Dreams and Dreaming

Dreams: Why do we dream?

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Why do dreams occur?

Can we control them? What do they mean? There are several theories about why we dream. Are dreams merely part of the sleep cycle, or do they serve some other purpose? From evidence and new research methodologies, researchers have speculated that dreaming serves the following functions:. Much that remains unknown about dreams. They are by nature difficult to study in a laboratory, but technology and new research techniques may help improve our understanding of dreams. Light sleep, slow eye movement, and reduced muscle activity. This stage forms 4 to 5 percent of total sleep. Eye movement stops and brain waves become slower, with occasional bursts of rapid waves called sleep spindles.

This stage forms 45 to 55 percent of total sleep. Extremely slow brain waves called delta waves begin to appear, interspersed with smaller, faster waves. This accounts for 4 to 6 percent of total sleep.

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The brain produces delta waves almost exclusively. It is difficult to wake someone during stages 3 and 4, which together are called "deep sleep. People awakened while in deep sleep do not adjust immediately and often feel disoriented for several minutes after waking up. This forms 12 to 15 percent of total sleep.

This stage is known as rapid eye movement REM. Breathing becomes more rapid, irregular, and shallow, eyes jerk rapidly in various directions, and limb muscles become temporarily paralyzed. Heart rate increases, blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales. This stage accounts for 20 to 25 percent of total sleep time. Neuroscience offers explanations linked to the rapid eye movement REM phase of sleep as a likely candidate for the cause of dreaming. Dreams are a universal human experience that can be described as a state of consciousness characterized by sensory, cognitive and emotional occurrences during sleep.

The dreamer has reduced control over the content, visual images and activation of the memory. There is no cognitive state that has been as extensively studied and yet as frequently misunderstood as dreaming.

There are significant differences between the neuroscientific and psychoanalytic approaches to dream analysis. Neuroscientists are interested in the structures involved in dream production, dream organization, and narratability. However, psychoanalysis concentrates on the meaning of dreams and placing them in the context of relationships in the history of the dreamer. Reports of dreams tend to be full of emotional and vivid experiences that contain themes, concerns, dream figures, and objects that correspond closely to waking life.

These elements create a novel "reality" out of seemingly nothing, producing an experience with a lifelike timeframe and connections. Nightmares are distressing dreams that cause the dreamer to feel a number of disturbing emotions. Common reactions to a nightmare include fear and anxiety. Lucid dreaming is the dreamer is aware that they are dreaming.

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They may have some control over their dream. This measure of control can vary between lucid dreams. They often occur in the middle of a regular dream when the sleeping person realizes suddenly that they are dreaming. Some people experience lucid dreaming at random, while others have reported being able to increase their capacity to control their dreams. For example, during exam time, students may dream about course content. People in a relationship may dream of their partner.

Web developers may see programming code. These circumstantial observations suggest that elements from the everyday re-emerge in dream-like imagery during the transition from wakefulness to sleep. Studies have examined the "characters" that appear in dream reports and how they the dreamer identifies them. A study of adult dream reports found:. Another study investigated the relationship between dream emotion and dream character identification. Affection and joy were commonly associated with known characters and were used to identify them even when these emotional attributes were inconsistent with those of the waking state.

The findings suggest that the dorsolateral prefrontal cortex, associated with short-term memory, is less active in the dreaming brain than during waking life, while the paleocortical and subcortical limbic areas are more active. The concept of 'repression' dates back to Freud. Freud maintained that undesirable memories could become suppressed in the mind. Dreams ease repression by allowing these memories to be reinstated.

Sleep Science: The Mystery of Dreams and Dreaming

A study showed that sleep does not help people forget unwanted memories. Instead, REM sleep might even counteract the voluntary suppression of memories, making them more accessible for retrieval. The findings of one study suggest that:. Dream-lag is when the images, experiences, or people that emerge in dreams are images, experiences, or people you have seen recently, perhaps the previous day or a week before.

The idea is that certain types of experiences take a week to become encoded into long-term memory, and some of the images from the consolidation process will appear in a dream. Events experienced while awake are said to feature in 1 to 2 percent of dream reports, although 65 percent of dream reports reflect aspects of recent waking life experiences.

