View source for Dream

{{Short description|Phenomenon of the mind while sleeping}}
{{Other uses|Dream (disambiguation)|Dreams (disambiguation)}}
{{pp-vandalism|small=yes}}
[[File:A dream (BM 1868,0808.9057).jpg|thumb|upright=1.5|In this illustration, politician [[Daniel O'Connell]] dreams of a confrontation between his outfit and that of [[George&nbsp;IV]] (r. 1820–30; shown via a [[thought bubble]])]]

A '''dream''' is a succession of [[image]]s, dynamic scenes and situations, [[idea]]s, [[emotions]], and [[sensation (psychology)|sensations]] that usually occur involuntarily in the [[mind]] during certain stages of [[sleep]].<ref>{{cite web |url=http://www.thefreedictionary.com/dream |title=Dream |publisher=The American Heritage Dictionary of the English Language, Fourth Edition. 2000 |access-date=7 May 2009}}</ref> Humans spend about two hours dreaming per night,<ref>{{cite web |year=2006 |title=Brain Basics: Understanding Sleep |url=http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm |access-date=16 December 2007 |publisher=[[National Institute of Neurological Disorders and Stroke]] |url-status=dead |archive-url=https://web.archive.org/web/20071011011207/http://www.ninds.nih.gov/disorders/brain_basics/understanding_sleep.htm |archive-date=11 October 2007}}</ref> and each dream lasts around 5–20 minutes, although the dreamer may [[Time perception|perceive the dream]] as being much longer.<ref name="HSWDream">{{cite book |year=2006 |title=How Dream Works |author=Lee Ann Obringer |url=http://science.howstuffworks.com/dream3.htm |access-date=4 May 2006 |url-status=live |archive-url=https://web.archive.org/web/20060418032147/http://science.howstuffworks.com/dream3.htm |archive-date=18 April 2006}}</ref>

The content and function of dreams have been topics of scientific, philosophical and religious interest throughout [[recorded history]]. [[Dream interpretation]], practiced by the [[Babylonia]]ns in the third millennium [[BCE]]<ref>{{cite book |last1=Krippner |first1=Stanley |last2=Bogzaran |first2=Fariba |last3=Carvalho |first3=Andre Percia de |date=2002 |title=Extraordinary Dreams and How To Work with Them |location=Albany, NY |publisher=State University of New York Press |quote=Clay tablets have been found, dating to about 2500 B.C.E., that contain interpretive material for Babylonian and [[Assyria]]n dreamers. |page=9 |isbn=0-7914-5257-3}}</ref> and even earlier by the ancient [[Sumer]]ians,<ref>{{cite book |last=Seligman |first=K |date=1948 |title=Magic, Supernaturalism and Religion |location=New York |publisher=Random House}}</ref><ref name="BlackGreen1992">{{cite book |last1=Black |first1=Jeremy |first2=Anthony |last2=Green |title=Gods, Demons and Symbols of Ancient Mesopotamia: An Illustrated Dictionary |location=Austin |publisher=University of Texas Press |year=1992 |isbn=0714117056 |pages=71–72, 89–90}}</ref> figures prominently in religious texts in several traditions, and has played a lead role in psychotherapy.<ref name="Freud1">{{cite book |last=Freud |first=Sigmund |translator=James Strachey |editor=James Strachey |author-link=Sigmund Freud |date=1965 |title=The Interpretation of Dreams |location=New York |publisher=Avon}}</ref><ref>{{cite journal |last1=Schredl |first1=Michael |last2=Bohusch |first2=Claudia |last3=Kahl |first3=Johanna |last4=Mader |first4=Andrea |last5=Somesan |first5=Alexandra |title=The Use of Dreams in Psychotherapy |journal=The Journal of Psychotherapy Practice and Research |year=2000 |volume=9 |issue=2 |pages=81–87}}</ref> [[Dreamwork]] is similar, but does not seek to conclude with definite meaning. The scientific study of dreams is called [[oneirology]].<ref>{{cite journal |last=Kavanau |first=J.L. |title=Sleep, memory maintenance, and mental disorders |journal=Journal of Neuropsychiatry and Clinical Neurosciences |year=2000 |volume=12 |issue=2 |pages=199–208 |doi=10.1176/jnp.12.2.199 |pmid=11001598 |issn = 0895-0172 }}</ref> Most modern dream study focuses on the neurophysiology of dreams and on proposing and testing hypotheses regarding dream function. It is not known where in the brain dreams originate, if there is a single origin for dreams or if multiple regions of the brain are involved, or what the purpose of dreaming is for the body (or brain or mind).

The human dream experience and what to make of it has undergone sizable shifts over the course of history.<ref name="Dodds1">{{cite book |last= Dodds |first=E. R. |author-link=E. R. Dodds |date=1951 |title=The Greeks and the Irrational |location=Berkeley |publisher=University of California Press |quote=The Greeks never spoke as we do of ''having'' a dream, but always of ''seeing'' a dream.... |page= 105}}</ref><ref name="Packer1">{{cite book |last=Packer |first=Sharon |date=2002 |title=Dreams in Myth, Medicine, and Movies |location=Westport, CT |publisher=Praeger Publishers |quote=…[M]any more ancient cultures think that dreams are imposed by a force that resides outside the individual. |page=85 |isbn=0-275-97243-7}}</ref> Long ago, according to writings from [[Mesopotamia]] and [[Ancient Egypt]], dreams dictated post-dream behaviors to an extent that was sharply reduced in later millennia.{{clarify|date=August 2023}} These ancient writings about dreams highlight visitation dreams, where a dream figure, usually a deity or a prominent forebear, commands the dreamer to take specific actions, and which may predict future events.<ref>{{cite book |last=Macrobius |author-link=Macrobius |translator=[[William Harris Stahl|W. H. Stahl]] |date=1952 |orig-date=430 |title=Commentary on the Dream of Scipio |location=New York |publisher=Columbia University Press |quote=We call a dream oracular in which a parent, or a pious or revered man, or a priest, or even a god clearly reveals what will or will not transpire, and what action to take or to avoid. |page=90}}</ref><ref>Dodds (1951), referring to the type of dream described by Macrobius: "This last type is not, I think, at all common in our own dream-experience. But there is considerable evidence that dreams of this sort were familiar in antiquity." (p. 107).</ref><ref name=Krippner1>{{cite book |last1=Krippner |first1=Stanley |last2=Bogzaran |first2=Fariba |last3=Carvalho |first3=André Percia de |date=2002 |title=Extraordinary Dreams and How To Work with Them |location=Albany |publisher=State University of New York Press |quote=The Egyptian papyrus of Deral-Madineh was written about 1300 B.C.E. and gives instructions on how to obtain a dream message from a god. |page=10 |isbn=0-7914-5257-3}}</ref> Framing the dream experience varies across cultures as well as through time.

Dreaming and sleep are intertwined. Dreams occur mainly in the [[Rapid eye movement sleep|rapid-eye movement (REM) stage of sleep]]—when [[brain activity]] is high and resembles that of being awake. Because REM sleep is detectable in many species, and because research suggests that all mammals experience REM,<ref>{{cite journal |last1=Lesku |first1=J. A. |last2=Meyer |first2=L. C. R. |last3=Fuller |first3=A. |last4=Maloney |first4=S. K. |last5=Dell'Omo |first5=G. |last6=Vyssotski |first6=A. L. |last7=Rattenborg |first7=N. C. |year=2011 |title=Ostriches sleep like platypuses |journal=PLOS ONE |volume=6 |issue=8 |pages=1–7 |doi=10.1371/journal.pone.0023203 |pmid=21887239 |pmc=3160860 |bibcode= 2011PLoSO...623203L |doi-access=free}}</ref> linking dreams to REM sleep has led to conjectures that animals dream. However, humans dream during non-REM sleep, also, and not all REM awakenings elicit dream reports.<ref name=Solms1>{{cite journal |last=Solms |first=Mark |author-link=Mark Solms |title=Dreaming and REM sleep are controlled by different brain mechanisms |journal=Behavioral and Brain Sciences |year=2000 |volume=23 |issue=6 |pages=843–850 |doi=10.1017/S0140525X00003988 |pmid=11515144 |s2cid=7264870 |quote=Dreaming and REM sleep are incompletely correlated. Between 5 and 30% of REM awakenings do not elicit dream reports; and at least 5–10% of NREM awakenings do elicit dream reports that are indistinguishable from REM....}}</ref> To be studied, a dream must first be reduced to a verbal report, which is an account of the subject's memory of the dream, not the subject's dream experience itself. Therefore, dreaming by non-humans is currently unprovable, as is dreaming by human fetuses and pre-verbal infants.<ref>{{cite book |last=Bulkeley |first=Kelly |title=Dreaming in the world's religions: A comparative history |year=2008 |isbn=978-0-8147-9956-7 |page=14 |publisher=NYU Press |quote=Do animals dream? We currently have no means of proving it one way or the other, just as we have no way to determine whether human fetuses and newborns are genuinely dreaming before they develop the ability to speak and relate their experiences.}}</ref>

== Etymology ==
In [[Old English]], the word ''drēam'' was used to describe "noise", "joy", or "music", but not related to the sleep-induced brain activity. It was only in the 13th century that the word ''dream'' was used to describe "a series of thoughts, images or emotions occurring during sleep". Etymologists believe that this change was influenced due to the [[Old Norse]] ''draumr'', which had the same meaning as the word ''dream'' nowadays.<ref>{{cite web |title=An Analysis of 'Dream' |url=https://www.merriam-webster.com/wordplay/word-history-of-dream |website=merriam-webster.com |publisher=Merriam-Webster |access-date=20 June 2025|archive-url=https://web.archive.org/web/20240913062137/https://www.merriam-webster.com/wordplay/word-history-of-dream|archive-date=13 September 2024|url-status=live}}</ref>

== Subjective experience and content ==
{{Further|Oneiromancy}}
[[File:Raja Ravi Varma, Usha's Dream (oleographic print).jpg|left|thumb|''Usha Dreaming Aniruddha'' (oleographic print) [[Raja Ravi Varma]] (1848–1906)]]

Preserved writings from early Mediterranean civilizations indicate a relatively abrupt change in subjective dream experience between [[Bronze Age]] antiquity and the beginnings of the [[classical antiquity|classical era]].<ref>{{cite book |last=Damasio |first=Antonio |author-link= Antonio Damasio |date=2010 |title=Self Comes to Mind |location=New York |publisher=Pantheon Books |quote=…I sympathize with Julian Jaynes's claim that something of great import may have happened to the human mind during the relatively brief interval of time between the events narrated in the ''Iliad'' and those that make up the ''Odyssey''. |page=289 |isbn=978-0-307-37875-0}}</ref>

In visitation dreams reported in ancient writings, dreamers were largely passive in their dreams, and visual content served primarily to frame authoritative auditory messaging.<ref>{{Citation |last=Nielsen |first=Tore A. |contribution=Reality Dreams and Their Effects on Spiritual Belief: A Revision of Animism Theory |editor-last1=Gackenbach |editor-first1=Jayne |editor-last2=Sheikh |editor-first2=Anees A. |title=Dream Images: A Call to Mental Arms |year=1991 |pages=233–264 |place=Amityville, NY |publisher=Baywood |isbn=0-89503-056-X}}</ref><ref name="Dodds1"/><ref>{{cite journal|last=Atwan |first=Robert |title=The Interpretation of Dreams, The Origin of Consciousness, and the Birth of Tragedy |journal=Research Communication in Psychology, Psychiatry and Behavior |year=1981 |volume=6 |issue=2 |pages=163–182}}</ref> [[Gudea]], the king of the Sumerian city-state of [[Lagash]] (reigned {{circa}} 2144–2124 BCE), rebuilt the temple of [[Ningirsu]] as the result of a dream in which he was told to do so.<ref name="BlackGreen1992"/> After antiquity, the passive hearing of visitation dreams essentially gave way to visualized narratives in which the dreamer becomes a character who actively participates.

