream, more research is needed to fully understand their purpose. Rather than assuming only one dream theory is correct, dreams likely serve various purposes. In reality, many of these dream theories may be useful for explaining different aspects of the dreaming process.

If you are concerned about your dreams and/or are having frequent nightmares , consider speaking to your doctor or consulting a sleep specialist.

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By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Dream is not that which you see while sleeping it is something that does not let you sleep.

What's the meaning of this quote?

Quote Meaning: This thought-provoking quote redefines the concept of a dream, emphasizing its power to inspire and drive relentless pursuit.

Awake and Asleep Dreams: The quote distinguishes between two kinds of dreams: those that occur in our sleep, which are often random and fleeting, and those that are persistent and compelling, which don't allow us to sleep soundly.

Relentless Pursuit: It suggests that the most meaningful dreams are the ones that keep us awake at night, filling us with passion and purpose. These dreams are not passive fantasies but active motivations that drive us to take action.

Unwavering Commitment: The quote underscores the idea that pursuing a dream is not always easy. It may require sacrifices and tireless effort. However, it's this unwavering commitment that distinguishes a meaningful dream from a fleeting one.

Source of Inspiration: It also highlights the transformative power of a compelling dream, as it can motivate individuals to push their boundaries, strive for excellence, and achieve remarkable things.

In essence, this quote encourages individuals to seek dreams that are so compelling and meaningful that they become a driving force in their lives. It suggests that true dreams are not passive, ephemeral thoughts but rather powerful inspirations that keep individuals awake at night, pushing them to take action and pursue their aspirations with unwavering determination.

Who said the quote?

The quote "Dream is not that which you see while sleeping it is something that does not let you sleep." is often attributed to A. P. J. Abdul Kalam ( Bio / Quotes ) . A. P. J. Abdul Kalam was an Indian scientist and politician who served as the President of India from 2002 to 2007.

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Tallis in Wonderland

Notes towards a philosophy of sleep, raymond tallis takes us from a to zzzzz..

The column you’re reading is at least in part the result of an accident – a happy one, I hasten to add. A few weeks ago, I was sitting on a panel with the philosopher Christopher Hamilton, discussing the question of whether a world without pain is an appropriate goal for mankind or whether pain serves some additional positive purpose other than the obvious biological one of directing us away from things that might harm us (a topic, perhaps, for a future column). Meeting Christopher after a long interval reminded me of his excellent book Living Philosophy: Reflections on Life, Meaning and Morality (2001). The volume includes a fascinating essay entitled ‘The Need to Sleep’, where he notes that philosophers have not paid sufficient attention to this extraordinary phenomenon. Well, a decade on, this is the beginning of a response to Christopher’s wake-up call.

For sleep is rather extraordinary. If I told you that I had a neurological disease which meant that for eight or more hours a day I lost control of my faculties, bade farewell to the outside world, and was subject to complex hallucinations and delusions – such as being chased by a grizzly bear at Stockport Railway Station – you would think I was in a pretty bad way. If I also claimed that the condition was infectious, you would wish me luck in coping with such a terrible disease, and bid me a hasty farewell.

Of course, sleep is not a disease at all, but the condition of daily (nightly) life for the vast majority of us. The fact that we accept without surprise the need for a prolonged black-out as part of our daily life highlights our tendency to take for granted anything about our condition that is universal. We don’t see how strange sleep is because (nearly) everyone sleeps. Indeed, the situation of those who do not suffer from Tallis’s Daily Hallucinating Delusional Syndrome is awful. They have something that truly deserves our sympathy: chronic insomnia.

Since all animals sleep, we assume it has a biological purpose. The trouble is, we don’t know what that purpose is. There are many theories – energy conservation, growth promotion, immobilisation during hours of darkness when it might be dangerous to be out and about, consolidation of memories – but they are all open to serious objections. William Dement, one of the leading researchers of the last century and co-discoverer of Rapid Eye Movement sleep, concluded from his fifty years in the forefront of the field that “the only reason we need to sleep that is really, really solid, is that we get sleepy.”

Philosophers Asleep

It is easy to see why philosophers have, on the whole, avoided talking about sleep. Those who see the aim of philosophy as being to cultivate the most unpeeled mode of wakefulness are likely to treat sleep as an enemy. Hypnophobia was a striking theme in Existentialist thought. “Blessed are the sleepy ones” Nietzsche said sarcastically, “for they shall soon drop off.” And he sometimes endeavoured to do without sleep, on one occasion trying to live on four hours sleep a night for a fortnight. (I read this unimpressed when I was a junior doctor in the 1970s, and my 104-hour-week included periods of up to 48 hours continuously on call.) Jean-Paul Sartre’s Antoine Roquentin, the anti-hero of Sartre’s Nausea (1938), expresses his contempt for the landlord of the café he frequents by observing that “when this man is alone, he falls asleep.” And a character in one of his other novels observes with horror the person opposite him on the train, fast asleep, passively swaying in time to the movement of the carriage, reduced to a material object. This continuation of our lives in the absence of our waking self, in which the living daylights are replaced by the half-living nightlights, is a creepy reminder of the unchosen automatisms upon which our chosen lives depend.

Not only is sleep a reminder of our ultimate helplessness, or even of how circumscribed a place thought sometimes plays in our lives, there is also the fear of contagion, as if talking about sleep might induce it – just as this reference to yawning will get at least 50% of you yawning in the next 15 minutes. (It’s a fact, honest!)