The dream-lag effect has been reported in dreams that occur at the REM stage but not those that occur at stage 2. A study exploring different types of memory within dream content among 32 participants found the following:. Researchers suggest that memories of personal experiences are experienced fragmentarily and selectively during dreaming. The purpose may be to integrate these memories into the long-lasting autobiographical memory. A hypothesis stating that dreams reflect waking-life experiences is supported by studies investigating the dreams of psychiatric patients and patients with sleep disorders.

In short, their daytime symptoms and problems are reflected in their dreams. In , Freud described a category of dreams known as "biographical dreams. Many authors agree that some traumatic dreams perform a function of recovery. One paper hypothesizes that the main aspect of traumatic dreams is to communicate an experience that the dreamer has in the dream but does not understand.

This can help an individual reconstruct and come to terms with past trauma. The themes of dreams can be linked to the suppression of unwanted thoughts and, as a result, an increased occurrence of that suppressed thought in dreams. The results demonstrate that there were increased dreams about the unwanted thought and a tendency to have more distressing dreams. They also imply that thought suppression may lead to significantly increased mental disorder symptoms. Research has indicated that external stimuli presented during sleep can affect the emotional content of dreams.

For example, the positively-toned stimulus of roses in one study yielded more positively themed dreams, whereas the negative stimulus of rotten eggs was followed by more negatively themed dreams. Up to now, the frequencies of typical dream themes have been studied with questionnaires. These have indicated that a rank order of 55 typical dream themes has been stable over different sample populations.

For example, from to , there was an increase in the percentage of people who reported flying in dreams. This could reflect the increase in air travel. Some have hypothesized that one cluster of typical dreams, including being an object in danger, falling, or being chased, is related to interpersonal conflicts. Another cluster that includes flying, sexual experiences, finding money, and eating delicious food is associated with libidinal and sexual motivations. A third group, containing dreams that involve being nude, failing an examination, arriving too late, losing teeth, and being inappropriately dressed, is associated with social concerns and a fear of embarrassment.

This entry provides an overview of the main themes in the philosophical discussion on sleep and dreaming and emphasizes the connection between issues from different areas of philosophy. Because recent philosophical work on dreaming has taken on a distinctly interdisciplinary flavor, this entry also includes pointers to the relevant scientific literature and gives several examples of how evidence from scientific sleep and dream research has informed the philosophical debate, and vice versa.

The most famous and most widely discussed philosophical problem raised by dreaming is whether dreams pose a threat towards our knowledge of the external world see Williams ; Stroud ; Newman ; Klein Descartes illustrates the problem in a particularly compelling manner in the Meditations , where he uses the dream example to motivate skepticism about sensory-based beliefs about the external world, including his own bodily existence. Dreams are clearly not the only case in which sensory experience can lead us astray; familiar cases of sensory illusions show that perception is not always reliable.

Dreams and Dreaming (Stanford Encyclopedia of Philosophy)

Yet, as Descartes notes, these cases are too easily avoided to raise general doubts about the reliability of sensory perception. The same is not true, however, for dreaming. Dreams suggest that even in a best-case scenario of sensory perception Stroud , in which standard cases of misperception as in seeing very small or faraway objects as too big or too small can be ruled out and which consequently seem indubitably certain Descartes There are different ways of construing the dream argument. A particularly drastic claim would be that Descartes might conceivably be trapped in a lifelong dream in the sense that none of his experiences, including his waking experiences, have ever been caused by external objects Newman calls this the Always Dreaming Doubt.

A weaker claim is that while he is not always dreaming, he cannot rule out, at any given moment, that he is now dreaming the Now Dreaming Doubt ; for a fuller discussion of both versions, see Newman This weaker claim is still epistemologically damaging: His doubt thus prevents him from possessing sensory-based knowledge about the world. The general form of Cartesian-style skeptical arguments can be reconstructed as follows this standard reconstruction is quoted from Klein It is also important to see what the dream argument does not do. Even in dreams, the evidence of reason, or so Descartes would have it, is trustworthy.