From the 1940s to 1985, [[Calvin S. Hall]] collected more than 50,000 dream reports at [[Western Reserve University]]. In 1966, Hall and Robert Van de Castle published ''The Content Analysis of Dreams'', outlining a coding system to study 1,000 dream reports from college students.<ref name="hallcontent">Hall, C., & Van de Castle, R. (1966). The Content Analysis of Dreams. New York: Appleton-Century-Crofts. [http://psych.ucsc.edu/dreams/Info/content_analysis.html Content Analysis Explained] {{webarchive |url=https://web.archive.org/web/20070412100915/http://psych.ucsc.edu/dreams/Info/content_analysis.html |date=12 April 2007}}</ref> Results indicated that participants from varying parts of the world demonstrated similarity in their dream content. The only residue of antiquity's authoritative dream figure in the Hall and Van de Castle listing of dream characters is the inclusion of God in the category of prominent persons.<ref>{{cite web |url=https://dreams.ucsc.edu/Coding/characters.html |title=The Classification and Coding of Characters |last1=Schneider |first1=Adam |last2=Domhoff |first2=G. William |publisher=University of California at Santa Cruz |access-date=17 July 2021}}</ref> Hall's complete dream reports were made publicly available in the mid-1990s by his protégé [[William Domhoff]]. More recent studies of dream reports, while providing more detail, continue to cite the Hall study favorably.<ref>{{cite journal |last1=Schredl |first1=Michael |last2=Ciric |first2=Petra |last3=Götz |first3=Simon |last4=Wittmann |first4=Lutz |date=November 2004 |title=Typical Dreams: Stability and Gender Differences |journal=The Journal of Psychology |volume=138 |issue=6 |doi=10.3200/JRLP.138.6.485-494 |pmid=15612605 |pages=485–494 |s2cid=13554573}}</ref>

[[File:Dream of Polish volunteers in French army 1914.JPG|thumb|upright|A soldier dreams: the trenches of WWI. [[Jan Styka]] (1858–1925).]]

In the Hall study, the most common emotion experienced in dreams was [[anxiety]]. Other emotions included [[Abandonment (emotional)|abandonment]], [[anger]], [[fear]], [[joy]], and [[happiness]]. [[Negative emotion]]s were much more common than positive ones.<ref name="hallcontent"/> The Hall data analysis showed that sexual dreams occur no more than 10% of the time and are more prevalent in young to mid-teens.<ref name="hallcontent"/> Another study showed that 8% of both men's and women's dreams have sexual content.<ref>Zadra, A., [http://www.journalsleep.org/PDF/AbstractBook2007.pdf "1093: Sex dreams: what do men and women dream about?"] {{webarchive |url=https://web.archive.org/web/20070927222607/http://www.journalsleep.org/PDF/AbstractBook2007.pdf |date=27 September 2007}}, ''Sleep'' Volume 30, Abstract Supplement, 2007 A376.</ref> In some cases, sexual dreams may result in [[orgasm]]s or [[nocturnal emission]]s. These are colloquially known as "wet dreams".<ref>{{cite web |url=http://www.measuredhs.com/pubs/pdf/FR157/04Chapter04.pdf |title=Badan Pusat Statistik "Indonesia Young Adult Reproductive Health Survey 2002–2004" p. 27 |access-date=4 April 2013 |url-status=live |archive-url=https://web.archive.org/web/20121209171035/http://measuredhs.com/pubs/pdf/FR157/04Chapter04.pdf |archive-date=9 December 2012}}</ref>

The visual nature of dreams is generally highly phantasmagoric; that is, different locations and objects continuously blend into each other. The visuals (including locations, people, and objects) are generally reflective of a person's memories and experiences, but conversation can take on highly exaggerated and bizarre forms. Some dreams may even tell elaborate stories wherein the dreamer enters entirely new, complex worlds and awakes with ideas, thoughts, and feelings never experienced before the dream.

People who are blind from birth do not have visual dreams. Their dream contents are related to other senses, such as [[hearing]], [[Somatosensory system|touch]], [[Olfaction|smell]], and [[taste]], whichever are present since birth.<ref>{{cite news |title=How do blind people dream? – The Body Odd |url=http://bodyodd.nbcnews.com/_news/2012/03/09/10602730-how-do-blind-people-dream?lite |date=March 2012 |access-date=10 May 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130124114342/http://bodyodd.nbcnews.com/_news/2012/03/09/10602730-how-do-blind-people-dream?lite |archive-date=24 January 2013}}</ref>

=== Effects of regional or global catastrophes === 
The [[COVID-19 pandemic]] also influenced the content of people's dreams, according to a scientific study of over 15,000 dream reports by [[Deirdre Barrett]]. This analysis revealed that themes involving fear, illness, and death were two to four times more prevalent in dreams following the onset of the pandemic than they were before.<ref>{{cite web | last=Heidt | first=Amanda | title=Why Are Recurring Dreams Usually Bad Ones? | website=Scientific American | date=2025-01-14 | url=https://www.scientificamerican.com/article/why-are-recurring-dreams-usually-nightmares/ | access-date=2025-01-15}}</ref>

== Neurophysiology ==
{{Main|Cognitive neuroscience of dreams}}
{{Further|Neuroscience of sleep}}

Dream study is popular with scientists exploring the [[mind–body problem|mind–brain problem]]. Some "propose to reduce aspects of dream phenomenology to neurobiology."<ref>{{cite journal |last1=Hobson |first1=J. Allan |last2=Pace-Schott |first2=Edward F. |last3=Stickgold |first3=Robert |author-link1=Allan Hobson |title=Dream science 2000: A response to commentaries on ''Dreaming and the Brain'' |journal=Behavioral and Brain Sciences |year=2000 |volume=23 |issue=6 |page=1019 |doi=10.1017/S0140525X00954025 |s2cid=144729368}}</ref> But current science cannot specify dream physiology in detail. Protocols in most nations restrict human brain research to non-invasive procedures. In the United States, invasive brain procedures with a human subject are allowed only when these are deemed necessary in surgical treatment to address medical needs of the same human subject.<ref>{{cite journal |last1=Chiong |first1=Winston |last2=Leonard |first2=Matthew K. |last3=Chang |first3=Edward F. |title=Neurosurgical Patients as Human Research Subjects: Ethical Considerations in Intracranial Electrophysiology Research |journal=Neurosurgery |year=2018 |volume=83 |issue=1 |pages=29–37 |doi=10.1093/neuros/nyx361 |pmid=28973530 |url=https://academic.oup.com/neurosurgery/article-abstract/83/1/29/3988112 |pmc=5777911}}</ref> Non-invasive measures of brain activity like [[electroencephalogram]] (EEG) voltage averaging or [[functional magnetic resonance imaging|cerebral blood flow]] cannot identify small but influential neuronal populations.<ref name="hob">Hobson, J. A., Pace-Schott, E. F., & Stickgold, R. (2000). "Dreaming and the brain: Toward a cognitive neuroscience of conscious states". ''Behavioral and Brain Sciences'', 23(6), 793–842.</ref> Also, [[functional magnetic resonance imaging|fMRI]] signals are too slow to explain how brains compute in real time.<ref>{{cite web |url=https://speakingofresearch.com/2009/07/31/the-limits-of-fmri/ |title=The limits of fMRI |last=Ringach |first=Dario L. |date=30 July 2009 |publisher=Speaking of Research |access-date=18 July 2021}}</ref>

Scientists researching some brain functions can work around current restrictions by examining animal subjects. As stated by the [[Society for Neuroscience]], "Because no adequate alternatives exist, much of this research must ''[sic]'' be done on animal subjects."<ref>{{cite web |url=https://www.sfn.org/Advocacy/Policy-Positions/Policies-on-the-Use-of-Animals-and-Humans-in-Research |title=Policies on the Use of Animals and Humans in Research |publisher=Society for Neuroscience |access-date=18 July 2021}}</ref> However, since animal dreaming can be only inferred, not confirmed, animal studies yield no hard facts to illuminate the neurophysiology of dreams. Examining human subjects with brain lesions can provide clues, but the lesion method cannot discriminate between the effects of destruction and disconnection and cannot target specific neuronal groups in heterogeneous regions like the brain stem.<ref name="hob"/>

== Generation ==
[[File:Antonio de Pereda - El sueño del caballero - Google Art Project.jpg|left|thumb|''[[The Gentleman's Dream|The Knight's Dream]]'', 1655, by [[Antonio de Pereda]]]]

Denied precision tools and obliged to depend on imaging, much dream research has succumbed to the [[law of the instrument]]. Studies detect an increase of blood flow in a specific brain region and then credit that region with a role in generating dreams. But pooling study results has led to the newer conclusion that dreaming involves large numbers of regions and pathways, which likely are different for different dream events.<ref>{{cite book |last=Uttal |first=William R. |author-link=William Uttal |title=Reliability in Cognitive Neuroscience |date=2013 |location=Cambridge, MA |publisher=The MIT Press|quote=Similarly, modern neuroscience research is increasingly showing that activation areas on the brain associated with a cognitive process are far more widely distributed than had been thought only a decade or so ago. Indeed, it now seems likely that most of the brain is active in almost any cognitive process. |page=4}}</ref>