Of course, there is no reason why the mind should not think about its antithesis, nor why super-mindful philosophers should not take an interest in our regular spells of compulsory mindlessness. After all, physicists have devoted much of their extraordinarily brilliant intellectual exertions to clarifying the nature of matter – of what is there, stripped of the kinds of meanings that fill their own consciousnesses. Philosophers, however, have a particular fear of one kind of sleep: the sleep that their own works may induce. Those carefully crafted arguments, the painstakingly revised sentences, expressing insights, so they hope, into the most fundamental aspects of the world, seem less able than a strip cartoon or a gossip column to hold back the reader from a world-dissolving snooze. Honest philosophers know they cannot complain about casting their philosophical pearls before drowsy swine, because they, too, have fallen asleep over the works of philosophers greater than themselves. I speak as a minor player who has sometimes dozed off while reading Heidegger’s Being and Time – possibly the greatest philosophical work of the last century, and the subject of a monograph I published a decade ago, and over which others too have dozed off. On other occasions I have woken with a start to discover that Kant’s Critique of Pure Reason has fallen from my slackening hand. There could be no more profound critique of reason, pure or impure.

For Descartes, cessation of thinking meant ceasing to be an ‘I’, so thoughtless sleep was vexing indeed – a vegetable, organic gap in our spiritual life. As James Hill (to whom I owe most of the contents of this paragraph) pointed out in ‘The Philosophy of Sleep: Descartes, Locke and Leibniz’ (in The Richmond Journal of Philosophy , Spring 2004), Descartes’ view of the mind as a substance did not allow for any pause in the continuity of thought. If the mind were the kind of thing that could be extinguished by the sound of a lecturer’s voice and rekindled by a wet flannel, it would not be worthy of the status of a substance, which should be immune from mere accidents. Descartes therefore concluded that we never stop thinking, even in the deepest sleep; however, in our deepest sleep we do not lay down any memories of our thoughts. Ad hoc or what?

John Locke would have none of it. Empirical evidence, he says, tells us that we do not think when asleep, and that’s the end of the story: “every drowsy Nod shakes [the Cartesian] Doctrine.” Leibniz, anticipating the confusions of Herr Professor Freud, argued that Descartes was right: we are thinking during dreamless sleep, but our thoughts are unconscious – rather like the perceptions we have without noticing them. I leave the reader to referee the discussion, but its unsatisfactory nature offers another reason why most philosophers have shied away from sleep.

Dreams, of course, have figured more significantly in philosophy. Being a mode of consciousness – prompting Aristotle to say that “the soul makes assertions in sleep” ( On Dreams 458b) – dreams seem one step up from the mere putting out of zzzs. More to the point, they place a philosophically interesting question mark against our confidence in the nature of the world we appear to share with others. Your dreams as you are dreaming them may be as compellingly real as the fact that you are reading this article (and possibly dozing off over it). “There are no certain indications” as Descartes pointed out in his Meditations , “by which I can clearly distinguish wakefulness from sleep.” The glib response to this – that we should not be looking for mere ‘indications’, because we do not rely on these kinds of things to find out whether we are awake or sleep – doesn’t work; and so we are embarked on an endless, and endlessly fascinating, journey in pursuit of the kind of certainty that only our philosophical selves want, or pretend to want, or need, or seem to need.

There is a kind of pathos to our vulnerable, gullible, sleeping selves, and the dreams that something that is ourself and yet not ourself puts together in order to make narrative sense of what is going on in our brains and bodies when they are almost completely disconnected from the world. To meet our insatiable appetite for coherent meaning, we unpack a whole scene out of a sensation, say, or make sense of a sudden movement of a limb by inventing a cliff down which we are falling. The fact that we can make a sort of sense out of whatever is served up to us is an interesting sidelight on the question of the relationship between the real and the rational: whatever we can rationalise may seem real to us, and whatever seems real to us we try to rationalise – with impressive rates of success. The division within our (mind-constructed) dreams between the ‘I’ that is making sense of what is there, and the ‘there’ that is made sense of – so that we can even wait tensely for what happens next – is particularly striking.

The great French poet and thinker Paul Valéry invented the character Monsieur Teste. ‘A mystic without God’, Teste was committed to uninterrupted, undistracted thought. His whole life’s work was “to kill the puppet,” the automaton, inside himself. In the famous An Evening With M. Teste (1896), Valéry leaves his hero drifting off to sleep, observing the stages of his own gradual extinction, and murmuring “Let’s think very closely… You can fall asleep on any subject… Sleep can continue any idea…” as his self-awareness fades into suspension points. Valéry himself kept a diary for over fifty years (collected as the Cahiers [Notebooks]). One of his central concerns was to observe the successive phases of his awakening, as in the early hours of the morning he annotated his mind-rise. Naturally, dreams preoccupied him as much as the daily resurrection of the self. He suggested that dreams might be an attempt to make sense of the body’s passage from sleep to wakefulness. Like me, he was unimpressed by Freud’s evidence-impoverished claims about dreams being the ‘royal road to the unconscious’ – that multi-storied jerry-built word-castle which so many otherwise intelligent people have taken for a scientific idea. Nor did Valéry buy the notion that dreams could be prophetic, the mind slipping along loops in time to enable us to see the future of the world or the will of God.

These nightly adventures, spun out of a consciousness permitted to free-wheel by disconnexion from a perceived world, are of compelling interest when we are in the grip of them as lead actor or as the helpless centre of events. Yet by an irony, nothing is more sleep-inducing than the egocentric tales of someone else’s solipsistic dreams. We long to hear that magic phrase “And then I woke up.”

I could go on, but I won’t, lest I cause your copy of Philosophy Now to fall from your lifeless hands as you slip from the philosophy of sleep to the thing itself…

© Prof. Raymond Tallis 2012

Raymond Tallis is a physician, philosopher, poet, broadcaster and novelist. His latest book In Defence of Wonder is just out from Acumen.

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Essays About Dreams In Life: 14 Examples And Topic Ideas

Dreams in life are necessary; if you are writing essays about dreams in life, you can read these essay examples and topic ideas to get started.

Everyone has a dream – a big one or even a small one. Even the most successful people had dreams before becoming who they are today. Having a dream is like having a purpose in life; you will start working hard to reach your dream and never lose interest in life.

Without hard work, you can never turn a dream into a reality; it will only remain a desire. Level up your essay writing skills by reading our essays about dreams in life examples and prompts and start writing an inspiring essay today!