Consequently, dreams do not undermine our ability to engage in the project of rational inquiry Frankfurt ; but see Broughton , and the possibility of dream deception is limited to sensory-based beliefs. Dream arguments have been a staple of philosophical skepticism since antiquity and in fact were so well known in the 17 th century that in his objections to the Meditations , Hobbes criticized Descartes for not having come up with a more original argument and boring the reader with the all-too-familiar scenario of dream deception.

Edited by Charles M. Morin and Colin A. Espie

By contrast, many who discussed the dream example before him did not take the epistemological threat posed by dreaming to be unique. In the Theaetetus e , Plato has Socrates discuss a defect in perception that is common to. By contrast, Descartes thought that dreams pose a more serious threat to sensory-based knowledge than avoidable cases of sensory illusions. He also thought that dreams leave our ability to engage in rational inquiry intact, thus setting them apart from insanity and delusions.

Dreams also appear in the canon of standard arguments or modes used by the Pyrrhonists to counter any knowledge claims, with the fourth of these arguments stating that the deliverances of the senses vary in different conditions such as health, illness, sleep, waking, joy or sorrow and hence are not to be trusted Diogenes Laertius, Lives of Eminent Philosophers; Sextus Empiricus, Outlines of Pyrrhonism. Augustine Against the Academics ; Confessions acknowledges the dream problem, but tries to contain it by arguing that even if we are deceived while dreaming, we can at least distinguish dreams and illusions from actual perception retrospectively see Matthew And Montaigne The Apology for Raymond Sebond , alluding to a variety of sensory illusions, notes that wakefulness itself is infested by reveries, which in some sense are a worse epistemological threat than nocturnal dreams.

On this view, dream deception is no longer set apart even from standard wake states, but rather is used in a metaphorical sense referring to any type of sensory deception. This has to do with the unique style of the Meditations. As Frankfurt points out, the first-person narrator of the Meditations is an everyman, whose epistemic situation is in no way idiosyncratic as would be the case if he were insane , but rather representative of the typical defects of any human mind.

The dream argument is a compelling example of this. Finally, much attention has been devoted to several dreams Descartes reportedly had as a young man and that according to his biographer Adrien Baillet embodied the theoretical doubts and the project of pure inquiry he later developed in the Discourse and Meditations see also Leibniz IV; Cole ; Keefer Prominent researchers such as Freud and Rechtschaffen personal communication, quoted in Cole The inherent appeal to empirical plausibility is also what sets Cartesian dream skepticism apart from alternative versions of external-world skepticism such as the evil genius hypothesis , the brain-in-a-vat thought experiment and Matrix -style scenarios of deception.

The first of these is introduced by Descartes in the First Meditation. After discussing the dream argument, Descartes introduces the possibility of an omnipotent but evil genius determined to deceive us even in our most basic beliefs. While he presents the scenario of dream deception as something that has often actually happened to him, he emphasizes that the evil genius hypothesis is a mere fiction intended to aid him in his systematic doubt Meditations , I.

Joseph De Koninck

Still, the evil genius hypothesis radicalizes the dream argument in two respects. Two, unlike the weaker reading of the dream argument introduced above, it involves a continuing rather than a temporary form of deception. The brain-in-a-vat thought experiment introduces a slightly modernized version of the evil genius hypothesis.

The basic idea is that you are nothing but a disembodied brain in a vat containing nutrient fluids and appropriately stimulated by evil scientists or a supercomputer, with the result that your conscious experience is exactly the same as it would be if you were an ordinary, embodied human being see Putnam for a vivid description and refutation of the brain-in-a-vat thought experiment based on content or semantic externalism; see Brueckner for discussion. A popular version is introduced in the Matrix -trilogy, which has its protagonists living their lives in an unrecognized computer simulation while in fact, they are lying in pods.

Unlike the classical brain-in-a-vat thought experiment, matrixers are essentially embodied brains in vats for a detailed discussion of how the Matrix relates to the other skeptical scenarios discussed here, see Chalmers What distinguishes all three scenarios from the dream argument is that while the former appeal to logical or even nomological possibility, dream deception is commonly regarded as a regularly recurring actuality cf.