Image creation in the brain involves significant neural activity downstream from eye intake, and it is theorized that "the visual imagery of dreams is produced by activation during sleep of the same structures that generate complex visual imagery in waking perception."<ref>{{cite journal |last=Solms |first=Mark |author-link=Mark Solms |title=Dreaming and REM sleep are controlled by different brain mechanisms |journal=Behavioral and Brain Sciences |year=2000 |volume=23 |issue=6 |pages=843–850; discussion 904–1121 |doi=10.1017/S0140525X00003988 |pmid=11515144 |s2cid=7264870}}</ref>

Dreams present a running narrative rather than exclusively visual imagery. Following their work with [[split-brain]] subjects, [[Michael Gazzaniga|Gazzaniga]] and [[Joseph E. LeDoux|LeDoux]] postulated, without attempting to specify the neural mechanisms, a "[[left-brain interpreter]]" that seeks to create a plausible narrative from whatever electro-chemical signals reach the brain's left hemisphere. Sleep research has determined that some brain regions fully active during waking are, during REM sleep, activated only in a partial or fragmentary way.<ref>{{cite journal |last1=Braun |first1=A. R. |last2=Balkin |first2=T. J |last3=Wesensten |first3=N. J. |last4=Carson |first4=R. E. |last5=Varga |first5=M. |last6=Baldwin |first6=P. |last7=Selbie |first7=S. |last8=Belenky |first8=G. |last9=Herscovitch |first9=P. |year=1997 |title=Regional cerebral blood flow through the sleep-wake cycle |journal=Brain |volume=120 |publisher=Oxford University Press |pages=1173–1197 |doi=10.1093/brain/120.7.1173 |pmid=9236630 |doi-access=free}}</ref> Drawing on this knowledge, textbook author James W. Kalat explains, "[A] dream represents the brain's effort to make sense of sparse and distorted information.... The cortex combines this haphazard input with whatever other activity was already occurring and does its best to synthesize a story that makes sense of the information."<ref>{{cite book |last=Kalat |first=James W. |date=2015 |title=Biological Psychology |edition=12th |location=Boston |publisher=Cengage |page=288 |isbn=978-1305105409}}</ref> Neuroscientist [[Indre Viskontas]] is even more blunt, calling often bizarre dream content "just the result of your interpreter trying to create a story out of random neural signaling."<ref>{{cite book |last=Viskontas |first=Indre |date=2017 |title=Brain Myths Exploded: Lessons from Neuroscience |location=Chantilly, VA |publisher=The Teaching Company |page=393}}</ref>

== Theories on function ==
{{Main|Oneirology}}
{{Further|Rapid eye movement sleep}}

For many humans across multiple eras and cultures, dreams are believed to have functioned as revealers of truths sourced during sleep from gods or other external entities.<ref>{{Cite book |last=Ribeiro |first=Sidarta |title=The oracle of night : the history and science of dreams |date=2021 |others=Daniel Hahn, Sidarta Translation of: Ribeiro |isbn=978-1-5247-4690-2 |edition= |location=New York |oclc=1200037413}}</ref> Ancient Egyptians believed that dreams were the best way to receive divine revelation, and thus they would induce (or "incubate") dreams. They went to sanctuaries and slept on special "dream beds" in hope of receiving advice, comfort, or healing from the gods.<ref name="Krippner1"/> From a Darwinian perspective dreams would have to fulfill some kind of biological requirement, provide some benefit for natural selection to take place, or at least have no negative impact on fitness. Robert (1886),<ref>Robert, W. Der Traum als Naturnothwendigkeit erklärt. Zweite Auflage, Hamburg: Seippel, 1886.</ref> a physician from Hamburg, was the first who suggested that dreams are a need and that they have the function to erase (a) sensory impressions that were not fully worked up, and (b) ideas that were not fully developed during the day. In dreams, incomplete material is either removed (suppressed) or deepened and included into memory. [[Sigmund Freud|Freud]], whose dream studies focused on interpreting dreams, not explaining how or why humans dream, disputed Robert's hypothesis<ref>{{cite book |last=Freud |first=Sigmund |translator=James Strachey |editor=James Strachey |author-link=Sigmund Freud |date=1965 |title=The Interpretation of Dreams |page=188 |location=New York |publisher=Avon |quote=The view adopted by Robert [1886, 9 f.] that the purpose of dreams is to unburden our memory of the useless impressions of daytime [cf. pp. 105 f.] is plainly no longer tenable....}}</ref> and proposed that dreams preserve sleep by representing as fulfilled those wishes that otherwise would awaken the dreamer.<ref>Rycroft, Charles. ''A Critical Dictionary of Psychoanalysis''. London: Penguin Books, 1995, p. 41.</ref> Freud wrote that dreams "serve the purpose of prolonging sleep instead of waking up. ''Dreams are the'' GUARDIANS ''of sleep and not its disturbers.''"<ref>{{cite book |last=Freud |first=Sigmund |translator=James Strachey |editor=James Strachey |author-link=Sigmund Freud |date=1965 |title=The Interpretation of Dreams |page=253 |location=New York |publisher=Avon}}</ref>

[[File:Taras Shevchenko painting 0019.jpg|thumb|left|''Grandmother and Granddaughter Dream'' (1839 or 1840). [[Taras Shevchenko]]]]

A turning point in theorizing about dream function came in 1953, when [[Science (journal)|''Science'']] published the [[Eugene Aserinsky|Aserinsky]] and [[Nathaniel Kleitman|Kleitman]] paper<ref>{{cite journal |last1=Aserinsky |first1=Eugene |last2=Kleitman |first2=Nathaniel |author-link=Eugene Aserinsky |title=Regularly Occurring Periods of Eye Motility, and Concomitant Phenomena, during Sleep |journal=Science |year=1953 |volume=118 |issue=3062 |pages=273–274 |doi=10.1126/science.118.3062.273 |pmid=13089671 |bibcode=1953Sci...118..273A}}</ref> establishing [[Rapid eye movement sleep|REM sleep]] as a distinct phase of sleep and linking dreams to REM sleep.<ref>{{Citation |last=Smith |first=Robert C. |contribution=The Meaning of Dreams: A Current Warning Theory |editor-last1=Gackenbach |editor-first1=Jayne |editor-last2=Sheikh |editor-first2=Anees A. |title=Dream Images: A Call to Mental Arms |year=1991 |pages=127–146 |place=Amityville, NY |publisher=Baywood |isbn=0-89503-056-X}}</ref> Until and even after publication of the Solms 2000 paper that certified the separability of REM sleep and dream phenomena,<ref name="Solms1"/> many studies purporting to uncover the function of dreams have in fact been studying not dreams but measurable REM sleep.

Theories of dream function since the identification of REM sleep include:

[[Allan Hobson|Hobson's]] and [[Robert McCarley|McCarley's]] 1977 [[activation-synthesis hypothesis]], which proposed "a functional role for dreaming sleep in promoting some aspect of the learning process...."<ref>{{cite journal |last1=Hobson |first1=J. Allan |last2=McCarley |first2=Robert W. |title=The Brain as a Dream State Generator: An Activation-Synthesis Hypothesis of the Dream Process |journal=The American Journal of Psychiatry |date=December 1977 |volume=134 |issue=12 |pages=1335–1348 |doi=10.1176/ajp.134.12.1335 |pmid=21570 |quote=The dream process is thus seen as having its origin in sensorimotor systems, with little or no primary ideational, volitional, or emotional content. This concept is markedly different from that of the "dream thoughts" or wishes seen by Freud as the primary stimulus for the dream.}}</ref> In 2010 a Harvard study was published showing experimental evidence that dreams were correlated with improved learning.<ref>{{cite web |last1=Benjamin |first1=Victoria |title=Study Links Dreaming to Increased Memory Performance |url=https://www.thecrimson.com/article/2010/4/27/maze-wamsley-group-navigating/#:~:text=A%20recent%20study%20published%20last,nap%2C%20according%20to%20Erin%20J. |website=The Harvard Crimson |access-date=27 January 2022}}</ref>

[[Francis Crick|Crick's]] and Mitchison's 1983 "[[reverse learning]]" theory, which states that dreams are like the cleaning-up operations of computers when they are offline, removing (suppressing) parasitic nodes and other "junk" from the mind during sleep.<ref>{{cite journal |last1=Evans |first1=C. |last2=Newman |first2=E. |year=1964 |title=Dreaming: An analogy from computers |journal=New Scientist |volume=419 |pages=577–579}}</ref><ref>{{cite journal |doi=10.1038/304111a0 |last1=Crick |first1=F. |last2=Mitchison |first2=G. |year=1983 |title=The function of dream sleep |journal=Nature |volume=304 |issue=5922 |pages=111–114 |pmid=6866101 |bibcode=1983Natur.304..111C |s2cid=41500914}}</ref>

[[Ernest Hartmann|Hartmann's]] 1995 proposal that dreams serve a "quasi-therapeutic" function, enabling the dreamer to process trauma in a safe place.<ref>{{cite journal |last=Hartmann |first=Ernest |title=Making Connections in a Safe Place: Is Dreaming Psychotherapy? |journal=Dreaming |year=1995 |volume=5 |issue=4 |pages=213–228 |doi=10.1037/h0094437}}</ref>

[[Antti Revonsuo|Revonsuo's]] 2000 threat simulation hypothesis, whose premise is that during much of human evolution, physical and interpersonal threats were serious, giving reproductive advantage to those who survived them. Dreaming aided survival by replicating these threats and providing the dreamer with practice in dealing with them.<ref>{{cite journal |last=Revonsuo |first=A. |title=The reinterpretation of dreams: an evolutionary hypothesis of the function of dreaming |journal=Behavioral and Brain Sciences |year=2000 |volume=23 |issue=6 |pmid=11515147 |doi=10.1017/S0140525X00004015 |pages=877–901 |s2cid=145340071}}</ref> In 2015, Revonsuo proposed social simulation theory, which describes dreams as a simulation for training social  skills  and  bonds.<ref>{{Cite journal |last1=Revonsuo |first1=A. |last2=Tuominen |first2=J. |year=2015 |title=Avatars in the Machine: Dreaming as a Simulation of Social Reality |journal=Open MIND |pages=1–28 |doi=10.15502/9783958570375|isbn=9783958570375 }}</ref>