Writing About Dreams: A Guide

Essays about dreams in life: example essays, 1. chase your dreams: the best advice i ever got by michelle colon-johnson, 2. my dream, my future by deborah massey, 3. the pursuit of dreams by christine nishiyama, 4. my dreams and ambitions by kathy benson, 5. turning big dreams into reality by shyam gokarn, 6. my hopes and dreams by celia robinson, 7. always pursue your dreams – no matter what happens by steve bloom, 8. why do we dream by james roland, 9. bad dreams by eli goldstone, 10. why your brain needs to dream by matthew walker, 11. dreams by hedy marks, 12. do dreams really mean anything by david b. feldman, 13. how to control your dreams by serena alagappan, 14. the sunday essay: my dreams on antidepressants by ashleigh young, essays about dreams in life essay topics, 1. what is a dream, 2. what are your dreams in life, 3. why are dreams important in life, 4. what are the reasons for a person to dream big, 5. what do you think about dreams in life vs. short-term sacrifice, 6. what is the purpose of dreaming, 7. why are dreams so strange and vivid, 8. why do dreams feel so real, 9. why are dreams so hard to remember, 10. do dreams mean anything, what is a dream short essay, how can i write my dream in life.

Writing about dreams is an excellent topic for essays, brainstorming new topic ideas for fiction stories, or just as a creative outlet. We all have dreams, whether in our sleep, during the day, or even while walking on a sunny day. Some of the best ways to begin writing about a topic are by reading examples and using a helpful prompt to get started. Check out our guide to writing about dreams and begin mastering the art of writing today!

“Everyone has the ability to dream, but not everyone has the willingness to truly chase their dreams. When people aren’t living their dreams they often have limited belief systems. They believe that their current circumstances and/or surroundings are keeping them from achieving the things they want to do in life.”

In her essay, author Michelle Colon-Johnson encourages her readers to develop a mindset that will let them chase their dreams. So, you have to visualize your dream, manifest it, and start your journey towards it! Check out these essays about dreams and sleep .

“At the time when I have my job and something to make them feel so proud of me, I would like to give them the best life. I would like to make them feel comfortable and see sweet smiles on their faces. This is really the one I like to achieve in my life; mountains of words can’t explain how much I love and appreciate them.”

Author Deborah Massey’s essay talks about her dreams and everything she wanted to achieve and accomplish in her life. She also tells us that we must live our values, pursue our dreams, and follow our passions for the best future.

“Fast-forward 5+ years, and my first published book is coming out this May with Scholastic. And now, let me tell you the truth: I don’t feel any different. I’m extremely grateful for the opportunity, proud of the work I’ve done, and excited for the book’s release. But on a fundamental level, I feel the same.”

In her essay, author Christine Nishiyama shares what she felt when she first achieved one of her goals in life. She says that with this mindset, you will never feel the satisfaction of achieving your goal or the fulfillment of reaching your dream. Instead, she believes that what fulfills people is the pursuit of their dreams in life.

“My dream is to become a good plastic surgeon and day after day it has transformed into an ambition which I want to move towards. I do not want to be famous, but just good enough to have my own clinic and work for a very successful hospital. Many people think that becoming a doctor is difficult, and I know that takes many years of preparation, but anyone can achieve it if they have determination.”

Author Kathy Benson’s essay narrates her life – all the things and struggles she has been through in pursuing her dreams in life. Yet, no matter how hard the situation gets, she always convinces herself not to give up, hoping her dreams will come true one day. She believes that with determination and commitment, anyone can achieve their dreams and goals in life. 

“I have always been a big dreamer and involved in acting upon it. Though, many times I failed, I continued to dream big and act. As long as I recollect, I always had such wild visions and fantasies of thinking, planning, and acting to achieve great things in life. But, as anyone can observe, there are many people, who think and work in that aspect.”

In his essay, author Shyam Gokarn explains why having a big dream is very important in a person’s life. However, he believes that the problem with some people is that they never hold tight to their dreams, even if they can turn them into reality. As a result, they tend to easily give up on their dreams and even stop trying instead of persevering through the pain and anguish of another failure.

“When I was younger, I’ve always had a fairytale-like dream about my future. To marry my prince, have a Fairy Godmother, be a princess… But now, all of that has changed. I’ve realized how hard life is now; that life cannot be like a fairy tale. What you want can’t happen just like that.”

Celia Robinson’s essay talks about her dream since she was a child. Unfortunately, as we grow old, there’s no “Fairy Godmother” that would help us when things get tough. Everyone wants to succeed in the future, but we have to work hard to achieve our dreams and goals.

“Take writing for example. I’ve wanted to be a professional writer since I was a little boy, but I was too scared that I wouldn’t be any good at it. But several years ago I started pursuing this dream despite knowing how difficult it might be. I fully realize I may not make it, but I’m completely fine with that. At least I tried which is more than most people can say.”

In his essay, author Steve Bloom encourages his readers always to pursue their dreams no matter what happens. He asks, “Would you rather pursue them and fail or never try?”. He believes that it’s always better to try and fail than look back and wonder what might have been. Stop thinking that failure or success is the only end goal for pursuing your dreams. Instead, think of it as a long journey where all the experiences you get along the way are just as important as reaching the end goal.

“Dreams are hallucinations that occur during certain stages of sleep. They’re strongest during REM sleep, or the rapid eye movement stage, when you may be less likely to recall your dream. Much is known about the role of sleep in regulating our metabolism, blood pressure, brain function, and other aspects of health. But it’s been harder for researchers to explain the role of dreams. When you’re awake, your thoughts have a certain logic to them. When you sleep, your brain is still active, but your thoughts or dreams often make little or no sense.”

Author James Roland’s essay explains the purpose of having dreams and the factors that can influence our dreams. He also mentioned some of the reasons that cause nightmares. Debra Sullivan, a nurse educator, medically reviews his essay. Sullivan’s expertise includes cardiology, psoriasis/dermatology, pediatrics, and alternative medicine. For more, you can also see these articles about sleep .