Windt ; see, however, Bostrom for an argument intending to show that there are good reasons for thinking that we are actually, and not just hypothetically, living in a computer simulation. Yet, even purely hypothetical skeptical scenarios may enhance their psychological force by capitalizing upon the analogy with real-world dreams. This systematic ambiguity, according to Clark, is what makes the Matrix scenario so compelling.

At the end of the Sixth Meditation , Descartes himself suggests that this is not the case. Contrary to his remarks in the First Meditation , he notes that dreams are in fact quite different from waking experiences, for instance in that they are only rarely connected to waking memories and in that persons may suddenly appear or disappear in dreams.

Indeed, he uses this more sophisticated phenomenological description Frankfurt to introduce the famous coherence test of dreaming and wakefulness. Contrary to his earlier remarks in the First Meditation , he thinks he has now found a mark by which dreaming and wakefulness can be distinguished cf. 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.

And I ought not in the least degree to doubt of the truth of these presentations, if, after having called together all my senses, my memory, and my understanding for the purpose of examining them, no deliverance is given by any one of these faculties which is repugnant to that of any other: He concludes that dreaming is no longer a serious threat to sensory-based knowledge: Hobbes argues that if it is possible that someone could merely dream of successfully performing the coherence test, the test is useless. Indeed, the alleged incoherence of dreams is closely related to empirical work on dream bizarreness, which investigates the occurrence of discontinuities e.

Other authors have tried to use research findings to limit or even escape the threat of dream deception. Grundmann appeals to scientific dream research to introduce an introspective criterion by which we can determine that we are awake rather than dreaming. Because critical reasoning abilities are typically absent in dreams, he argues that when we introspectively notice that we are able to engage in critical reflection and when ongoing experience is seamlessly integrated with our memories, we have good reason to think that we are now awake.

However, Windt argues that reasoning is not uniformly absent in the dream state and is often systematically corrupted when it does occur. While genuinely rational thought at least sometimes occurs in dreams, it is not recognizable: Either way, an important point is that any version of the dream argument that appeals to real-world dreams, for instance by making implicit assumptions about what it is actually or even typically like to dream, is open to empirical investigation.

Dream research can thus be used, at least in principle, to assess the empirical plausibility of characterizations of dreaming in the context of different skeptical and anti-skeptical arguments. This raises the interesting possibility that any version of the dream argument that appeals to real-world dreams can at best justify a local form of skepticism, but cannot show, on pains of becoming self-defeating, that dreams pose a global threat to knowledge in general including knowledge about dreams; cf.

Stroud ; Grundmann Aside from concerns about empirical plausibility, it is important to note that Cartesian dream skepticism depends on even more basic background assumptions. In particular, it assumes that dreams are deceptive, first, because they are conscious experiences that are subjectively indistinguishable from standard waking experiences and second, because they involve false beliefs.

One strategy for refuting Cartesian dream skepticism in the newer literature has been to question these assumptions and deny either that dreams are experiences at all Malcolm , or that they are deceptive in the ways envisioned by Descartes. A common strategy is to allow that dreams are experiences but deny either that they involve false percepts or that they involve false sensory-based beliefs, or both Ichikawa ; see section 2.

For this reason, the epistemological problem of dream skepticism is both historically and systematically related to newer treatments of dreaming in philosophy of mind. Malcolm argues that attempts to conceive of dreams as experiences during sleep are senseless and that dreams consequently provide no foothold for philosophical skepticism. On this view, external-world skepticism motivated by dreaming can be refuted by defending internal-world skepticism about the experiential status of dreaming.

It follows that retrospective dream reports are the sole criterion for determining whether a dream occurred and that there is no independent way of verifying the occurrence of dreams in sleep. According to Malcolm, dream reports and waking memory reports are governed by different grammars and it would be mistaken to infer that an identity of experience lies behind them:. 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.

On this view, dream thoughts and feelings do not count as thoughts and feelings at all. For the same reason, it is impossible to mistakenly think, judge or assert that one is now awake while in fact one is dreaming Malcolm While Malcolm seems to be saying that conscious experience is conceptually tied to wakefulness, he later claims that speaking of dreams as conscious experiences is unintelligible:. If having experiences in sleep involves having thoughts, impressions, beliefs etc.

