Hypnagogia 888915 226165396 2008-07-17T03:07:55Z 220.253.11.62 /* Artistic and cultural references */ '''Hypnagogia''' ([[Ancient Greek|Greek]] ὕπνος, ''húpnos'' "sleep" + the [[root (linguistics)|root]] found in ἄγω, ''ágō'' "to lead away, conduct, convey", ἀγωγεύς, ''agōgeús'' "conveyor", ἀγωγή, ''agōgḗ'' "abduction, transport, leading away" etc.), often misspelled ''hypnogogia'', is a term coined by [[Louis Ferdinand Alfred Maury|Alfred Maury]] for the transitional state between [[wakefulness]] and [[sleep]].<ref>Maury, Louis Ferdinand Alfred (1848). ‘Des hallucinations hypnagogiques, ou des erreurs des sens dans l'etat intermediaire entre la veille et le sommeil’. ''Annales Medico-Psychologiques du système nerveux'', 11, 26-40.</ref><ref>{{cite book | title = Le sommeil et les rêves: études psychologiques sur ces phénomènes et les divers états qui s'y rattachent, suivies de recherches sur le developpement de l'instinct et de l'intelligence dans leurs rapports avec le phénomène du sommeil | first = Louis Ferdinand Alfred | last = Maury | publisher = Paris: Didier | year = 1865 | isbn = }}</ref> [[Image:John Henry Fuseli - The Nightmare.JPG|thumb|300px|[[The Nightmare]] by [[Henry Fuseli]]. Chest pressure is sometimes felt in [[sleep paralysis]], a not uncommon hypnagogic experience.]] ==Definitions and synonyms== Sometimes the word ''hypnagogia'' is used in a restricted [[word sense|sense]] to refer to the onset of sleep, and contrasted with ''[[hypnopompia]]'', [[Frederic William Henry Myers|Fredierick Myers’]] term for waking up.<ref>{{cite book | title = Human Personality and Its Survival of Bodily Death | first = Frederic | last = Myers | publisher = London: Longmans | year = 1903 | isbn = }}</ref> However, ''hypnagogia'' is also regularly employed in a more general sense that covers both falling asleep and waking up, and [[Havelock Ellis]] questioned the need for separate terms.<ref>{{cite book | title = Hypnagogia: the Unique State of Consciousness Between Wakefulness and Sleep | first = Andreas | last = Mavromatis | publisher = London: Routledge and Kegan Paul | year = 1987 | isbn = 0710202822}} p. 1.</ref> Indeed, it is not always possible in practice to assign a particular episode of any given [[phenomenon (science)|phenomenon]] to one or the other, given that the same kinds of [[subjective experience|experience]] occur in both, and that people may drift in and out of sleep. In this article ''hypnagogia'' will be used in the broader sense, unless otherwise stated or implied. Other terms for hypnagogia, in one or both senses, that have been proposed include ‘presomnal’ or ‘anthypnic sensations’, ‘visions of half-sleep’, ‘oneirogogic images’ and ‘phantasmata’,<ref>Mavromatis, op. cit., p. 1.</ref>, ‘the borderland of sleep’, ‘praedormitium’,<ref> Mavromatis, op. cit., p. 4.</ref> the ‘borderland state’, ‘half-dream state’, ‘pre-dream condition’<ref> Lachman, Gary (2002). [http://www.forteantimes.com/features/articles/227/hypnagogia.html ‘Hypnagogia’]. ''Fortean Times''.</ref> ‘sleep onset dreams’,<ref>Stickgold, R., interviewed 30 October 2000 by Norman Swan for ''Health Report'' on Australia’s [[Radio National]] ([http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s206232.htm transcript]), retrieved 3 July 2008.</ref> dreamlets.<ref>Schacter, D. L. (1976). The hypnagogic state: A critical review of the literature. Psychological Bulletin, 83, 452–481.</ref> and ‘wakefulness-sleep transition’ state (WST).<ref>{{cite web |title=Róbert Bódizs, Melinda Sverteczki and Eszter Mészáros, ''Wakefulness-sleep transition: Emerging electroencephalographic similarities with the rapid eye movement phase'',| url=http://www.sciencedirect.com/science/article/B6SYT-4RCN8CP-1/2/eee96a80f27593096fdace6bb9fce440|accessdate=2008-03-31}}</ref> ==History== Early references to hypnagogia are to be found in the writings of [[Aristotle]], [[Iamblichus]], [[Cardano]], [[Simon Forman]] and [[Swedenborg]].