[[David Eagleman|Eagleman's]] and [[Don Vaughn|Vaughn's]] 2021 defensive activation theory, which says that, given the brain's [[neuroplasticity]], dreams evolved as a visual hallucinatory activity during sleep's extended periods of darkness, busying the occipital lobe and thereby protecting it from possible appropriation by other, non-vision, sense operations.<ref>{{cite journal |last1=Eagleman |first1=David M. |last2=Vaughn |first2=Don A. |title=The Defensive Activation Theory: REM Sleep as a Mechanism to Prevent Takeover of the Visual Cortex |journal=Frontiers in Neuroscience |date=May 2021 |volume=15 |article-number=632853 |doi=10.3389/fnins.2021.632853 |pmid=34093109 |pmc=8176926 |doi-access=free}}</ref>

[[Erik Hoel]] proposes, based on artificial neural networks, that dreams prevent overfitting to past experiences; that is, they enable the dreamer to learn from novel situations.<ref>{{cite news |title=Weird dreams train us for the unexpected, says new theory |url=https://www.theguardian.com/science/2021/may/14/weird-dreams-train-us-for-the-unexpected-says-new-theory |access-date=5 January 2023 |work=the Guardian |date=14 May 2021 |language=en}}</ref><ref>{{cite journal |last1=Hoel |first1=Erik |title=The overfitted brain: Dreams evolved to assist generalization |journal=Patterns |date=14 May 2021 |volume=2 |issue=5 |article-number=100244 |doi=10.1016/j.patter.2021.100244 |pmid=34036289 |pmc=8134940 |language=en |issn=2666-3899|doi-access=free }}</ref>

== Religious and other cultural contexts ==
Dreams figure prominently in major world religions. The dream experience for early humans, according to one interpretation, gave rise to the notion of a human "[[Soul#Religious views|soul]]",<ref>{{cite book |last=Lévy-Bruhl |first=Lucien |author-link=Lucien Lévy-Bruhl |date=1923 |title=Primitive Mentality |translator=Lilian A. Clare |chapter=Chapter III Dreams |chapter-url=https://archive.org/details/primitivementali00levy_0/page/98/mode/2up?ref=ol&view=theater |location=New York |publisher=Macmillan |page=98 |quote=...[I]n dreams,...man passes from the one world to the other without being aware of it. Such is in fact the ordinary idea of the dream to primitive peoples. The "soul" leaves its tenement for the time being. It frequently goes very far away; it communes with spirits or with ghosts. At the moment of awakening it returns to take its place in the body once more.}}</ref> a central element in much religious thought. [[J. W. Dunne]] wrote: <blockquote>But there can be no reasonable doubt that the idea of a soul must have first arisen in the mind of primitive man as a result of observation of his dreams. Ignorant as he was, he could have come to no other conclusion but that, in dreams, he left his sleeping body in one universe and went wandering off into another. It is considered that, but for that savage, the idea of such a thing as a 'soul' would never have even occurred to mankind....<ref>{{cite book |last=Dunne |first=J. W. |date=1950 |orig-date=1927 |title=An Experiment with Time |location=London |publisher=Faber |page=23}}</ref></blockquote>

=== Hindu ===
In the [[Mandukya Upanishad]], part of the [[Veda]] scriptures of [[Hinduism|Indian Hinduism]], a dream is one of three states that the soul experiences during its lifetime, the other two states being the waking state and the sleep state.<ref>{{cite web |url=http://www.swami-krishnananda.org/mand/mand_4.html |title=The Mandukya Upanishad, Section 4 |last=Krishnananda |first=Swami |date=16 November 1996 |access-date=26 March 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150409004128/http://www.swami-krishnananda.org/mand/mand_4.html |archive-date=9 April 2015}}</ref> The earliest [[Upanishads]], written before 300 BCE, emphasize two meanings of dreams. The first says that dreams are merely expressions of inner desires. The second is the belief of the soul leaving the body and being guided until awakened.

=== Abrahamic ===
[[File:Michael Lukas Leopold Willmann 001.jpg|thumb|Jacob's dream of a [[Jacob's Ladder|ladder of angels]], c. 1690. [[Michael Willmann]]]]

In Judaism, dreams are considered part of the experience of the world that can be interpreted and from which lessons can be garnered. It is discussed in the Talmud, Tractate Berachot 55–60.

The ancient [[Hebrews]] connected their dreams heavily with their religion, though the Hebrews were [[monotheistic]] and believed that dreams were the voice of one God alone. Hebrews also differentiated between good dreams (from God) and bad dreams (from evil spirits). The Hebrews, like many other ancient cultures, incubated dreams in order to receive a divine revelation. For example, the Hebrew prophet [[Samuel]] would "lie down and sleep in the temple at [[Shiloh (biblical city)|Shiloh]] before the Ark and receive the word of the Lord", and [[Joseph (Genesis)|Joseph]] interpreted a Pharaoh's dream of seven lean cows swallowing seven fat cows as meaning the subsequent seven years would be bountiful, followed by seven years of famine. Most of the dreams in the [[Bible]] are in the [[Book of Genesis]].<ref>{{cite book |url={{Google books |id=zs3gup4iFu4C |page=15 |plainurl=yes}} |title=A letter that has not been read: Dreams in the Hebrew Bible |first=Shaul |last=Bar |publisher=Hebrew Union College Press |year=2001 |access-date=4 April 2013}}</ref>

[[Christians]] mostly shared the beliefs of the Hebrews and thought that dreams were of a supernatural character because the [[Old Testament]] includes frequent stories of dreams with divine inspiration. The most famous of these dream stories was [[Jacob's ladder|Jacob's dream of a ladder]] that stretches from Earth to [[Heaven]]. Many Christians preach that God can speak to people through their dreams. The famous glossary, the [[Somniale Danielis]], written in the name of [[Daniel (biblical figure)|Daniel]], attempted to teach Christian populations to interpret their dreams.

[[Iain R. Edgar]] has researched the role of dreams in [[Islam]].<ref>{{cite book |last=Edgar |first=Iain |title=The Dream in Islam: From Qur'anic Tradition to Jihadist Inspiration |year=2011 |publisher=Berghahn Books |location=Oxford |isbn=978-0-85745-235-1 |page=178 |url=http://www.berghahnbooks.com/title.php?rowtag=EdgarDream |url-status=dead |archive-url=https://web.archive.org/web/20110929125708/http://www.berghahnbooks.com/title.php?rowtag=EdgarDream |archive-date=29 September 2011 |access-date=9 March 2012}}</ref> He has argued that dreams play an important role in the history of Islam and the lives of Muslims, since dream interpretation is the only way that Muslims can receive revelations from God since the death of the last prophet, [[Muhammad]].<ref name="Iain">{{cite journal |last=Edgar |first=Iain R. |author2=Henig, David |title=Istikhara: The Guidance and practice of Islamic dream incubation through ethnographic comparison |journal=History and Anthropology |date=September 2010 |volume=21 |issue=3 |pages=251–262 |doi=10.1080/02757206.2010.496781 |url=https://core.ac.uk/download/pdf/10630.pdf |url-status=dead |archive-url=https://web.archive.org/web/20171108072540/https://core.ac.uk/download/pdf/10630.pdf |archive-date=8 November 2017 |citeseerx=10.1.1.1012.7334 |s2cid=144463607 |access-date=26 October 2017}}</ref> According to Edgar, Islam classifies three types of dreams.<ref>See Mufti Iqtadar Ahmad Khan, ''[[iarchive:tafseer-e-naeemi-17|Tafsir Naeemi: Vol. 17]]'', Naeemi Kutub Khana, 2014, Lahore, Part 17, Surah 21, Verses 4-7, “Scholarly Commentary,” p. 50, for a discussion of the three categories of dreams in Islamic tradition.</ref> Firstly, there is the true dream (al-ru’ya), then the false dream, which may come from the devil ([[shaytan]]), and finally, the meaningless everyday dream (hulm). This last dream could be brought forth by the dreamer's ego or base appetite based on what they experienced in the real world. The true dream is often indicated by Islam's [[hadith]] tradition.<ref name="Iain"/> In one narration by [[Aisha]], the wife of the Prophet, it is said that the Prophet's dreams would come true like the ocean's waves.<ref name="Iain"/> Just as in its predecessors, the [[Quran]] also recounts the story of Joseph and his unique ability to interpret dreams.<ref name="Iain"/>

In both Christianity and Islam dreams feature in conversion stories.<ref>{{Cite book |last=Bulkeley |first=Kelly |url=https://archive.org/details/big-dreams-the-science-of-dreaming-and-the-origins-of-religion |title=Big Dreams: The Science of Dreaming and the Origins of Religion |publisher=Oxford University Press |year=2016 |isbn=9780199351534}}</ref> According to ancient authors, Constantine the Great started his conversion to Christianity because he had a dream which prophesied that he would win the [[battle of the Milvian Bridge]] if he [[Constantine the Great#Constantine adopts the Greek letters Chi Rho for Christ's initials|adopted the Chi-Rho as his battle standard]]."<ref>Lactantius, ''De Mortibus Persecutorum'' 44.4–6, tr. J.L. Creed, ''Lactantius: De Mortibus Persecutorum'' (Oxford: Oxford University Press, 1984), qtd. in Lenski, "Reign of Constantine" (CC), 71.</ref><ref>Eusebius, ''Vita Constantini'' 1.27–29; Barnes, ''Constantine and Eusebius'', 43, 306; Odahl, 105–06, 319–20.</ref>

=== Buddhist ===
In Buddhism, ideas about dreams are similar to the classical and folk traditions in South Asia. The same dream is sometimes experienced by multiple people, as in the case of the [[bodhisattva#Theravada Buddhism|Buddha-to-be]], before he is [[great Renunciation|leaving his home]]. It is described in the ''[[Mahavastu|Mahāvastu]]'' that several of the Buddha's relatives had premonitory dreams preceding this. Some dreams are also seen to transcend time: the Buddha-to-be has certain dreams that are the same as those of [[List of the named Buddhas|previous Buddhas]], the ''[[Lalitavistara]]'' states. In Buddhist literature, dreams often function as a "signpost" motif to mark certain stages in the life of the main character.<ref name="Young 2003">{{cite encyclopedia |last=Young |first=S. |year=2003 |title=Dreams |via=Indian Folklife |volume=13 |url=http://indianfolklore.org/journals/index.php/IFL/article/download/434/497 |encyclopedia=The encyclopedia of South Asian Folklore |page=7 |url-status=dead |archive-url=https://web.archive.org/web/20180225064910/http://indianfolklore.org/journals/index.php/IFL/article/download/434/497 |archive-date=25 February 2018 |access-date=24 February 2018}}</ref>