An important consequence of this view is that because dream reports, for Malcolm, are the sole criterion of dreaming, there can be no additional observational evidence for saying that a person is now asleep and dreaming. According to Malcolm, contemporaneous evidence such as sleepwalking or sleeptalking could not count as evidence for saying that dreams are experiences occurring during deep sleep, because they would show that the person in question was at least partially awake. Similarly, any attempts to adopt a physiological criterion of dreaming such as EEG measures of brain activity during sleep would change the concept of dreaming.

Hence, according to Malcolm, empirical evidence is irrelevant for the study of dreaming and attempts to study dreams scientifically are misconceived. It does not imply that nothing goes on in our minds while we dream. Of course Malcolm would think it did: If we do not, then there is no longer an obvious contradiction involved in saying that one has thoughts, feelings or beliefs—or perhaps even experiences—while asleep and dreaming. This should alert us to the fact that purely conceptual arguments of the type proposed by Malcolm do not, on their own, prohibit the application of such mental state terms to dreaming Windt To the extent that they do, this is a mere conceptual stipulation and not really informative for an interdisciplinary investigation of dreaming.

Rather, whether dream thoughts, feelings or beliefs are sufficiently similar to waking ones to count as real instances of their kind is an open question. What these have in common is that is that they are phenomenal states: Asking about dream experience, then, is to ask whether it is like something to dream while one is dreaming, and whether what it is like is similar to or relevantly different from corresponding waking experiences.

Note that these are two different questions: It might be like something to dream and dreams might be experiences in this very general sense , though what it is like to dream might still be different from standard waking experience. If so, dreams might count as experiences even if they do not involve actual instances of sensations, emotions etc.

A second important objection to the view that dreams are conscious experiences during sleep is the claim that it relies on insufficient empirical evidence or is even empirically implausible. A particularly prominent version of this objection is to say that dreams lack temporal extension: The cassette theory says that dreams are the product of two processes: Importantly, the only difference between the received view and the cassette theory is that the former additionally posits a conscious presentation process during sleep. On the received view, it is like something to dream; on the cassette theory, it is only like something to recall dreams.

Both theories, however, are supposed to deal equally well with the available empirical evidence, for instance on the relationship between dreaming and REM sleep. The important point, for Dennett, is that it is impossible to distinguish between the two rival theories on the basis of dream recall.

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In Consciousness Explained , Dennett uses a similar thought experiment to undermine the distinction between memory insertion and memory revision for waking memory reports see also Emmett for a critical discussion of this point. At this point, Maury awoke to find that the headboard of his bed had fallen on his neck. Because the dream seemed to systematically build up to its dramatic climax, which in turn was occasioned, it would seem, by an external stimulus, he and others suggested that such cases were best explained as instantaneous memory insertions experienced at the moment of awakening.

This theory, also known as the Goblot-hypothesis, was discussed by many dream researchers, such as Binz , Goblot , Freud , and more recently Hall ; for a discussion from the perspective of contemporary dream research, see Kramer It also continues to be discussed in the contemporary literature. Rosen argues that dreams are experiences, but at the same time proposes that Malcolm and Dennett were right to raise skeptical worries about the trustworthiness of dream reports. Her narrative fabrication thesis says that dream reports are in fact often the product of confabulation and fail to accurately describe experiences occurring during sleep.

By contrast, Windt defends an anti-skeptical view according to which dream reports can, at least under certain conditions, be regarded as trustworthy with respect to previous experience during sleep. Whereas Dennett takes the empirical evidence to be insufficient for deciding the question of whether dreams are experiences, more recent authors Flanagan ; Metzinger ; Revonsuo ; Rosen ; Windt suggest otherwise.

A first reason for thinking that dreams are experiences during sleep is the relationship between dreaming and REM rapid eye movement sleep. This latter activity is in fact indistinguishable, using EEG measures alone, from measures obtained during wakefulness. REM sleep is also characterized by rapid eye movements and a near-complete loss of muscle tone. Further characteristics of REM sleep include increased blood pressure, respiratory rate and pupil diameter as well as irregular heart rate for details, see Dement Because of this combination of wake-like brain activity and peripheral paralysis, REM sleep is sometimes also called paradoxical sleep Jouvet Importantly, reports of dreaming are much more frequent following REM sleep awakenings The former tend to be more elaborate, vivid, and emotionally intense, whereas the latter tend to be more thought-like, confused, non-progressive and repetitive Hobson et al.