“The first time I experienced sleep paralysis and recognised it for what it was I was a student. I had been taking MDMA and listening to Django Reinhardt. My memories of that time are mainly of taking drugs and listening to Django Reinhardt. When I woke up I was in my paralysed body. I was there, inside it. I was inside my leaden wrists, my ribcage, the thick dead roots of my hair, the bandages of skin. This time the hallucinations were auditory. I could hear someone being beaten outside my door. They were screaming for help. And I could do nothing but lie there, locked inside my body . . . whatever bit of me is not my body. That is the bit that exists, by itself, at night.”

In her essay, Author Eli Goldstone talks about her suffering from bad dreams ever since childhood. She also talks about what she feels every time she has sleep paralysis – a feeling of being conscious but unable to move.

“We often hear stories of people who’ve learned from their dreams or been inspired by them. Think of Paul McCartney’s story of how his hit song “Yesterday” came to him in a dream or of Mendeleev’s dream-inspired construction of the periodic table of elements. But, while many of us may feel that our dreams have special meaning or a useful purpose, science has been more skeptical of that claim. Instead of being harbingers of creativity or some kind of message from our unconscious, some scientists have considered dreaming to being an unintended consequence of sleep—a byproduct of evolution without benefit.”

Author Matthew Walker, a professor of psychology and neuroscience, shares some interesting facts about dreams in his essay. According to research, dreaming is more than just a byproduct of sleep; it also serves essential functions in our well-being. 

“Dreams are basically stories and images that our mind creates while we sleep. They can be vivid. They can make you feel happy, sad, or scared. And they may seem confusing or perfectly rational. Dreams can happen at any time during sleep. But you have your most vivid dreams during a phase called REM (rapid eye movement) sleep, when your brain is most active. Some experts say we dream at least four to six times a night.”

In his essay, Author Hedy Marks discusses everything we need to know about dreams in detail – from defining a dream to tips that may help us remember our dreams. Hedy Marks is an Assistant Managing Editor at WebMD , and Carol DerSarkissian, a board-certified emergency physician, medically reviews his essay.

“Regardless of whether dreams foretell the future, allow us to commune with the divine, or simply provide a better understanding of ourselves, the process of analyzing them has always been highly symbolic. To understand the meaning of dreams, we must interpret them as if they were written in a secret code. A quick search of an online dream dictionary will tell you that haunted houses symbolize “unfinished emotional business,” dimly lit lamps mean you’re “feeling overwhelmed by emotional issues,” a feast indicates “a lack of balance in your life,” and garages symbolize a feeling of “lacking direction or guidance in achieving your goals.” 

Author David B. Feldman, an author, speaker, and professor of counseling psychology, believes that dreams may not mean anything, but they tell us something about our emotions. In other words, if you’ve been suffering from a series of bad dreams, it could be worth checking in with yourself to see how you’ve been feeling and perhaps consider whether there’s anything you can do to improve your mood.

“Ever wish you could ice skate across a winter sky, catching crumbs of gingerbread, like flakes of snow, on your tongue? How about conquering a monster in a nightmare, bouncing between mountain peaks, walking through walls, or reading minds? Have you ever longed to hold the hand of someone you loved and lost? If you want to fulfill your fantasies, or even face your fears, you might want to try taking some control of your dreams (try being the operative). People practiced in lucid dreaming—the phenomenon of being aware that you are dreaming while you are asleep—claim that the experience allows adventure, self-discovery, and euphoric joy.”

In her essay, Author Serena Alagappan talks about lucid dreams – a type of dream where a person becomes conscious during a dream. She also talked about ways to control our dreams, such as keeping a journal, reciting mantras before bed, and believing we can. However, not everyone will be able to control their dreams because the levels of lucidity and control differ significantly between individuals.

“There was a period of six months when I tried to go off my medication – a slowly unfolding disaster – and I’d thought my dreams might settle down. Instead, they grew more deranged. Even now I think of the dream in which I was using a cigarette lighter to melt my own father, who had assumed the form of a large candle. I’ve since learned that, apart from more research being needed, this was probably a case of “REM rebound”. When you stop taking the medication, you’ll likely get a lot more REM sleep than you were getting before. In simple terms, your brain goes on a dreaming frenzy, amping up the detail.”

Author Ashleigh Young’s essay informs us how some medications, such as antidepressants, affect our dreams based on her own life experience. She said, “I’ve tried not to dwell too much on my dreams. Yes, they are vivid and sometimes truly gruesome, full of chaotic, unfathomable violence, but weird nights seemed a reasonable price to pay for the bearable days that SSRIs have helped me to have.” 

In simple terms, a dream is a cherished aspiration, ambition, or ideal; is it the same as your goal in life? In your essay, explore this topic and state your opinion about what the word “dream” means to you.

This is an excellent topic for your statement or “about me” essay. Where do you see yourself in the next ten years? Do you have a career plan? If you still haven’t thought about it, maybe it’s time to start thinking about your future.

Having dreams is very important in a person’s life; it motivates, inspires, and helps you achieve any goal that you have in mind. Without dreams, we would feel lost – having no purpose in life. Therefore, in your essay, you should be able to explain to your readers how important it is to have a dream or ambition in life. 

Dreaming big sounds great; however, it’s easier said than done. First, you’ve got to have reasons to dream big, which will motivate you to achieve your goals in life. If you’re writing an essay about dreams in life, mention why most people dare to dream big and achieve more in life. Is it about freedom, money, praise from other people, satisfaction, or something else entirely?

For example, you could watch movies, play video games, relax every night, or give up all of them to learn a complex skill – what would you choose, and why? In your essay about dreams in life, answer the question and include other examples about this topic so your readers can relate.

There are many answers to this question – one is that dreams may have an evolutionary function, testing us in scenarios crucial to our survival. Dreams may also reduce the severity of emotional trauma. On the other hand, some researchers say dreams have no purpose or meaning, while some say we need dreams for physical and mental health. Take a closer look at this topic, and include what you find in your essay.