Buddhist views about dreams are expressed in the [[atthakatha|Pāli Commentaries]] and the [[Milinda Panha|Milinda Pañhā]].<ref name="Young 2003"/>

=== Other ===
[[File:Hupao.jpg|thumb|[[Dreaming of the Tiger Spring]] (虎跑夢泉) Statue at Hupao Spring (Hupaomengquan) in Hangzhou, Zhejiang, China]]

In Chinese history, people wrote of two vital aspects of the soul of which one is freed from the body during slumber to journey in a dream realm, while the other remained in the body.<ref name=bulkeley-71/> This belief and dream interpretation had been questioned since early times, such as by the philosopher [[Wang Chong]] ({{CE|27–97}}).<ref name=bulkeley-71>{{cite book |last=Bulkeley |first=Kelly |title=Dreaming in the world's religions: A comparative history |url=https://archive.org/details/dreamingworldsre00bulk |url-access=limited |year=2008 |isbn=978-0-8147-9956-7 |pages=[https://archive.org/details/dreamingworldsre00bulk/page/n83 71]–73|publisher=NYU Press }}</ref>

The Babylonians and Assyrians divided dreams into "good," which were sent by the gods, and "bad," sent by demons.<ref>Oppenheim, L.A. (1966). ''Mantic Dreams in the Ancient Near East'' in G. E. Von Grunebaum & R. Caillois (Eds.), ''The Dream and Human Societies'' (pp. 341–350). London, England: Cambridge University Press.</ref> A surviving collection of dream omens entitled ''[[Iškar Zaqīqu]]'' records various dream scenarios as well as [[Prognosis|prognostications]] of what will happen to the person who experiences each dream, apparently based on previous cases.<ref name="BlackGreen1992"/><ref>Nils P. Heessel : ''Divinatorische Texte I : ... oneiromantische Omina''. Harrassowitz Verlag, 2007.</ref> Some list different possible outcomes, based on occasions in which people experienced similar dreams with different results.<ref name="BlackGreen1992"/> The Greeks shared their beliefs with the Egyptians on how to interpret good and bad dreams, and the idea of incubating dreams. [[Morpheus]], the Greek god of dreams, also sent warnings and prophecies to those who slept at shrines and temples. The earliest Greek beliefs about dreams were that their gods physically visited the dreamers, where they entered through a keyhole, exiting the same way after the divine message was given.

[[Antiphon (orator)|Antiphon]] wrote the first known Greek book on dreams in the 5th century BCE. In that century, other cultures influenced Greeks to develop the belief that souls left the sleeping body.<ref>O'Neil, C.W. (1976). ''Dreams, culture and the individual''. San Francisco: Chandler & Sharp.</ref> The father of modern medicine, [[Hippocrates]] ({{BCE|460–375}}), thought dreams could analyze illness and predict diseases.<ref>''On Regimen'' IV, also published sometimes as ''On Dreams''.</ref> For instance, a dream of a dim star high in the night sky indicated problems in the head region, while low in the night sky indicated bowel issues.<ref>{{Cite book |last=Hobson |first=J. A. |year=1988 |title=The Dreaming Brain |publisher=Basic Books}}</ref><ref>Steven M. Oberhelman. 1987. “The Diagnostic Dream in Ancient Medical Theory and Practice.” ''Bulletin of the History of Medicine''. 61 (1): 47-60.</ref> [[Galen]] (129–216 AD) believed the same thing.<ref>Oberhelman, Steven M. 1983. “Galen, ‘On Diagnosis from Dreams’.” ''Journal of the History of Medicine and Allied Sciences''. 38 (1): 36-47.</ref> Greek philosopher [[Plato]] (427–347 BCE) wrote that people harbor secret, repressed desires, such as incest, murder, adultery, and conquest, which build up during the day and run rampant during the night in dreams.<ref>{{Cite journal |last=McCurdy |first=H. G. |year=1946 |title=The history of dream theory |journal=Psychological Review |volume=53 |issue=4 |pages=225–233 |doi=10.1037/h0062107|pmid=20998507 }}</ref> Plato's student, [[Aristotle]] (384–322 BCE), believed dreams were caused by processing incomplete [[physiological]] activity during sleep, such as eyes trying to see while the sleeper's eyelids were closed.<ref>{{Cite book |last=Rycroft |first=Charles |year=1979 |title=The Innocence of Dreams |publisher=Random House}}</ref> [[Marcus Tullius Cicero]], for his part, believed that all dreams are produced by thoughts and conversations a dreamer had during the preceding days.<ref>Cicero, ''De Republica'', [http://attalus.org/translate/republic6.html#10 6.10]</ref> Cicero's ''[[Somnium Scipionis]]'' described a lengthy dream vision, which in turn was commented on by [[Macrobius]] in his ''Commentarii in Somnium Scipionis''.

[[Herodotus]] in his ''[[Histories (Herodotus)|The Histories]]'', writes "The visions that occur to us in dreams are, more often than not, the things we have been concerned about during the day."<ref>{{cite book |author=Herodotus |title=The Histories |year=1998 |url=https://archive.org/details/histories0000hero |url-access=registration |publisher=Oxford University Press |page=[https://archive.org/details/histories0000hero/page/414 414]}}</ref>

[[The Dreaming]] is a common term within the [[animist]] creation narrative of [[indigenous Australians]] for a personal, or group, [[Creation myth|creation]] and for what may be understood as the "timeless time" of formative creation and perpetual creating.<ref>[http://environment.gov.au/parks/uluru/culture-history/culture/index.html Uluru – Kata Tjuta National Park: Tjukurpa – Anangu culture] {{webarchive |url=https://web.archive.org/web/20090711104046/http://environment.gov.au/parks/uluru/culture-history/culture/index.html |date=11 July 2009}} environment.gov.au, June 23, 2006</ref>

Some [[Indigenous peoples of the Americas|Indigenous American]] tribes and [[Mexico|Mexican]] populations believe that dreams are a way of visiting and having contact with their [[ancestor]]s.<ref>{{cite journal |last1=Tedlock |first1=B. |year=1981 |title=Quiche Maya dream Interpretation |journal=Ethos |volume=9 |issue=4 |pages=313–350 |doi=10.1525/eth.1981.9.4.02a00050 |doi-access=free}}</ref> Some [[Indigenous peoples of the Americas|Native American]] tribes have used [[vision quest]]s as a rite of passage, fasting and praying until an anticipated guiding dream was received, to be shared with the rest of the tribe upon their return.<ref>{{cite web |url=http://www.dreams.ca/dreams.htm |last=Webb |first=Craig |year=1995 |title=Dreams: Practical Meaning & Applications |publisher=The DREAMS Foundation |url-status=dead |archive-url=https://web.archive.org/web/20160305002601/http://www.dreams.ca/dreams.htm |archive-date=5 March 2016 |access-date=30 March 2008}}</ref><ref>{{cite web |url=http://dreamhawk.com/dream-encyclopedia/native-american-dream-beliefs/ |access-date=10 April 2012 |title=Native American Dream Beliefs |publisher=Dream Encyclopedia |url-status=dead |archive-url=https://web.archive.org/web/20120415132211/http://dreamhawk.com/dream-encyclopedia/native-american-dream-beliefs/ |archive-date=15 April 2012}}</ref>

== Interpretation ==
{{Main|Dream interpretation}}
{{Further|Psychoanalysis|Precognition}}
[[File:Tissot Joseph Interprets Pharaoh's Dream.jpg|thumb|''Joseph Interprets Pharaoh's Dream'' c. 1896–1902. [[James Tissot|Jacques Joseph Tissot]] (1836–1902).]]

Beginning in the late 19th century, Austrian neurologist [[Sigmund Freud]], founder of [[psychoanalysis]], theorized that dreams reflect the dreamer's [[unconscious mind]] and specifically that dream content is shaped by unconscious wish fulfillment. He argued that important unconscious desires often relate to early childhood memories and experiences.<ref name="Freud1"/> [[Carl Jung]] and others expanded on Freud's idea that dream content reflects the dreamer's unconscious desires.

{{anchor|Veridical dream}}<!-- Target for [[Veridical dream]] -->
Dream interpretation can be a result of subjective ideas and experiences. One study found that most people believe that "their dreams reveal meaningful hidden truths".<ref name=":0">{{Cite journal |title=When dreaming is believing: The (motivated) interpretation of dreams. |journal=Journal of Personality and Social Psychology |pages=249–264 |volume=96 |issue=2 |doi=10.1037/a0013264 |first1=Carey K. |last1=Morewedge |first2=Michael I. |last2=Norton |s2cid=5706448 |pmid=19159131 |year=2009 |url=http://pdfs.semanticscholar.org/4f27/7783ada0dca0d236f368600f166fc7055524.pdf |archive-url=https://web.archive.org/web/20201114093642/http://pdfs.semanticscholar.org/4f27/7783ada0dca0d236f368600f166fc7055524.pdf |url-status=dead |archive-date=14 November 2020}}</ref> The researchers surveyed students in the United States, South Korea, and India, and found that 74% of Indians, 65% of South Koreans and 56% of Americans believed their dream content provided them with meaningful insight into their unconscious beliefs and desires. This Freudian view of dreaming was believed significantly more than theories of dreaming that attribute dream content to memory consolidation, problem-solving, or as a byproduct of unrelated brain activity. The same study found that people attribute more importance to dream content than to similar thought content that occurs while they are awake. Americans were more likely to report that they would intentionally miss their flight if they dreamt of their plane crashing than if they thought of their plane crashing the night before flying (while awake), and that they would be as likely to miss their flight if they dreamt of their plane crashing the night before their flight as if there was an actual plane crash on the route they intended to take. Participants in the study were more likely to perceive dreams to be meaningful when the content of dreams was in accordance with their beliefs and desires while awake. They were more likely to view a positive dream about a friend to be meaningful than a positive dream about someone they disliked, for example, and were more likely to view a negative dream about a person they disliked as meaningful than a negative dream about a person they liked.