Yet, attempts to identify dreaming with mental activity during REM sleep are controversial, and many now hold that dreams can occur in all stages of sleep e. The controversy about the sleep-stage correlates of dreaming is further complicated by the fact that there is currently no standardized and widely accepted definition of dreaming Pagel et al. It thus seems plausible that. A more differentiated picture of brain activity during sleep and its relation to dreaming is suggested by neuroimaging studies, which show that REM sleep is characterized by a shift in regional activation patterns compared to both wakefulness and NREM sleep Dang-Vu et al.

High activation levels in the pons, thalamus, temporo-occipital, motor, limbic, and paralimbic areas including the amygdala , equaling or even surpassing those seen in wakefulness, fit in well with the predominance of visual and motor imagery during dreams and with the frequency of intense, often negative emotions. The comparative deactivation of the dorsolateral prefrontal and inferior parietal cortices fits in well with the cognitive deficits often thought to characterize dreaming such as the loss of self-awareness, the absence of critical thinking, mnemonic deficits and the delusional belief in the reality of dream events Hobson et al.

This convergence of neuroscientific evidence and the phenomenology of dreaming thus suggests the outlines of a naturalistic theory of dreaming. And if we follow Dennett in thinking that this kind of evidence is relevant for determining whether dream sensations and emotions are real instances of their kind, then this is a compelling reason for saying that dreams are, after all, experiences, in the sense of involving the phenomenology of seeing, feeling, etc during sleep.

A second line of evidence comes from lucid dreams, or dreams in which one knows that one is dreaming and is often able to exercise some level of dream control LaBerge The term lucid dreaming was coined by van Eeden , but the phenomenon has been known for centuries. Aristotle On Dreams already notes that one can sometimes be aware, while dreaming, that one is dreaming.

Yet, many theorists, including many philosophers e. Researchers investigating lucid dreams in the laboratory, however, have proved otherwise Hearne ; LaBerge et al. They showed that lucid dreamers can use specific, pre-arranged patterns of eye movements e. Retrospective reports confirm that the dreamer really was lucid and signaled lucidity Dresler et al. This technique has been used to study muscular activity accompanying body movements in dreams Erlacher et al. Eye signals can also be used to measure the duration of different activities performed in lucid dreams—e.

Preliminary evidence suggests that walking and gymnastics take more time in lucid dreams than in wakefulness, but that the duration of counting is roughly the same. This is exactly the opposite of what would be predicted by the cassette theory, according to which the duration of dream actions should be much shorter than in wakefulness. A third line of evidence comes from dream-enactment behavior Nielsen et al. Due to a loss of the muscular atonia that accompanies REM sleep in healthy subjects, these patients show complex, seemingly goal-directed behaviors such as running or fighting off an attacker during REM sleep.

Retrospective dream reports often match the observed behaviors, suggesting that patients are literally acting out their dreams during sleep. The discovery of REM sleep also profoundly altered the theoretical conception of sleep. Going back to Aristotle On Sleeping and Waking , sleep had been defined in negative terms as the absence of wakefulness and perception. With the discovery of REM sleep, sleep came to be regarded as a heterogeneous phenomenon characterized by the cyclic alteration of different sleep stages.

The folk-psychological dichotomy between sleep and wakefulness now seemed oversimplified and empirically implausible. The changing view of sleep was accompanied by a changed understanding of dreaming. Where Aristotle On Dreams had still allocated dreaming to the residual movements of the sensory organs arising during the quiet of sleep and in the absence of external sensory stimulation, researchers from the 19 th century onwards believed dreams to occur in an intermediate period between sleep and wakefulness. Also, from the s onwards, the scientific study of dreams for the first time seemed feasible, and at least initially, the new fields of scientific sleep and dream research developed together.