Weird dreams could result from anxiety, stress, or sleep deprivation. So, manage your stress levels, and stick to a sleep routine to stop having weird dreams. If you wake up from a weird dream, you can fall back asleep using deep breaths or any relaxing activity. You can research other causes of weird dreams and ways to stop yourself from having them for your essay about dreams and sleep.

The same areas of the brain that are active when we learn and process information in the actual world are active when we dream, and they replay the information as we sleep. Many things we see, hear, and feel in our everyday lives appear in our dreams. If you want to write an informative essay about dreams and sleep, look into more details about this topic.

Tip: When editing for grammar, we also recommend taking the time to improve the readability score of a piece of writing before publishing or submitting it.

People may not remember what happened in their dreams. Studies show that people tend to forget their dreams due to the changing levels of acetylcholine and norepinephrine during sleep. This will be quite an exciting topic for your readers because many people can relate. That being said, research more information about this topic, and discuss it in detail in your essay. 

Although some people believe that dreams don’t mean anything, many psychologists and other experts have theorized about the deeper meaning of dreams. Therefore, your essay about dreams and sleep should delve deeper into this topic. If you’re stuck picking your next essay topic, check out our round-up of essay topics about education .

FAQS on Essays About Dreams in Life

There are many great short essays about dreams; you can write your own too! Some great examples include Do Dreams Really Mean Anything? by David B. Feldman and  Dreams by Hedy Marks.

Writing about your dreams in life is a fantastic creative outlet and can even help you plan your future. Use a prompt to get started, like “What are your dreams in life?” or “What do you aspire to be in ten years?” and begin writing without thinking too much about it. See where the pen takes you and start mapping out your future with this writing exercise.

Meet Rachael, the editor at Become a Writer Today. With years of experience in the field, she is passionate about language and dedicated to producing high-quality content that engages and informs readers. When she's not editing or writing, you can find her exploring the great outdoors, finding inspiration for her next project.

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Understanding Dreams

Reviewed by Psychology Today Staff

Dreams are imaginary sequences—some with clear narratives, and some without—that play out in people’s minds as they sleep. Most dreams consist of a series of images, sensations, and emotions, and range from pleasant and exciting to boring or even terrifying.

Dreams have long captured the imagination of humankind; early in recorded history, they were thought to be messages from deities or a means to predict the future. In more recent years, they have drawn the focus of psychologists, neurologists, philosophers, and biologists, all of whom continue to study dreams, what they mean, and why dreaming is necessary for humans and animals alike.

7 surprising facts about dreams — why we have them and what they mean

Andrea Muraskin

An abstract 3d cloud model in the bedroom. (3d render) Eoneren/Getty Images/E+ hide caption

I had a nightmare last night.

It began like many of my dreams do – I was on vacation with my extended family. This time, we were in Australia, visiting family friends in a big house. Things took a turn when — in some way that I can’t quite explain — I got mixed up in this Australian family’s jewelry theft and smuggling operation. And I lied about it in front of my relatives, to protect myself and my co-conspirators. Before I woke up, I was terrified I’d be sent to prison.

The dream seems bizarre, but when I pick the narrative apart, there are clear connections to my waking life. For instance, I recently listened to a podcast where a pair of fancy hairpins suspiciously go missing during a family gathering. Moreover, I’m moving tomorrow and still have packing to do. When the movers arrive in the morning, if I haven't finished packing, I'll face the consequences of my lack of preparedness – a crime, at least to my subconscious.

This story also appears in the June 2 issue of the NPR Health newsletter. Click here to subscribe.

Dr. Rahul Jandial, neurosurgeon, neuroscientist and author of This is Why You Dream: What Your Sleeping Brain Reveals About Your Waking Life , says the major themes and images of vivid dreams like these are worth paying attention to, and trying to derive meaning from. (For me, I decided that the next time I have to move, I’m taking the day before off!)

Dr. Rahul Jandial Sam Lim/Penguin Random House hide caption

I spoke with Dr. Jandial about what else we can learn from our dreams, including some of modern science’s most remarkable findings, and theories, about the dreaming brain.

1. Dreams are not random

From dream diaries recorded in ancient Egypt and China to reports from anthropologists in the Amazon, to surveys of modern Americans, evidence shows our dreams have a lot in common. For example, being chased and falling are pretty consistent.

“Reports of nightmares and erotic dreams are nearly universal,” Jandial says, while people rarely report dreaming about math. Jandial says the lack of math makes sense because the part of your brain primarily responsible for logic — the prefrontal cortex — is typically not involved in dreaming.

2. Our brains are super active when we dream

Jandial learned something fundamental about dreams in the midst of performing brain surgery.

It was awake surgery – he’d numbed the scalp and partially opened the skull. (The brain does not feel pain). Jandial was operating on the left temporal lobe, where language is typically located. Working carefully to avoid damage, he went millimeter by millimeter, stimulating the neurons, and asking the patient to count to ten at each spot.

But after one such zap of electricity, Jandial’s patient experienced a nightmare that had recurred for him since childhood.

Research has since confirmed that nightmares, and all dreams, arise from brain activity. “Now we know from different measurements of electricity and metabolic usage, the sleeping-dreaming brain is burning hot. It's sparking with electricity. We might be asleep, but the brain is on fire,” Jandial says.

3. When you first wake up, or while you're drifting off, is fertile time for creativity

Salvador Dali had a method for capturing his thoughts just as he was falling asleep, which Jandial recounts in This is Why You Dream . The artist would sit in a chair holding a large key above a plate on the floor. When he nodded off, the key would drop on the plate and wake him up. Then he’d sketch what he remembered from the last few moments of sleep – an inspiration for his surrealist paintings. Brain imaging studies support the potential of sleep-entry as a moment of insight, says Jandial.

Fortunately for those of us who prefer to fall asleep and stay there, thank you very much, you can also get inspiration from your dreams when you first wake up. “I get all my ideas when I wake slowly,” Jandial says. He writes down what he remembers in the first few minutes after waking, before checking the news or Instagram. It’s not all great stuff, “But when there are good ideas, it's from that time. It's not from two o'clock with my espresso,” he says.