<ref>Mavromatis, op. cit. pp. 3-4.</ref> [[Romanticism]] brought a renewed interest in the subjective experience of the edges of sleep.<ref>Pfotenhauer, Helmut & Schneider, Sabine (2006). ''Nicht völlig wachen und nicht ganz ein Traum: Die Halfschlafbilder in der Literatur''. Verlag Königshausen & Neumann. ISBN 3826032748.</ref> In more recent centuries, many authors have referred to the state; [[Edgar Allan Poe]], for example, wrote of the ‘fancies’ he experienced “only when I am on the brink of sleep, with the consciousness that I am so.”<ref>Quoted by Mavromatis, op. cit., p. 4.</ref> Serious scientific enquiry began in the 19th century with [[Johannes Peter Müller]], [[Jules Baillarger]] and [[Louis Ferdinand Alfred Maury|Alfred Maury]], and continued into the twentieth with Leroy.<ref>Leroy, E. B. (1933). ''Les visions du demi-sommeil''. Paris: Alcan.</ref> The advent of [[electroencephalography]] has allowed the introspective methods of these early researchers to be supplemented with physiological data. The search for neural correlates for hypnagogic imagery began with Davis et al. in the 1930s,<ref>Davis, H., Davis, P. A., Loomis, A. L., Harvey, E. N., & Hobart, G. (1937) ‘Changes in human brain potentials during the onset of sleep’. ''Science'' 86, 448–50.</ref> and continues with increasing sophistication to this day. While the dominance of the [[behaviourism|behavourist]] paradigm led to a decline in research, especially in the English speaking world, the later 20th century has seen a revival, with investigations of hypnagogia and related [[altered state of consciousness|ASCs]] playing an important role in the emerging multidisciplinary study of [[consciousness]].<ref>Vaitl et al. (2005) ‘[http://www.mp.uni-tuebingen.de/mp/fileadmin/user_upload/Kotchoubey/Vaitl-2005-ASC.pdf Psychobiology of altered states of consciousness]’. ''Psychological Bulletin'' 131:1.</ref><ref>{{ cite book | title = Consciousness: An Introduction | first = Susan | last = Blackmore | publisher = London: Hodder & Stoughton | year = 2003 | isbn = 0-340-80909-4 }}</ref> Nevertheless, much remains to be understood about the experience and its corresponding neurology, and the topic has been somewhat neglected in comparison with sleep and dreams; hypnagogia has been described as a “well-trodden and yet unmapped territory.”<ref>Mavromatis, op. cit., p. xiii.</ref> Important reviews of the scientific literature have been made by Leaning,<ref>Leaning, F. E. (1925). ''An introductory study of hypnagogic phenomena''.</ref> [[Daniel Schacter|Schacter]], <ref>Schacter, D. L. (1976). The hypnagogic state: A critical review of the literature. ''Psychological Bulletin'', 83, 452–481.</ref> Richardson and Mavromatis.<ref>Mavromatis, op. cit., p. 1.</ref> ==Sensory phenomena== Transition to and from [[sleep]] may be attended by a wide variety of [[sense|sensory]] experiences. These can occur in any modality, individually or combined, and range from the vague and barely perceptible to vivid [[hallucination]]s.<ref>Mavromatis, op. cit. p. 14.</ref> ===Sights=== Among the more commonly reported,<ref>Hori, T., Hayashi, M., & Morikawa, T. (1993). [[EEG topography|Topographical]] EEG changes and hypnagogic experience. In: Ogilvie, R.D., & Harsh, J.R. (Eds.) Sleep Onset: Normal and Abnormal Processes, pp. 237-53.</ref><ref>Germaine, A. & Nielsen T. A. (1997). ‘Distribution of spontaneous hypnagogic images across Hori's EEG stages of sleep onset’. ''Sleep Research'' 26, p. 243.