It was in this climate that Malcolm , appealed to the earlier practice of regarding dream reports as the sole source of evidence for the study of dreaming and objected to the classification of dreams as experiences occurring in sleep. According to Malcolm, experiences could at best occur during half sleep, whereas he followed Aristotle in assuming that dreaming proper occurred during deep sleep. Seen in this light, Malcolm was as much objecting to the reconceptualization of dreams as to that of sleep for an excellent history of the study of sleep and dreaming, see Kroker Granting that dreams are experiences in the sense of phenomenal experience, as described above , how can the conscious experience of dreaming be described conceptually?

Throughout the history of philosophy, the standard view has been that dreams have the same phenomenal character as waking perception and count as hallucinations in the philosophical sense, that is, as experiences that are subjectively indistinguishable from genuine perception but where there is no mind-independent object being perceived Crane ; Macpherson As is the case for waking hallucinations, dreams seemingly put us in contact with mind-independent objects.

Yet, because dreams unfold in the absence of an appropriate contemporaneous stimulus sources, they fit the philosophical concept of hallucination. Even if I seem to see my bedroom in such a dream, and even if I my visual experience is exactly the same as it would be if I were to open my eyes, this would still not count as a case of sensory perception: In fact, this is why false awakening are sometimes thought to be a particularly compelling reason for endorsing dream skepticism cf. In the silence of sleep and in the absence of any contemporaneous sensory stimulation, these residual movements result in sometimes vivid sensory imagery that is subjectively indistinguishable from actual sensory perception.

Similar views of dreams as the after-effects of a prior stimulus were held by many other ancient authors Dreisbach ; Barbera The only difference between dreams and waking experiences, according to Berkeley, lies in the comparative instability and lack of coherence of dreams see Downing for details. In dreams, according to Russell,. 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.

Here, we see that historically, epistemological questions about dreaming were closely connected to psychological questions and questions from philosophy of mind about the nature and ontology of dream experience. On the one hand, Hume is committed to the empiricist claim that as mere creatures of the mind, dreams depend on prior impressions but themselves count as ideas. In the phenomenological tradition, dreams are often discussed in the context of theories of the imagination, if only to remark that phenomenologically, they are clearly distinct from waking imaginings and daydreams and should rather, as is the case for hallucinations and illusions, be classified as perceptions e.

Dreams are experienced as reality; in dreams as in wakefulness, but unlike in waking fantasy and daydreams, we feel, simply, present in a world Uslar ; Globus This claim is central to the virtual reality metaphor of dreaming , according to which consciousness itself is essentially dreamlike in that even in wakefulness, perceptual experience is a kind of online hallucination see also Metzinger , Again, the idea is that dreams are hallucinatory because dreaming feels exactly like perceiving, but unfolds independently of an appropriate external stimulus source, and because both feel different from imagining or daydreaming.

The description of dreams as hallucinations, virtual realities or world-analogues, popular both in the phenomenological tradition and in contemporary, empirically informed philosophical treatments of dreaming, is complemented by the scientific literature. Hobson , Hobson et al. However, attempts to analogize dreaming and waking experience may be premature.

He argues that improved methods of reporting dreams and specially trained subjects might be needed to make progress on this question Nielsen There is also some controversy in the psychological literature as to whether dreams should be regarded as hallucinations. By contrast, ffytche ; ffytche et al.

Saying that dreams are hallucinations is not, however, the only way of making sense of the claim that dreaming has the same phenomenal character as waking perception. An alternative is to say that at least certain kinds of dream imagery are illusory in the philosophical sense of an experience in which an external object is perceived as having different properties from the one it actually has cf. Smith ; Crane In the first stage we do not sleep very deeply and we wake up easily.

During the following stages our sleep gets deeper and deeper. During this phase our heart rate and breathing gets faster. Blood pressure goes up and the brain starts to work but the body does not. Most dreaming occurs in this phase. There can be up to seven such REM phases in one night. Dreaming is an activity of the brain. It produces electrical waves which can be measured with an electroencephalograph.

Dreams occur when brain waves are especially fast. If you think that you never dream, you are wrong. Most of the time we cannot remember our dreams. Theorists say that we dream mostly about the thoughts and wishes that we repress.

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