4. Nightmares? Write a new script

Jandial says nightmares around occasional stressful events, like my dream about the jewelry heist – are usually not cause for concern. But if you’re stuck in a loop of recurring fearful dreams, there is something you can try: Imagery Rehearsal Therapy.

This is something you can do with a therapist. “If [a patient has] a recurrent nightmare of an explosion or an airplane crashing, they'll go to the therapist to draw out the map of the dream, the dreamscape, if you will, and then they'll rehearse that the airplane landed safely,” or that they arrived home from a drive instead of crashing, Jandial explains. After time, he says many patients see their nightmares change.

5. Dreams about cheating are normal. They don’t mean there's something wrong with your relationship

In surveys, a majority of people report erotic dreams. And for people in relationships, these dreams contain “high rates of infidelity, whether people report being in healthy relationships or unhealthy relationships,” Jandial says.

But sexy dreams have rules too. “When you look at the pattern of erotic dreams, the acts seem to be wild, but the characters are surprisingly narrow. Celebrities, even family members, repellent bosses; it's a small collection of people as a pattern.” Jandial and others theorize that having sexual dreams about people familiar to us may be a feature our brains evolved to keep us open to procreation and increase the likelihood of the species’ survival.

6. Near the end of life, dreams can provide comfort

Treating patients at City of Hope cancer center in Los Angeles, Jandial observes a phenomenon he calls “dreams to the rescue.” For some patients near the end of their lives, “even though the day is filled with struggle, the dreams are of reconciliation, of hope, of positive emotions. I was surprised to find that end-of-life dreams are a common thing, and they lean positive.”

Jandial says there’s evidence that death may come with one final dream. “Once the heart stops, with the last gush of blood up the carotid [artery] to the brain, the brain's electricity explodes in the minute or two after cardiac death…Those patterns look like expansive electrical brainwave patterns of dreaming and memory recall,” Jandial says.

7. Dreams can be ‘a portal to your inner self’ — and mental health

Everyone has anxiety dreams from time to time. Some are literal, like dreaming you’re on a podium naked when you actually have to give a speech the next day, says Jandial. But others can be more symbolic, and these are worth tuning in to.

Jandial remembers one he had during the pandemic. In waking life, he’d just learned to sail. In the dream he was sailing a boat and, “there was a massive waterfall,” he recounts. “And I was sailing horizontally and I had to constantly keep the helm, or the wheel, up-river just to go straight and not fall off.”

He interprets it as his brain’s way of helping him process a difficult time. He was raising teenagers and working as a cancer surgeon amid COVID fears. “There were wars on many fronts for me at that time. And what I walked away with is just by avoiding going all over the waterfall, you're doing it.”

He says if you have a powerful dream, it’s worth thinking about why. “Dreams with a strong emotion and a powerful central image, those are ones not to ignore,” he says. “The dreaming brain is serving a function, and if it gives you a nugget of an emotional and visual dream, reflect on that. That's a portal to yourself that no therapist can even get to.”

And repeated anxiety dreams, he says “I think that's something to pay attention to. That might be a vital sign for your mental health.”

Why Don’t I Dream: Unraveling the Science of Dreamless Sleep

• Fact Checked

Written by:

• Eliana Galindo

published on:

• June 5, 2024

Updated on:

• June 4, 2024

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Many individuals  wake up  after a night’s sleep wondering why they don’t seem to have any dreams.  Research  has shown that  everyone dreams , but the memory of those dreams is not guaranteed.

Dream recall  can be influenced  by various factors including sleep quality, stress levels, and even the timing of when one wakes up.

Understanding Dreams

Dreams are a  universal human experience , intricately linked to the complex functions of the brain during sleep. Investigating dreams leads us to a greater understanding of our cognition and emotional  processing .

The Science of Dreaming

Dreams predominantly occur during  REM (Rapid Eye Movement) sleep , a phase of the sleep cycle characterized by rapid eye movements, increased brain activity, and muscle paralysis.

It is during REM sleep that dreams recall—the ability to remember dreams— is  most likely , although dreaming can occur at any sleep stage.

Studies  have shown that the  neuroscience   behind  dreaming involves various brain regions, such as the amygdala, which processes emotions, and the hippocampus, involved in  memory consolidation .

Vivid dreams  are associated with increased activity in these regions, which indicates a strong connection between dreaming and the subconscious.

During sleep, the  sleep cycle  repeats multiple times, and dreams can become more vivid and easier to remember during the later cycles when REM periods are longer.

The Purpose of Dreams

Theories on the purpose of dreams range from  psychological to physiological , but all recognize their importance to human health.

One hypothesis is that dreams are a  way for the brain to process  emotions and subconscious thoughts, allowing for mental reconciliation and problem-solving. Dreams might also serve a  restorative function  for cognitive function, by clearing irrelevant information and strengthening relevant memories.

Lucid dreaming , where the dreamer is aware they are dreaming and can exert  some control over  the dream, is a unique state of dreaming that blends consciousness and dream states, showcasing the complex interrelationship between consciousness and the brain’s functions.

In this web of processes, dreams are  not merely nightly narratives  but fundamental to a person’s mental and emotional equilibrium.

Factors Affecting Dream Recall

Dream recall can be influenced by a complex interplay of physiological and psychological factors, each having a measurable impact on the ability to remember dreams.

Sleep Quality

If you don’t get enough sleep , especially deep sleep and REM sleep, it can affect your ability to dream. Frequent awakenings or sleep disruptions can hinder the dream cycle, making it harder to enter REM sleep.

In contrast, high-quality sleep , characterized by adequate duration and minimal disturbances, allows for more vivid and memorable dreams.

Health and Lifestyle

Overall health and daily lifestyle choices can directly affect dream recall. Regular exercise can improve sleep quality and thereby, potentially dream recall .

In contrast, consumption of alcohol or caffeine close to bedtime can disrupt sleep patterns and impair the ability to remember dreams.