</ref> and more thoroughly researched, sensory features of hypnagogia are [[phosphenes]], also called ‘[[entoptic]] phenomena’. Hypnagogic phosphenes can manifest as seemingly random speckles, lines or geometrical patterns, including [[form constants]], or as [[figurative art|figurative]] (representational) [[mental image|images]]. They may be [[monochrome|monochromatic]] or richly [[colour|coloured]], still or moving, flat or three-dimensional (offering an impression of [[perspective]]). Individual images are typically fleeting and given to very rapid changes. They are said to differ from [[dreams]] proper in that hypnagogic imagery is usually static and lacking in [[narrative]] content,<ref>Vaitl et al. (2005) ‘[http://www.mp.uni-tuebingen.de/mp/fileadmin/user_upload/Kotchoubey/Vaitl-2005-ASC.pdf Psychobiology of altered states of consciousness]’. ''Psychological Bulletin'' 131:1.</ref> although others understand the state rather as a gradual transition from hypnagogia to fragmentary dreams,<ref> Lehmann, D., Grass, P., & Meier, B. (1995). ‘Spontaneous conscious covert cognition states and brain electric spectral states in canonical correlations’. ''International Journal of Psychophysiology'', 19, 41–52.</ref> i.e. from simple ‘[[eigengrau|eigenlicht]]’ to whole [[imagination|imagined]] scenes. Descriptions of exceptionally vivid and elaborate hypnagogic visuals can be found in the work of [[Marie-Jean-Léon, Marquis d'Hervey de Saint Denys]]. ===The ‘Tetris Effect’=== People who have spent a long time at some repetitive activity before sleep, in particular one that is new to them, may find that it dominates their imagery as they grow [[somnolence|drowsy]], a tendency dubbed the [[Tetris effect]]. This effect has even been observed in [[amnesia|amnesiacs]] who otherwise have no [[memory]] of the original activity.<ref>Stickgold, R., Malia, A., Maguire, D., Roddenberry, D., & O’Connor, M. (2000). ‘Replaying the game: Hypnagogic images in normals and amnesics’. ''Science'', 290(5490), pp. 350–3.</ref> When the activity involves moving objects, as in the computer game [[Tetris]], the corresponding hypnagogic images too tend to be perceived as moving. The Tetris effect is not confined to visual imagery, but can manifest in other modalities also. For example, [[Robert Stickgold]] recounts having experienced the touch of rocks while falling asleep after mountain climbing.<ref>Stickgold, R., interviewed 30 October 2000 by Norman Swan for ''Health Report'' on Australia’s [[Radio National]] ([http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s206232.htm transcript]), retrieved 3 July 2008.</ref> ===Sounds=== Hypnagogic imagery is often auditory or has an auditory component. Like the visuals, hypnagogic sounds vary in intensity from faint impressions to loud noises, such as crashes and bangs ([[exploding head syndrome]]). People may imagine their own name called or a doorbell ringing. Snatches of imagined [[spoken language|speech]] are common. While typically [[nonsense|nonsensical]] and fragmented, these speech events can occasionally strike the individual as apt comments on – or summations of – their [[thought]]s at the time. They often contain [[wordplay]], [[neologism]]s and made-up [[name]]s. Hypnagogic speech may manifest as the subject’s own ‘[[internal monologue|inner voice]]’, or as the voices of others: familiar people or strangers. More rarely, [[poetry]] or [[music]] are heard.<ref>Mavromatis, op. cit., p. 81.</ref> ===Sleep paralysis=== Humming, roaring, hissing, rushing and buzzing noises are frequent in conjunction with [[sleep paralysis]] (SP). This happens when the [[REM atonia]] sets in sooner than usual, before the person is fully asleep, or persists longer than usual, after the person has (in other respects) fully awoken.<ref>{{ cite book | title = Consciousness: An Introduction | first = Susan | last = Blackmore | publisher = London: Hodder & Stoughton | year = 2003 | isbn = 0-340-80909-4 }}</ref> SP is reportedly very frequent among [[narcolepsy|narcoleptics]]. It occurs frequently in about 6% of the rest of the population, and occurs occasionally in 60%.