According to surveys, it is common for people to feel their dreams are predicting subsequent life events.<ref name="hines"/> Psychologists have explained these experiences in terms of [[List of memory biases|memory biases]], namely a selective memory for accurate predictions and distorted memory so that dreams are retrospectively fitted onto life experiences.<ref name="hines">{{cite book |last=Hines |first=Terence |title=Pseudoscience and the Paranormal |publisher=Prometheus Books |year=2003 |pages=78–81 |isbn=978-1-57392-979-0}}</ref> The multi-faceted nature of dreams makes it easy to find connections between dream content and real events.<ref>{{cite book |last=Gilovich |first=Thomas |title=How We Know What Isn't So: the fallibility of human reason in everyday life |publisher=Simon & Schuster |year=1991 |pages=177–180 |isbn=978-0-02-911706-4}}</ref> The term "veridical dream" has been used to indicate dreams that reveal or contain truths not yet known to the dreamer, whether future events or secrets.<ref>{{Cite web |url=http://www.llewellyn.com/encyclopedia/term/Veridical+Dream |title=Llewellyn Worldwide – Encyclopedia: Term: Veridical Dream |website=www.llewellyn.com |access-date=16 October 2016 |url-status=dead |archive-url=https://web.archive.org/web/20161018202429/http://www.llewellyn.com/encyclopedia/term/Veridical+Dream |archive-date=18 October 2016}}</ref>

In one experiment, subjects were asked to write down their dreams in a diary. This prevented the selective memory effect, and the dreams no longer seemed accurate about the future.<ref>{{cite book |last=Alcock |first=James E. |title=Parapsychology: Science or Magic?: a psychological perspective |publisher=Pergamon Press |location=Oxford |year=1981 |isbn=978-0-08-025773-0}} via {{cite book |last=Hines |first=Terence |title=Pseudoscience and the Paranormal |publisher=Prometheus Books |year=2003 |pages=78–81 |isbn=978-1-57392-979-0}}</ref> Another experiment gave subjects a fake diary of a student with apparently precognitive dreams. This diary described events from the person's life, as well as some predictive dreams and some non-predictive dreams. When subjects were asked to recall the dreams they had read, they remembered more of the successful predictions than unsuccessful ones.<ref>{{cite journal |last=Madey |first=Scott |author2=Thomas Gilovich |title=Effects of Temporal Focus on the Recall of Expectancy-Consistent and Expectancy-Inconsistent Information |journal=Journal of Personality and Social Psychology |volume=65 |issue=3 |year=1993 |doi=10.1037/0022-3514.65.3.458 |pages=458–468 |pmid=8410650}} via {{cite book |last=Kida |first=Thomas |title=Don't Believe Everything You Think: The 6 Basic Mistakes We Make in Thinking |year=2006 |publisher=Prometheus Books |isbn=978-1-59102-408-8 |url=https://archive.org/details/dontbelieveevery00kida}}</ref>

== Images and literature ==
{{Main|Dream art}}
{{Further|Dream world (plot device)}}

Graphic artists, writers and filmmakers all have found dreams to offer a rich vein for creative expression. In the West, artists' depictions of dreams in Renaissance and Baroque art often were related to Biblical narrative. Especially preferred by visual artists were the [[Jacob's Ladder]] dream in Genesis and [[St. Joseph's dreams]] in the [[Gospel of Matthew|Gospel according to Matthew]].

<gallery>
File:Nicolas Dipre. Le songe de Jacob. c.1500 Avignon, Petit Palais..jpg|Nicolas Dipre. Le songe de Jacob. {{circa|1500}} Avignon, Petit Palais.
File:El sueño de Jacob, by José de Ribera, from Prado in Google Earth.jpg|José de Ribera (1591–1652). El sueño de Jacob, from Prado in Google Earth
File:Loggia_di_raffaello_08.jpg|Raphael. Jacob's Dream (1518)
File:Rembrandt Dream of Joseph.jpg|Rembrandt. Dream of Joseph (1645)
File:Mengs, Traum des hl. Joseph.jpg|Anton Raphael Mengs. Traum des Hl. Joseph (1773 or 1774)
</gallery>

Many later graphic artists have depicted dreams, including Japanese [[Woodblock printing in Japan|woodblock]] artist [[The Dream of the Fisherman's Wife|Hokusai]] (1760–1849) and Western European painters [[The Dream (Rousseau painting)|Rousseau]] (1844–1910), [[Le Rêve (Picasso)|Picasso]] (1881–1973), and [[Dream Caused by the Flight of a Bee Around a Pomegranate a Second Before Awakening|Dalí]] (1904–1989).

In literature, dream frames were frequently used in medieval allegory to justify the narrative; ''[[The Book of the Duchess]]''<ref>{{cite web |url=http://public.wsu.edu/~delahoyd/chaucer/BD.html |title=The book of the duchess|publisher=Washington State University |access-date=24 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121114035012/http://public.wsu.edu/~delahoyd/chaucer/BD.html |archive-date=14 November 2012}}</ref> and ''The Vision Concerning [[Piers Plowman]]''<ref>{{cite web |url=http://www.historyguide.org/ancient/langland.html |title=William Langland's The Vision Concerning Piers Plowman |publisher=The History Guide |access-date=24 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120606164224/http://www.historyguide.org/ancient/langland.html |archive-date=6 June 2012}}</ref> are two such [[dream vision]]s. Even before them, in antiquity, the same device had been used by [[Cicero]] and [[Lucian of Samosata]].

[[File:Alice par John Tenniel 24.png|thumb|''The cheshire cat'', [[John Tenniel]] (1820–1914), illustration in ''Alice's Adventures in Wonderland'', 1866 edition]]

Dreams have also featured in [[fantasy]] and [[speculative fiction]] since the 19th century. One of the best-known dream worlds is [[Wonderland (fictional country)|Wonderland]] from [[Lewis Carroll]]'s ''[[Alice's Adventures in Wonderland]]'', as well as [[Looking-Glass Land]] from its sequel, ''[[Through the Looking-Glass]]''. Unlike many dream worlds, Carroll's logic is like that of actual dreams, with transitions and flexible causality.

Other fictional dream worlds include the [[Dreamlands]] of [[H. P. Lovecraft]]'s ''[[Dream Cycle]]''<ref>{{cite book |last=Lovecraft |first=Howard Phillips |title=The Dream Cycle of H. P. Lovecraft: Dreams of Terror and Death |year=1995 |publisher=Ballantine Books |isbn=978-0-345-38421-8 |url=http://www.google.com/products/catalog?qscrl=1&nord=1&rlz=1T4ADFA_enUS369US375&ion=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1366&bih=564&wrapid=tlif133790017967410&q=h.p.+lovecraft+dream+cycle&um=1&tbm=shop&cid=7042018729009712854 |url-status=live |archive-url=https://web.archive.org/web/20130903092316/http://www.google.com/products/catalog?qscrl=1&nord=1&rlz=1T4ADFA_enUS369US375&ion=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1366&bih=564&wrapid=tlif133790017967410&q=h.p.+lovecraft+dream+cycle&um=1&tbm=shop&cid=7042018729009712854 |archive-date=3 September 2013}}</ref> and ''[[The Neverending Story]]''{{'}}s<ref>{{cite web |url=http://www.neverendingstory.com/ |title=The Neverending Story – Book – Pictures – Video – Icons |access-date=24 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120601055446/http://www.neverendingstory.com/ |archive-date=1 June 2012}}</ref> world of Fantastica, which includes places like the Desert of Lost Dreams, the Sea of Possibilities and the Swamps of Sadness. Dreamworlds, shared hallucinations and other alternate realities feature in a number of works by [[Philip K. Dick]], such as ''[[The Three Stigmata of Palmer Eldritch]]'' and ''[[Ubik]]''. Similar themes were explored by [[Jorge Luis Borges]], for instance in ''[[The Circular Ruins]]''.

Modern [[popular culture]] often conceives of dreams, as did Freud, as expressions of the dreamer's deepest fears and desires.<ref name="Van Riper 56">{{cite book |last=Van Riper |first=A. Bowdoin |title=Science in popular culture: a reference guide |publisher=[[Greenwood Press]] |location=Westport |year=2002 |pages=56–57 |isbn=978-0-313-31822-1}}</ref> In speculative fiction, the line between dreams and reality may be blurred even more in service to the story.<ref name="Van Riper 57">Van Riper, op. cit., p. 57.</ref> Dreams may be psychically invaded or manipulated (''[[Dreamscape (1984 film)|Dreamscape]]'', 1984; the ''[[A Nightmare on Elm Street (franchise)|Nightmare on Elm Street]]'' films, 1984–2010; ''[[Inception]]'', 2010) or even come literally true (as in ''[[The Lathe of Heaven]]'', 1971).<ref name="Van Riper 56"/>

== Lucidity ==
{{Main|Lucid dream}}

Lucid dreaming is the conscious perception of one's state while dreaming. In this state the dreamer may often have some degree of control over their own actions within the dream or even the characters and the environment of the dream. Dream control has been reported to improve with practiced deliberate lucid dreaming, but the ability to control aspects of the dream is not necessary for a dream to qualify as "lucid"—a lucid dream is any dream during which the dreamer knows they are dreaming.<ref>[http://www.psychwww.com/asc/ld/faq.html Lucid dreaming FAQ] {{webarchive|url=https://web.archive.org/web/20070313100513/http://www.psychwww.com/asc/ld/faq.html |date=13 March 2007}} by The Lucidity Institute at Psych Web.</ref> The occurrence of lucid dreaming has been scientifically verified.<ref name=Watanabe2003>{{cite journal |author=Watanabe, T. |year=2003 |title=Lucid Dreaming: Its Experimental Proof and Psychological Conditions |journal=J Int Soc Life Inf Sci |volume=21 |issue=1 |issn=1341-9226}}</ref>

"[[Oneironautics|Oneironaut]]" is a term sometimes used for those who lucidly dream.