Medications and Substances

Certain medications or drugs can alter dream frequency and recall. For example, some antidepressants can suppress REM sleep, reducing the likelihood of dream recall.

Moreover, alcohol and recreational drugs can impact the sleep cycle and suppress REM sleep, resulting in fewer dreams or difficulty recalling them.

Stress and Anxiety

High levels of stress and anxiety can impact sleep quality and may reduce the likelihood of dreaming or remembering dreams. Stress hormones can interfere with the normal sleep cycle.

Sleep Disorders

Sleep disorders such as insomnia can have a significant impact on an individual’s ability to remember dreams due to the erratic nature of their sleep patterns and the potential reduction in overall sleep quality.

Age is a factor in dream recall, with younger individuals typically having a higher frequency of dream recall than older adults, likely due to changes in sleep architecture and brain activity as one ages.

Enhancing Dream Recollection

Individuals may not always remember their dreams, but enhancing dream recall is possible through various techniques that promote memory consolidation.

Improve Your Sleep Hygiene

Quality sleep is essential for memory consolidation. Eliminating electronic devices before bed could help one experience uninterrupted sleep cycles, which are conducive to dream recall.

Other recommendations include :

• Regular Sleep Schedule: Go to bed and wake up at the same time every day to establish a consistent sleep pattern.
• Avoid Stimulants: Limit caffeine and alcohol intake, especially in the hours leading up to bedtime, as these can disrupt REM sleep.
• Create a Restful Environment: Ensure your bedroom is cool, dark, and quiet to promote better sleep quality.

Set an Intention

Before sleeping, setting a clear intention to remember dreams can be effective . Repeating phrases like “I will remember my dreams tonight” can set a mental expectation .

Psychologists note that this practice can prime the mind to focus on dream recollection, potentially enhancing the ability to remember dreams in the morning.

Use a Dream Journal

Keeping a dream journal by the bedside is a widely endorsed technique by psychologists for enhancing dream recall. Writing down dreams immediately upon waking helps solidify the memory.

It is helpful to record everything, even if it’s just fragmented pieces or emotions, as this can later trigger more detailed memories .

Stay Still Upon Waking

Minimizing physical activity immediately after waking can prevent the scattering of dream details.

By staying still, one allows their mind to focus on retrieving images and narratives from their dreams, which might otherwise fade away quickly.

Engage with Your Dreams

Engaging with dream content through discussions or creative activities may increase one’s ability to remember future dreams.

Psychologists believe that this engagement strengthens the cognitive pathways between dreaming and reality, which can enhance one’s recall abilities.

Activities like drawing scenes from a dream or sharing them with others can reinforce these memories .

When to Seek Help

One should consider seeking help if one notices persistent  issues related  to sleep or dreams that significantly affect their daily life.

Here are s pecific instances  and steps one can take to address their concerns.

Identifying Disorders Related to Dreams

Dreams can be affected by a variety of  health concerns , including  mental health disorders  such as anxiety or depression.

If one experiences a  noticeable change  in their dreaming patterns, such as an absence of dreams, it may be indicative of an underlying condition.

Sleep disorders, particularly  sleep apnea , are known to influence one’s ability to remember dreams and are associated with other symptoms like snoring and daytime fatigue.

Consulting with Healthcare Professionals

When symptoms are  persistent and concerning , consulting with healthcare professionals is a prudent step.

One may start with a primary care doctor who can provide an initial assessment and may refer to a  neurologist  or a  sleep specialist  for further testing.

These professionals can  evaluate symptoms  like stress, tension, and sleep-related medical issues to pinpoint the cause. For instance, excessive weight gain or obesity can be linked to sleep disturbances and might warrant an evaluation for sleep apnea.

If you  have symptoms  of  anxiety ,  depression ,  PTSD , or other mental health conditions that might affect your sleep and dream patterns,  therapy can be an essential  part of treatment.

To find a qualified and licensed therapist, you can  use online directories  such as  Find-a-therapist.com , which allows you to filter your search according to your needs. Another option is  BetterHelp , one of the largest  online therapy platforms .

Frequently Asked Questions

Is an absence of dreams indicative of a personality disorder.

An absence of dreams is not typically indicative of a personality disorder. Dreams are a normal part of sleep, and not remembering them is more common than one may think.

Could a lack of dreams be a symptom of depression?

While a lack of dreams is not a direct symptom of depression, changes in sleep patterns and the content of dreams can be associated with depression.

Individuals with depression may have difficulty remembering their dreams.

What do you call the condition where a person doesn’t experience dreams?

The condition where a person does not experience dreams is referred to as ‘dream deprivation’ or ‘dream loss.’

It should be noted, however, that most people do dream but may not always remember their dreams upon waking.

What could be the reasons for suddenly stopping dreaming?

A sudden cessation of dreams could be related to:

• Sleep deprivation
• Disruption of REM sleep
• Certain medications
• Changes in lifestyle

What does it signify if someone never experiences dreams?

If someone never experiences dreams, it may simply mean they do not recall dreaming. It’s rare for an individual to truly never dream, as dreaming is an important part of the REM cycle of sleep.

Herlin, B., Leu‐Semenescu, S., Chaumereuil, C., & Arnulf, I. (2015). Evidence that non‐dreamers do dream: A REM sleep behaviour disorder model.  Journal of sleep research ,  24 (6), 602-609. Link .

Hobson, J. A., & Pace-Schott, E. F. (2002). The cognitive neuroscience of sleep: neuronal systems, consciousness and learning.  Nature Reviews Neuroscience ,  3 (9), 679-693. Link .

Additional Resources

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Essay on Dreams which should not let India sleep

July 8, 2019 by Sandeep

T.E.Lawrence, a British archaeologist, army officer, diplomat and writer once said that, “all men dream, but not equally. Those who dream by night in the dusty recesses of their minds, wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act on their dreams with open eyes, to make them possible”.