<ref>Thorpy, M. J. (ed). (1990). ‘Sleep paralysis’. ''ICSD-International Classification of Sleep Disorders: Diagnostic and Coding Manual''. Rochester, Minn.: American Sleep Disorders Association.</ref> In surveys from Canada, China, England, Japan and Nigeria, 20 to 60% of individuals reported having experienced SP at least once in their lifetime.<ref>Blackmore, Susan J. & Parker, Jennifer J. (2002). ‘Comparing the Content of Sleep Paralysis and Dream Reports’. ''Dreaming'' 12:1, pp. 45-59.</ref><ref>Spanos, N. P., McNulty, S. A. DuBreuil, S. C. and Pires, M. (1995). ‘The frequency and correlates of sleep paralysis in a university sample’. ''Journal of Research in Personality'' 29:3, pp. 285-305.</ref> The paralysis itself is frequently accompanied by additional [[phenomena (philosophy)|phenomena]]. Typical examples include a feeling of being crushed or [[asphyxia|suffocated]], electric ‘tingles’ or ‘[[vibration]]s’, imagined speech and other noises, the imagined presence of a visible or invisible entity, and sometimes intense [[emotion]]: [[fear]] or [[euphoria]] and [[orgasm|orgasmic]] feelings.<ref>Blackmore, Susan J. & Parker, Jennifer J. (2002). ‘Comparing the Content of Sleep Paralysis and Dream Reports’. ''Dreaming'' 12:1, pp. 45-59.</ref><ref>Cheyne, J. A. (2003). ‘Sleep Paralysis and the Structure of Waking-Nightmare Hallucinations’. ''Dreaming'' 13:3, pp. 163-79.</ref> SP has been proposed as an explanation for at least some [[alien abduction]] experiences.<ref>Blackmore, Susan. (1998) ‘[http://www.csicop.org/si/9805/abduction.html Abduction by Aliens or Sleep Paralysis?]’. ''Skeptical Enquirer'', May/June 1998. (Retrieved 4 July 2008.)</ref> ===Other sensations=== [[Taste|Gustatory]], [[smell|olfactory]] and [[thermoception|thermal]] sensations in hypnagogia have all been reported, as well as [[touch|tactile]] sensations (including those kinds classed as [[paraesthesia]] or [[formication]]). Sometimes there is [[synaesthesia]]; many people report seeing a flash of light or some other visual image in response to a real sound. [[Proprioception|Proprioceptive]] effects may be noticed, with numbness and changes in perceived body size and proportions,<ref>Mavromatis, op. cit., p. 81.</ref> feelings of floating or bobbing, and [[out-of-body experience]]s.<ref>{{cite book | title = Out of Body Experiences | first = Robert | last = Petersen | publisher = Hampton Roads Publishing Company, Inc. | year = 1997 | isbn = 1-57174-057-0}}</ref> Perhaps the most common experience of this kind is the falling sensation, and associated [[hypnic jerk]], encountered by many people, at least occasionally, while drifting off to sleep.<ref>Oswald, Ian (1959). ‘Sudden bodily jerks on falling asleep’. ''Brain'' 82:1, pp. 92-103.</ref> ===Subjective interpretation=== Hypnagogic phenomena may be interpreted as [[visions]], [[prophesies]], [[premonitions]], [[apparitions]] and [[inspiration]] (artistic or divine), depending on the experiencer’s beliefs and those of their culture. ==Cognitive and affective phenomena== ===Receptivity and suggestibility=== [[Thought]] processes on the edge of sleep tend to differ radically from those of ordinary wakefulness. Hypnagogia may involve a “loosening of [[ego]] boundaries ... openness, sensitivity, internalization-subjectification of the physical and mental environment ([[empathy]]) and diffuse-absorbed [[attention]],”<ref>Mavromatis, op. cit., p. 82.</ref> Hypnagogic [[cognition]], in comparison with that of normal, alert wakefulness, is characterised by heightened [[suggestibility]],<ref>Ellis, Havelock (1897). ‘A note on hypnagogic paramnesia’. ''Mind'', New Series, Vol. 6:22, 283-287.