In 1975, psychologist Keith Hearne successfully recorded a communication from a dreamer experiencing a lucid dream. On April 12, 1975, after agreeing to move his eyes left and right upon becoming lucid, the subject and Hearne's co-author on the resulting article, Alan Worsley, successfully carried out this task.<ref name="Lucid dream communication">{{cite web |url=http://www.keithhearne.com/wp-content/uploads/2010/06/RECHTSCHAFFEN.pdf |title=The University of Chicago Department of Psychiatry |date=5 September 1975 |access-date=21 October 2013 |url-status=dead |archive-url=https://web.archive.org/web/20120426081653/http://www.keithhearne.com/wp-content/uploads/2010/06/RECHTSCHAFFEN.pdf |archive-date=26 April 2012}}</ref> Years later, psychophysiologist [[Stephen LaBerge]] conducted similar work including:
* Using eye signals to map the subjective sense of time in dreams.
* Comparing the electrical activity of the brain while singing awake and while dreaming.
* Studies comparing in-dream sex, arousal, and orgasm.<ref>{{cite book|doi=10.1037/14258-006 |chapter=Lucid dreaming: Paradoxes of dreaming consciousness |title=Varieties of anomalous experience: Examining the scientific evidence |edition=2nd |date=2014 |last1=Laberge |first1=Stephen |pages=145–173 |isbn=978-1-4338-1529-4 |s2cid=152082735 }}
</ref>
Communication between two dreamers has also been documented. The processes involved included [[Electroencephalography|EEG]] monitoring, ocular signaling, incorporation of reality in the form of red light stimuli and a coordinating website. The website tracked when both dreamers were dreaming and sent the stimulus to one of the dreamers where it was incorporated into the dream. This dreamer, upon becoming lucid, signaled with eye movements; this was detected by the website whereupon the stimulus was sent to the second dreamer, invoking incorporation into that dreamer's dream.<ref>{{Cite web |url=https://www.forbes.com/sites/parmyolson/2012/11/08/saying-hi-through-a-dream-how-the-internet-could-make-sleeping-more-social/#2eb99101590c |title=Saying 'Hi' Through A Dream: How The Internet Could Make Sleeping More Social |last=Olson |first=Parmy |website=Forbes |access-date=24 April 2016 |url-status=live |archive-url=https://web.archive.org/web/20160531010710/http://www.forbes.com/sites/parmyolson/2012/11/08/saying-hi-through-a-dream-how-the-internet-could-make-sleeping-more-social/#2eb99101590c |archive-date=31 May 2016}}</ref>

== Recollection ==
{{Further|Dream diary}}
[[File:Riepenhausen Raphael's dream.jpg|thumb|left|''Raphael's dream'' (1821). [[Johannes Riepenhausen]] and Franz Riepenhausen.]]

The recollection of dreams is extremely unreliable, though it is a skill that can be trained. Dreams can usually be recalled if a person is awakened while dreaming.<ref name="npr"/> Women tend to have more frequent dream recall than men.<ref name="npr">{{cite web |url=https://www.npr.org/templates/story/story.php?storyId=15778923 |title=The Science Behind Dreams and Nightmares |website=NPR.org |date=30 October 2007 |access-date=4 April 2013 |url-status=live |archive-url=https://web.archive.org/web/20130822180530/http://www.npr.org/templates/story/story.php?storyId=15778923 |archive-date=22 August 2013}}</ref> Dreams that are difficult to recall may be characterized by relatively little [[affect (psychology)|affect]], and factors such as [[salience (neuroscience)|salience]], [[arousal]], and interference play a role in dream recall. Often, a dream may be recalled upon viewing or hearing a random trigger or stimulus. The [[Graded Salience Hypothesis|salience hypothesis]] proposes that dream content that is salient, that is, novel, intense, or unusual, is more easily remembered. There is considerable evidence that vivid, intense, or unusual dream content is more frequently recalled.<ref name=Watson>{{cite journal |doi=10.1016/S0191-8869(02)00114-9 |title=To dream, perchance to remember: Individual differences in dream recall |year=2003 |last1=Watson |first1=David |journal=Personality and Individual Differences |volume=34 |issue=7 |pages=1271–1286}}</ref> A [[dream journal]] can be used to assist dream recall, for personal interest or [[psychotherapy]] purposes.

Adults report remembering around two dreams per week, on average.<ref>{{cite news |title=Why Do Some People Always Remember Their Dreams, While Others Almost Never Do? |url=https://www.discovermagazine.com/mind/why-do-some-people-always-remember-their-dreams-while-others-almost-never |access-date=10 February 2021 |work=Discover Magazine |date=2019}}</ref><ref>{{cite journal |last1=Herlin |first1=Bastien |last2=Leu-Semenescu |first2=Smaranda |last3=Chaumereuil |first3=Charlotte |last4=Arnulf |first4=Isabelle |title=Evidence that non-dreamers do dream: a REM sleep behaviour disorder model |journal=Journal of Sleep Research |date=December 2015 |volume=24 |issue=6 |pages=602–609 |doi=10.1111/jsr.12323 |pmid=26307463 |quote=Adults report, on average, 1–2.8 dream recalls per week in a dream questionnaire and 2.38 dream recalls per week when a home dream diary is completed |doi-access=free}}</ref> Unless a dream is particularly vivid and if one wakes during or immediately after it, the content of the dream is typically not remembered.<ref>{{cite journal |last1=Hobson |first1=J.A. |last2=McCarly |first2=R.W. |s2cid=10396934 |year=1977 |title=The brain as a dream-state generator: An activation-synthesis hypothesis of the dream process |journal=American Journal of Psychiatry |volume=134 |issue=12 |pages=1335–1348 |pmid=21570 |doi=10.1176/ajp.134.12.1335 |url=https://pdfs.semanticscholar.org/f1af/886bfac2ee058ddaf1a6fb61dabe08e19b08.pdf |archive-url=https://web.archive.org/web/20170709221130/https://pdfs.semanticscholar.org/f1af/886bfac2ee058ddaf1a6fb61dabe08e19b08.pdf |url-status=dead |archive-date=9 July 2017}}</ref>

In line with the salience hypothesis, there is considerable evidence that people who have more vivid, intense or unusual dreams show better recall. There is evidence that continuity of consciousness is related to recall. Specifically, people who have vivid and unusual experiences during the day tend to have more memorable dream content and hence better dream recall. People who score high on measures of personality traits associated with creativity, imagination, and fantasy, such as [[openness to experience]], [[daydream]]ing, [[fantasy prone personality|fantasy proneness]], [[absorption (psychology)|absorption]], and [[hypnotic susceptibility]], tend to show more frequent dream recall.<ref name= Watson/> There is also evidence for continuity between the bizarre aspects of dreaming and waking experience. That is, people who report more bizarre experiences during the day, such as people high in [[schizotypy]] (psychosis proneness), have more frequent dream recall and also report more frequent [[nightmare]]s.<ref name= Watson/>

=== Dream-recording machine ===
Recording or reconstructing dreams may one day assist with dream recall.<ref name="Underwood-2013-Science-Dream-Machine">{{cite journal |last1=Underwood |first1=Emily |title=How to Build a Dream-Reading Machine |journal=Science |date=5 April 2013 |volume=340 |issue=6128 |pages=21 |doi=10.1126/science.340.6128.21 |pmid=23559230 |url=https://www.science.org/doi/10.1126/science.340.6128.21 |access-date=15 May 2023 |language=en |issn=0036-8075|url-access=subscription }}</ref><ref>{{Cite web |last=Hawks |first=Charlotte |date=April 5, 2018 |title=How close are we to video-recording our dreams? |url=https://edition.cnn.com/2018/04/04/health/recording-our-dreams/index.html |website=CNN}}</ref> Using the permitted non-invasive technologies, functional magnetic resonance imaging (fMRI) and [[electromyography]] (EMG), researchers have been able to identify basic dream imagery,<ref>{{Cite news |url=https://www.bbc.com/news/science-environment-22031074 |title=Scientists 'read dreams' using brain scans |website=BBC News |access-date=24 April 2016 |url-status=live |archive-url=https://web.archive.org/web/20160427185103/http://www.bbc.com/news/science-environment-22031074 |archive-date=27 April 2016 |date=4 April 2013 |last1=Morelle |first1=Rebecca |author-link=Rebecca Morelle}}</ref> [[dream speech]] activity<ref>{{Cite book |url=https://books.google.com/books?id=esv8GMVwHwEC |title=The Psychophysiology of Thinking: Studies of Covert Processes |last=Mcguigan |first=F. |year=2012 |publisher=Elsevier |isbn=978-0-323-14700-2}}</ref> and dream motor behavior (such as walking and hand movements).<ref>{{Cite book |url=https://books.google.com/books?id=n6YXNrpA8ZYC |title=States of Consciousness: Experimental Insights into Meditation, Waking, Sleep and Dreams |last1=Cvetkovic |first1=Dean |last2=Cosic |first2=Irena |year=2011 |publisher=Springer Science & Business Media |isbn=978-3-642-18047-7}}</ref><ref>{{Cite web |url=https://huffingtonpost.com/dreamscloud/can-we-turn-our-dreams-in_b_9152612.html |title=Can We Turn Our Dreams Into Watchable Movies? |last=Oldis |first=Daniel |website=The Huffington Post |access-date=2016-08-20 |url-status=live |archive-url=https://web.archive.org/web/20160804163822/http://www.huffingtonpost.com/dreamscloud/can-we-turn-our-dreams-in_b_9152612.html |archive-date=4 August 2016 |date=4 February 2016}}</ref>

== Miscellany ==
=== Illusion of reality ===
{{Main|Dream argument}}

Some philosophers have proposed that what we think of as the "real world" could be or is an illusion (an idea known as the [[skeptical hypothesis]] about [[ontology]]). The first recorded mention of the idea was in the 4th century BCE by [[Zhuang Zhou|Zhuangzi]], and in Eastern philosophy, the problem has been named the "[[Zhuangzi (book)#"The Butterfly Dream"|Zhuangzi Paradox]]."
<blockquote>He who dreams of drinking wine may weep when morning comes; he who dreams of weeping may in the morning go off to hunt. While he is dreaming he does not know it is a dream, and in his dream he may even try to interpret a dream. Only after he wakes does he know it was a dream. And someday there will be a great awakening when we know that this is all a great dream. Yet the stupid believe they are awake, busily and brightly assuming they understand things, calling this man ruler, that one herdsman—how dense! Confucius and you are both dreaming! And when I say you are dreaming, I am dreaming, too. Words like these will be labeled the Supreme Swindle. Yet, after ten thousand generations, a great sage may appear who will know their meaning, and it will still be as though he appeared with astonishing speed.<ref>莊子, 齊物論, 12. ''Zhuàngzi'', "Discussion on making all things equal," 12. ''from'' Zhuàngzi, Burton Watson trans., ''Chuang Tzu'' (New York: Columbia University Press, 1996), 43. {{ISBN|978-0-231-10595-8}} [https://books.google.com/books?id=f1BvUUUVRLEC&pg=PA43]</ref></blockquote>

The idea also is discussed in Hindu and Buddhist writings.<ref>{{cite book |title=Buddhism As Presented by the Brahmanical Systems |last=Kher |first=Chitrarekha V. |year=1992 |publisher=Sri Satguru Publications |isbn=978-81-7030-293-3}}</ref> It was formally introduced to Western philosophy by [[Descartes]] in the 17th century in his ''[[Meditations on First Philosophy]]''.