This aptly sums up the real meaning of dream. Only those dreams come true which are nurtured with strength, patience and passion to reach for the stars to change the world. The dream a person dream alone is just a dream but, a dream if all Indian dreams together this will be termed as a reality.

India is struggling with many problems and it can only develop when all these problems are tackled with a strategy. And dream does not become reality through magic; it takes sweat, determination and hard work.

The dream of independence, which the citizen saw from open eyes, became true on 15th August, 1947. The 200 year long struggle ended with colours of victory. India has come a long way since independence. India is heading towards becoming successful and is working hard to influence other in the international field.

But, for becoming a super power, the country needs to strengthen itself internally and externally by removing the paradoxes that hampers the growth. There are several other problems which India is facing and we need to overcome them.

The dream of safety of women 

The status of women in ancient times was much better. Women during the Vedic period enjoyed equal status with men in all aspects of life. Works by ancient Indian grammarians such as Patanjali and Katyayana suggested that women were educated in the early Vedic period.

Along with the invasion of the country by the Muslims, the position of women declined further. In many cases the Hindu girls were given in marriage before the age of nine or ten. This also clearly indicated that the Hindu girls were denied education. In freedom struggle also, women were not given prominent place.

There were only few females who were given place in the freedom struggle. Today, there are many provisions in the Constitution of India, and government has formulated many laws from time to time for uplifting the status of women in India but proper implementation is still a dream.

We can now conceptualize and implement the cheapest way to reach mars but our girls fail to successfully complete the journey from a mother’s womb. Women are often subjected to domestic violence, lack of education, lack of medical resources, female feticide etc. Women are not safe whether they are inside the house or are working outside.

Rape the number of rape cases are increasing day by day. Even the parent who is liberal to their female child and wants to educate them hesitates to send them to big cities. Though the condition has improved, but women are not as independent as men. The government enacts laws to ensure that women get a proper system of redressal and their rights are not curbed. Some of these laws are:

• Prevention of Children from Sexual Offence Act, 2012
• The Domestic Violence Act, 2005
• Sexual Harassment of Women at Work Place Act, 2013

Corruption free country 

Every citizen is working hard today to achieve success, but some adopts a path which diverts them from the normal cause of action. The constitution provides equal opportunity to all irrespective of caste, colour, creed, sex etc. based on their skills and knowledge. But people use unfair means to achieve what the desires.

Corruption is rooted in every department of government and private sector. The political parties are involved in corruption. The virtues of honesty have declined. Those who are involved in corruption and related activities forget that they are satisfied in short run and in long run their life will be full of tensions.

The substantial deposits in the Swiss Bank are an example of black money. Today, the universities are also corrupt. They take handsome amount from those who do not deserve any seat. This valuable seat which should be given to a deserving candidate is wasted and sold for money. Corruption is a deeply rooted problem and we are its only solution. We should know the implications of it and should stop corruptions.

Terror free country 

The Pulwama attack, the Uri attack, the Naxalite the Mumbai attacks, attacks are a few examples that terrorism is a threat over the peace of the country. We are affected by the cross border terrorism. Infiltration of terrorists from Kashmir and Bangladesh border is generating a lot of violence and panic among people.

Our brave soldiers are losing their lives countering the enemy attacks. India already invest much in defense and related fields. These resources could have been applied somewhere else if terrorism was not the problem for the country. Terrorism is a global issue and nations are trying to counter this but there is still a need for an international body to counter the problem of terrorism. Therefore, we need a terror free society which can sleep peacefully.

The dream of being an economically prosperous nation

An economically prosperous nation is the one which has no poor population, equal opportunities to everyone, affordable access to basic amenities of life, a speedy health care facility at cheap rates, a power full currency, no problem of hoarding and inflation, availability of food for everyone etc.

Today India is the fastest growing economy of the world and has been ranked third according to the Gross Domestic Product. But this growth is also insufficient to reach the equitable distribution of income among its people. A large section of the society is still living under the poverty line. The agriculture product of India stands third in the world but still we encounter the problems of suicide and hunger of the farmers. These problems need special and urgent attention.

Education for all

The Government of India is trying its hardest to increase the literacy rate of the country, but even after putting all the efforts it still lack behind. The government started the Mid-day meal policy to attract more children and this strategy is getting a good response. But still there are many hurdles which stop children from coming to school.

Like in villages the girls are not allowed to go outside their houses and are taught to be good mothers. Small girls are married off at a tender age and their path of education is blocked with many other household responsibilities. The light of education is yet to be reached to grass root level of the society.

The education system of India is very theoretical which do not provide much opportunity for research works. We have the best institutions like the IIT, IIM, AIIMS etc which are capable of generating world class professionals but they also lacks in government funding for the purpose of research and development.

Healthy nation

Problem of hunger and malnutrition is a matter of concern. The conditions of the government hospitals are pitiable. There is no availability of proper facilities. The prices of health care at reputable institutions are reaching skies. People die every day due to lack of availability of medical aid.

Scientific and technology development 

The Mangalyaan mission is the first inter planetary mission which was successfully accomplished by the Indian technological developments. India accomplished this mission in its first attempt. This accomplishment brought glory to our nation. The missiles and other advancement has brought in a lot of praise from all over the world.

Though we did a lot in the field of technological and scientific development, still we lack behind the powers such as Russia and USA. We are dependent on other developed countries for weapons, machinery, aircraft’s, fighter planes, carriers etc.

The government needs to boost up creative thinking and encourage research and innovation. With the efforts of the government make in India movement, the country is making its first indigenous Air Craft Carrier 1 at Cochin Shipyard in Kochi. It is the first aircraft carrier to be built in India. This is just one example; the government has been encouraging the native people to develop in India.

Employment for all

The scarcity of employment is one of the major issues of the country. Ever year India is producing large amount of scholars but there is inadequate infrastructure to provide them job. The industrial sector needs to be developed so that the jobs increase and other ways to get jobs also open up.

We need to look into this problem and find solutions for it because the dream of equitable distribution of income and resources would never be accomplished.