</ref> illogic and a fluid association of [[idea]]s. Subjects are more receptive in the hypnagogic state to [[suggestion]] from an experimenter than at other times, and readily incorporate external [[stimulus|stimuli]] into hypnagogic trains of thought and subsequent dreams. This receptivity has a [[physiology|physiological]] parallel; [[EEG]] readings show elevated responsiveness to sound around the onset of sleep.<ref>Mavromatis, op cit., pp. 53-54.</ref> ===Autosymbolism=== [[Herbert Silberer]] described a process he called ''autosymbolism'', whereby hypnagogic hallucinations seem to represent, without [[psychological repression|repression]] or censorship, whatever one is thinking at the time, turning abstract [[idea]]s into a concrete [[mental image|image]], which may be perceived as an apt and succinct representation thereof.<ref>Silberer, Herbert (1909). ‘Bericht ueber eine Methode, gewisse symbolische Halluzinations-Erscheinungen hervorzurufen und zu beobachten. ''Jahrbuch für psychoanalytische Forschungen'' 1:2, pp. 513-525; Eng. Transl. by Rapaport D., 'Report on a method of eliciting and observing certain symbolic hallucination phenomena', in Rapaport’s ''Organization and pathology of thought'', pp. 195-207 (Columbia Univ. Press, New York 1951.).</ref> ===Insight=== This process can even lead to genuine [[insight phenomenology|insight]] into a [[problem solving|problem]], a well known example being the story of [[Kekule|August Kekulé’s]] discovery of the structure of [[benzene]]. Similarly, the teenaged [[Karl Gauss]] obtained an insight during a hypnagogic reverie into how to construct a [[heptadecagon|17-sided polygon]]. Many other [[artist]]s, [[writer]]s, [[scientist]]s and [[inventor]]s – including [[Ludwig van Beethoven|Beethoven]], [[Richard Wagner]], [[Walter Scott]], [[Thomas Edison]] and [[Isaac Newton]] – have credited hypnagogia and related states with enhancing their [[creativity]].<ref>Runco, Mark A. & Pritzker, Stephen R. (1999) ''Encyclopedia of Creativity: a-h'', p. 63-4.</ref> ===Amnesia=== A feature that hypnagogia shares with other stages of sleep is [[amnesia]]. But this is a selective forgetfulness, affecting the [[Hippocampus|hippocampal]] memory system, which is responsible for [[Episodic memory|episodic]] or [[autobiographical memory]], rather than the [[neocortex|neocortical]] memory system, responsible for [[semantic memory]].<ref>Stickgold, R., interviewed 30 October 2000 by Norman Swan for ''Health Report'' on Australia’s [[Radio National]] ([http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s206232.htm transcript]), retrieved 3 July 2008.</ref> It has been suggested that hypnagogia and [[REM sleep]] help in the consolidation of semantic memory,<ref>Stickgold, Robert (1998). ‘Sleep: off-line memory reprocessing’ Trends in Cognitive Sciences 2:12, pp. 484-92.</ref> but the evidence for this has been disputed.<ref>Vertes, Robert E. & Kathleen, Eastman E. (2000) ‘The case against memory consolidation in REM sleep’. Behavioral and Brain ''Behavioural and Brain Sciences'' 23, pp. 867-76.</ref> For example, suppression of [[REM sleep]] due to [[antidepressant]]s and [[lesion]]s to the [[brainstem]] has not been found to produce detrimental effects on cognition.<ref>Vertes, R. (2004) ‘Memory Consolidation in SleepDream or Reality’. ''Neuron'' 44:1, pp. 135-48.</ref> ==Physiology== Physiological studies have tended to concentrate on hypnagogia in the strict sense of spontaneous sleep onset experiences. Such experiences are associated especially with stage 1 of [[NREM]] sleep,<ref>Rechtschaffen, A., & Kales, A. (1968). ''A manual of standardized terminology, techniques and scoring system for sleep stages of human subjects''. Washington, DC: Public Health Service, U.S. Government Printing.</ref> but may also occur with pre-sleep [[alpha wave]]s.<ref>Foulkes, D., & Vogel, G. (1965). ‘Mental activity at sleep onset’. ''Journal of Abnormal Psychology'' 70, 231–43.</ref><ref>Foulkes, D., & Schmidt, M. (1983). ‘Temporal sequence and unit composition in dream reports from different stages of sleep’. ''Sleep'' 6, 265–80.