=== Absent-minded transgression ===
Dreams of absent-minded transgression (DAMT) are dreams wherein the dreamer absent-mindedly performs an action that he or she has been trying to stop (one classic example is of a quitting smoker having dreams of lighting a cigarette). Subjects who have had DAMT have reported waking with intense feelings of [[guilt (emotion)|guilt]]. One study found a positive association between having these dreams and successfully stopping the behavior.<ref>{{cite journal |vauthors=Hajek P, Belcher M |title=Dream of absent-minded transgression: an empirical study of a cognitive withdrawal symptom |journal=J Abnorm Psychol |volume=100 |issue=4 |pages=487–491 |year=1991 |pmid=1757662 |doi=10.1037/0021-843X.100.4.487}}</ref>

===Non-REM dreams===
Hypnogogic and hypnopompic dreams, dreamlike states shortly after falling asleep and shortly before awakening, and dreams during stage 2 of [[Non-rapid eye movement sleep|NREM-sleep]], also occur, but are shorter than REM-dreams.<ref>{{Cite web|url=https://www.psychologytoday.com/us/blog/dreaming-in-the-digital-age/201712/the-science-dreaming-9-key-points|title=The Science of Dreaming: 9 Key Points &#124; Psychology Today|website=www.psychologytoday.com}}</ref><ref>[https://www.nlm.nih.gov/pmc/articles/PMC7590944/ Dormio: A Targeted Dream Incubation Device – PMC – NCBI]{{dead link|date=July 2025|bot=medic}}{{cbignore|bot=medic}}</ref>

=== Daydreams ===
{{Main|Daydream}}
[[File:Joseph Noel Paton - Dante Meditating.jpg|thumb|left|''Dante Meditating'', 1852, by [[Joseph Noel Paton]]]]

A daydream is a visionary [[fantasy (psychology)|fantasy]], especially one of happy, pleasant thoughts, hopes or ambitions, imagined as coming to pass, and experienced while awake.<ref name="Klinger">Klinger, Eric (October 1987). ''[[Psychology Today]]''.</ref> There are many different types of daydreams, and there is no consistent definition amongst psychologists.<ref name="Klinger"/> The general public also uses the term for a broad variety of experiences. Research by Harvard psychologist [[Deirdre Barrett]] has found that people who experience vivid dreamlike [[mental image]]s reserve the word for these, whereas many other people refer to milder imagery, realistic future planning, review of memories or just "spacing out"—i.e. one's mind going relatively blank—when they talk about "daydreaming".<ref>{{cite journal |last1=Barrett |first1=D.L. |year=1979 |title=The Hypnotic Dream: Its Content in Comparison to Nocturnal Dreams and Waking Fantasy |journal=Journal of Abnormal Psychology |volume=88 |issue=5 |pages=584–591 |doi=10.1037/0021-843x.88.5.584}}</ref><ref>Barrett, D.L. "Fantasizers and Dissociaters: Two types of High Hypnotizables, Two Imagery Styles". in R. Kusendorf, N. Spanos, & B. Wallace (Eds.) ''Hypnosis and Imagination''. New York: Baywood, 1996. and,  Barrett, D.L. "Dissociaters, Fantasizers, and their Relation to Hypnotizability" in Barrett, D.L. (Ed.) ''Hypnosis and Hypnotherapy'', (2 vol.): Vol. 1: ''History, theory and general research'', Vol. 2: ''Psychotherapy research and applications'', New York: Praeger/Greenwood, 2010.</ref>

While daydreaming has long been derided as a lazy, non-productive pastime, it is now commonly acknowledged that daydreaming can be constructive in some contexts.<ref>{{cite news |first=John |last=Tierney |author-link=John Tierney (journalist) |title=Discovering the Virtues of a Wandering Mind |url=https://www.nytimes.com/2010/06/29/science/29tier.html |newspaper=[[The New York Times]] |date=28 June 2010 |url-status=live |archive-url=https://web.archive.org/web/20170421104306/http://www.nytimes.com/2010/06/29/science/29tier.html |archive-date=21 April 2017}}</ref> There are numerous examples of people in creative or artistic careers, such as composers, novelists and filmmakers, developing new ideas through daydreaming. Similarly, research scientists, mathematicians and physicists have developed new ideas by daydreaming about their subject areas.

=== Hallucination ===
{{Main|Hallucination}}

A hallucination, in the broadest sense of the word, is a [[perception]] in the absence of a [[stimulus (physiology)|stimulus]]. In a stricter sense, hallucinations are perceptions in a conscious and awake state, in the absence of external stimuli, and have qualities of real perception, in that they are vivid, substantial, and located in external objective space. The latter definition distinguishes hallucinations from the related phenomena of dreaming, which does not involve wakefulness.

=== Nightmare ===
{{Main|Nightmare}}
[[File:A perturbed young woman fast asleep Wellcome V0016638.jpg|thumb|Woman having a nightmare. Jean-Pierre Simon (1764–1810 or 1813).]]

A nightmare is an unpleasant dream that can cause a strong [[negative emotion]]al response from the mind, typically [[fear]] or [[horror and terror|horror]], but also [[despair]], [[anxiety]] and great [[sadness]]. The dream may contain situations of danger, discomfort, psychological or physical terror. Sufferers usually awaken in a state of distress and may be unable to return to [[sleep]] for a prolonged period of time.<ref>American Psychiatric Association (2000), Diagnostic and Statistical Manual of Mental Disorders, 4th ed, TR, p. 631</ref>

=== Night terror ===
{{Main|Night terror}}

A night terror, also known as a sleep terror or ''pavor nocturnus'', is a [[parasomnia]] [[sleep disorder|disorder]] that predominantly affects children, causing feelings of terror or dread. Night terrors should not be confused with [[nightmare]]s, which are bad dreams that cause the feeling of horror or fear.<ref>{{cite book |last1=Hockenbury |first1=Don H. |last2=Hockenbury |first2=Sandra E. |title=Discovering psychology |date=2010 |publisher=Worth Publishers |location=New York |isbn=978-1-4292-1650-0 |edition=5th |page=157}}</ref>

=== Déjà vu ===
{{Main|Déjà vu}}

One theory of déjà vu attributes the feeling of having previously seen or experienced something to having dreamed about a similar situation or place, and forgetting about it until one seems to be mysteriously reminded of the situation or the place while awake.<ref>{{cite book |title=The Dream Directory: The Comprehensive Guide to Analysis and Interpretation |last=Lohff |first=David C. |year=2004 |publisher=Running Press |isbn=978-0-7624-1962-3 |url=https://archive.org/details/davidclohffsdrea0000lohf}}</ref>

=== Melatonin ===
{{Main|Melatonin}}

Melatonin is a natural hormone secreted by the brain's [[pineal gland]], inducing nocturnal behaviors in animals and sleep in humans during nighttime.  Chemically isolated in 1958,  melatonin has been marketed as a [[sleep aid]] since the 1990s and is currently sold in the United States as an over-the-counter product requiring no prescription.  Anecdotal reports and formal research studies over the past few decades have established a link between melatonin supplementation and more vivid dreams.<ref>{{cite journal |title=Effects of melatonin on dream bizarreness among male and female college students.|last=Kahan |first=Tracey L.  |year=2000 |journal=Sleep and Hypnosis |volume=2 |issue=2 |pages=74–83|url=https://scholarcommons.scu.edu/psych/102/}}</ref>

== See also ==
{{Portal|Psychology}}
<!-- Please keep entries in alphabetical order & add a short description [[WP:SEEALSO]] -->
{{div col|colwidth=12em}}
* [[Dream dictionary]]
* [[Dream incubation]]
* [[Welsh mythology#The Dream of Macsen Wledig|Dream of Macsen Wledig]]
* [[Dream pop]]
* [[Dream sequence]]
* [[Dream yoga]]
* [[Dreamcatcher]]
* [[Dreams in analytical psychology]]
* [[Dreamwork]]
* [[False awakening]]
* ''[[Hatsuyume]]''
* [[Incubus]]
* [[Lilith]], a Sumerian dream demoness
* [[List of dream diaries]]
* [[Mare (folklore)]]
* [[Mabinogion]]
* [[Recurring dream]]
* [[Sleep in animals]]
* [[Sleep paralysis]]
* [[Spirit spouse]]
* [[Succubus]]
* [[Works based on dreams]]
{{div col end}}
<!-- please keep entries in alphabetical order -->

== References ==
{{Reflist}}

== Further reading ==
* ''[[Dreaming (journal)|Dreaming]]'' – journal published by the [[American Psychological Association]]
* {{cite book |author=Jung, Carl |author-link=Carl Jung |title=The Practice of Psychotherapy. ''"The Practical Use of Dream-analysis"'' |location=New York |year=1934 |pages=139– |isbn=978-0-7100-1645-4 |publisher= Routledge & Kegan Paul }}
* {{cite book |author=Jung, Carl |title=Dreams (Routledge Classics) |publisher=Routledge |location=New York |year=2002 |isbn=978-0-415-26740-3}}
* Harris, William V. (2009) ''Dreams and Еxperience in Classical Antiquity''. Cambridge, MA & London: Harvard University Press. {{isbn|978-0-674-03297-2}}

== External links ==
{{Commons category|Dreams}}
{{wikiquote}}
* {{In Our Time|Dreams|p004y23x|Dreams}}
* [http://aras.org/ Archive for Research in Archetypal Symbolism website]
* [http://www.asdreams.org/ The International Association for the Study of Dreams]
* {{Cite news |first=Jay |last=Dixit |title=Dreams: Night School |url=https://www.psychologytoday.com/us/articles/200711/dreams-night-school |magazine=[[Psychology Today]] |date=November 2007 |access-date=December 1, 2018}}
* [https://groups.google.com/forum/#!forum/alt.dreams/ alt.dreams] A long-running USENET forum wherein readers post and analyze dreams
* [http://lsdbase.org/ LSDBase] – online sleep research database documenting physiological effects of dreams through biofeedback
{{Dreaming}}
{{SleepSeries2}}
{{Authority control}}

[[Category:Dream| ]]
[[Category:Night]]
[[Category:Sleep]]
[[Category:Symbols]]