</ref> Davis et al. found short flashes of dreamlike imagery at the onset of sleep to correlate with drop-offs in alpha [[EEG]] activity.<ref>Davis, H., Davis, P. A., Loomis, A. L., Harvey, E. N., & Hobart, G. (1937) ‘Changes in human brain potentials during the onset of sleep’. ''Science'' 86, 448–50.</ref> Hori et al. regard sleep onset hypnagogia as a state distinct from both wakefulness and sleep with unique [[electrophysiology|electrophysiological]], [[behaviour|behavioural]] and [[subjectivity|subjective]] characteristics,<ref>Hori, T., Hayashi, M., & Morikawa, T. (1993). [[EEG topography|Topographical]] EEG changes and hypnagogic experience. In: Ogilvie, R.D., & Harsh, J.R. (Eds.) ''Sleep Onset: Normal and Abnormal Processes'', pp. 237-53.</ref><ref>Vaitl et al. (2005) [http://www.mp.uni-tuebingen.de/mp/fileadmin/user_upload/Kotchoubey/Vaitl-2005-ASC.pdf ‘Psychobiology of altered states of consciousness’]. ''Psychological Bulletin'' 131:1.</ref> while Germaine et al. have demonstrated a resemblance between the EEG [[spectral density|power spectra]] of spontaneously occurring hypnagogic images, on the one hand, and those of both [[REM sleep]] and relaxed wakefulness, on the other.<ref>Nielsen, T., Germain, A., & Ouellet, L. (1995). ‘Atonia-signalled hypnagogic imagery: Comparative EEG mapping of sleep onset transitions, REM sleep, and wakefulness’. ''Sleep Research'' 24, p. 133.</ref> To identify more precisely the nature of the EEG state which accompanies imagery in the transition from wakefulness to sleep, Hori et al. proposed a scheme of 9 EEG stages defined by varying proportions of [[alpha wave|alpha]] (stages 1-3), suppressed waves of less than 20μV (stage 4), [[theta wave|theta]] ripples (stage 5), proportions of [[sawtooth]] waves (stages 6-7), and presence of [[sleep spindle|spindles]] (stages 8-9).<ref>Hori, T., Hayashi, M., & Morikawa, T. (1993). Topographical EEG changes and hypnagogic experience. In: Ogilvie, R.D., & Harsh, J.R. (Eds.) ''Sleep Onset: Normal and Abnormal Processes'', pp. 237-53.</ref> Germaine and Nielsen found spontaneous hypnagogic imagery to occur mainly during Hori sleep onset stages 4 (EEG flattening) and 5 (theta ripples).<ref>Germaine, A. & Nielsen T. A. (1997). ‘Distribution of spontaneous hypnagogic images across Hori's EEG stages of sleep onset’. ''Sleep Research'' 26, p. 243.</ref> The ‘covert-rapid-eye-movement’ hypothesis proposes that hidden elements of [[REM sleep]] emerge during the wakefulness-sleep transition stage.<ref>Robert Bodizs, Melinda Sverteczki, Alpar Sandor Lazar and Peter Halasz (2005). Human parahippocampal activity: non-REM and REM elements in wake-sleep transition. ''Brain Research Bulletin'' 65:2, pp. 169-76.</ref> Support for this comes from Bódicz et al., who note a greater similarity between WST (wakefulness-sleep transition) EEG and REM sleep EEG than between the former and stage 2 sleep.<ref>{{cite web |title=Róbert Bódizs, Melinda Sverteczki and Eszter Mészáros, ''Wakefulness-sleep transition: Emerging electroencephalographic similarities with the rapid eye movement phase'',| url=http://www.sciencedirect.com/science/article/B6SYT-4RCN8CP-1/2/eee96a80f27593096fdace6bb9fce440|accessdate=2008-03-31}}</ref> [[Respiratory]] pattern changes have also been noted in the hypnagogic state, in addition to a lowered rate of [[frontalis muscle]] activity.<ref>Schacter, Daniel L. (1976). 'The hypnagogic state: A critical review of the literature'. ''Psychological Bulletin'', Vol 83:3, pp. 452-481.</ref> ==Daydreaming and waking reveries== [[Microsleep]] (short episodes of immediate sleep onset) may intrude into wakefulness. at any time in the wakefulness-sleep cycle, due to [[sleep deprivation]] and other conditions,<ref>Oswald, I. (1962). ''Sleeping and waking: Physiology and psychology''. Amsterdam: Elsevier.</ref> resulting in impaired cognition, amnesia.<ref>Vaitl et al. (2005) ‘[http://www.mp.uni-tuebingen.de/mp/fileadmin/user_upload/Kotchoubey/Vaitl-2005-ASC.pdf Psychobiology of altered states of consciousness]’. ''Psychological Bulletin'' 131:1.</ref> Gurstelle and Oliveira distinguish a state which they call ''daytime parahypnagogia'' (DPH), the spontaneous intrusion of a flash image or dreamlike thought or insight into one’s waking consciousness. DHP is typically encountered when one is “[[fatigue (medical)|tired]], [[boredom|bored]], suffering from attention fatigue, and/or engaged in a passive activity.” The exact nature of the episode may be forgotten even though the individual remembers having had such an experience.<ref>Gurstelle, E. B. & Oliveira, J. L. (2004) ‘Daytime parahypnagogia: a state of consciousness that occurs when we almost fall asleep’. ''Medical Hypotheses'' 62:2, pp. 166-8.</ref> Gustelle and Oliveira define DPH as “dissociative, [[trance]]-like, [...] but, unlike a [[daydream]], [...] not self-directed” – however, daydreams and waking reveries are often characterised as “passive,” “effortless,”<ref>Runco, Mark A. & Pritzker, Stephen R. (1999) ''Encyclopedia of Creativity: a-h'', p. 64.</ref> and “spontaneous,” <ref>Vaitl et al. (2005) ‘[http://www.mp.uni-tuebingen.de/mp/fileadmin/user_upload/Kotchoubey/Vaitl-2005-ASC.pdf Psychobiology of altered states of consciousness]’. ''Psychological Bulletin'' 131:1.</ref> while hypnagogia itself can sometimes be influenced by a form of [[autosuggestion]], or “passive concentration,”<ref>Mavromatis, op. cit., p. 73, etc.</ref> so these sorts of episode may in fact constitute a continuum between directed fantasy and the more spontaneous varieties of hypnagogia. Others have emphasised the connections between fantasy, daydreaming, dreams and hypnosis.<ref>Singer, Jerome L. & Pope, Kenneth, S. (1981) ‘Daydreaming and imagery skills as predisposing capacities for self-hypnosis’. ''International Journal of Clinical and Experimental Hypnosis'', 29:3, pp. 271-81.</ref> ==Investigative methodology== Self-observation (spontaneous or systematic) was the primary tool of the early researchers. In the late 20th and early 21st centuries, this has been joined by questionnaire surveys and experimental studies. All three methods have their disadvantages as well as points to recommend them.<ref>Mavromatis, op. cit., p. 286.</ref> Naturally, amnesia contributes to the difficulty of studying hypnagogia, as does the typically fleeting nature of hypnagogic experiences. These problems have been tackled by experimenters in a number of ways, including voluntary or induced interruptions,<ref>Germaine, A. & Nielsen T. A. (1997). ‘Distribution of spontaneous hypnagogic images across Hori's EEG stages of sleep onset’. ''Sleep Research'' 26, p. 243.</ref> sleep manipulation,<ref>{{ cite book | title = Consciousness: An Introduction | first = Susan | last = Blackmore | publisher = London: Hodder & Stoughton | year = 2003 | isbn = 0-340-80909-4 }} p. 314.</ref> the use of techniques to “hover on the edge of sleep” thereby extending the duration of the hypnagogic state,<ref>Blackmore 2003, op. cit. p. 312.</ref> and training in the art of introspection to heighten the subject’s powers of observation and attention.<ref>Blackmore 2003, op. cit., p. 312.</ref> Techniques for extending hypnagogia range from informal ones (e.g. the subject holds up one of their arms as they go to sleep, so as to be awakened when it falls),<ref>Blackmore 2003, op. cit. p. 312.</ref> to the use of biofeedback devices to induce a ‘[[theta waves|theta]]’ state, characterised by relaxation and theta EEG activity.<ref>Mavromatis, op. cit., p. 93.</ref> Another method is to induce a state said to be subjectively similar to sleep onset in a [[Ganzfeld effect|Ganzfeld]] setting, a form of [[sensory deprivation]]. But the assumption of identity between the two states may be unfounded. The average [[EEG]] spectrum in Ganzfeld is more similar to that of the relaxed waking state than to that of sleep onset.<ref>Wackermann, Jiri, Pütz, Peter, Büchi, Simone, Strauch, Inge & Lehmann, Dietrich (2000). ‘A comparison of Ganzfeld and hypnagogic state in terms of electrophysiological measures and subjective experience’. ''Proceedings of the 43rd Annual Convention of the Parapsychological Association'', pp. 302-15.</ref> Wackerman et al. conclude that “the Ganzfeld imagery, although subjectively very similar to that at sleep onset, should not be labeled as ‘hypnagogic’. Perhaps a broader category of ‘hypnagoid experience’ should be considered, covering true hypnagogic imagery as well as subjectively similar imagery produced in other states.”<ref>Wackermann et al., op. cit.</ref> == Artistic and cultural references == *[[Kitchens of Distinction]] recorded a song entitled "Hypnogogic" for their 1990 album ''Strange Free World''. *The album ''The Always Open Mouth'', by the band [[Fear Before the March of Flames]], features the song "Drowning the Old Hag" which describes singer David Marion's experiences with hypnagogia. *In ''[[The Green Man]]'' by [[Kingsley Amis]] the narrator suffers from [[sleep paralysis]] and has [[hypnagogic hallucinations]]. * In ''[[Disgrace]]'' by [[J.M. Coetzee]], the main character David Lurie refers to his own hypnagogic experience as he recalls his former lovers. * The musician Adem refers to hypnogogic shapes in his song "You and Moon", taken from his 2006 album "Love and Other Planets". *The electronica musician L. Pierre ([[Aidan Moffat]] formerly of Arab Strap) titled his 2005 album ''Hypnogogia''. *An artist named Maxwell Lewis? has entitled an album "Awake as a Hypnagog," which is based on a lucid dream he claims to have had. *The song "[[A Better Son/Daughter]]" by [[Rilo Kiley]] begins with an account of [[hypnopompic]] [[sleep paralysis]]. *The band [[Host Echo]] in their 2005 debut album "Be Water" featured a song titled "Hypnogogic" *In [[Herman Melville]]'s novel, ''[[Moby-Dick]]'', a hypnogogic hallucination is described in chapter 4, "The Counterpane" * [[Current 93]] published an album called [[Hypnagogue/Hypnagogue II]] in 2005 *Noise rock band [[The Locust]] in their 2005 EP "Safety Second, Body Last" mention hypnagogia in their lyrics. *In the 1991 film [[Hook (film)|Hook]] Tinkerbell refers to Neverland as being "the place between waking and dreaming." ==Further reading== * Leaning, F.E. (1925). An introductory study of hypnagogic phenomena. ''Proceedings of the Society for Psychical Research'', '''35''', 289-409. * Mavromatis, A. (1987). ''Hypnagogia: the Unique State of Consciousness Between Wakefulness and Sleep''. London: Routledge and Kegan Paul. *{{Cite book|chapter=The Hypnagogic|title=The Head Trip: Adventures on the Wheel of Consciousness|year=2007|isbn=978-0679314080|first=Jeff|last=Warren}} ==References== {{reflist|2}} ==See also== *[[False awakening]] *[[Hag#Hag in folklore|Hag in folklore]] *[[Hypnic jerk]] *[[Lucid dream]] *[[Nightmare]] *[[Segmented sleep]] *[[Sleep disorder]] *[[Sleep paralysis]] *[[Tetris effect]] *[[Threshold consciousness]] *[[Hypnopompic]] ==External links== *"[http://bjp.rcpsych.org/cgi/content/abstract/169/4/459 Hypnagogic and hypnopompic hallucinations: pathological phenomena?]" article in the ''[[British Journal of Psychiatry]]'' *[http://www.forteantimes.com/features/articles/227/hypnagogia.html Gary Lachman on Hypnagogia] {{SleepSeries2}} [[Category:Sleep disorders]] [[Category:Sleep physiology]] [[Category:Lucid dreams]] [[de:Hypnagogie]] [[el:Υπναγωγία]] [[es:Alucinación hipnogógica]] [[fr:Hypnagogie]] [[it:Illusione ipnagogica]] [[nl:Hypnagogie]] [[pl:Hipnagogia]] [[sv:Hypnagogi]] [[tr:Hypnagogia]]