Hypnagogia

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This article is about the psychological state. For the musical genre, see Hypnagogic pop.
"Waking dream" redirects here. Not to be confused with
daydreaming
.

Hypnagogia is the transitional state from wakefulness to sleep, also defined as the waning state of consciousness during the onset of sleep. Its opposite state is described as hypnopompia – the transitional state from sleep into wakefulness. Mental phenomena that may occur during this "threshold consciousness" phase include hypnagogic hallucinations, lucid dreaming, and sleep paralysis.

Etymology

In 1848,

Frederic Myers coined the term "hypnopompic," with its word-ending originating from the Greek word "pompos," meaning "sender."[1]

Definitions

The word hypnagogia is sometimes used in a restricted

experience
may occur in both as people drift in and out of sleep.

Other terms for hypnagogia, in one or both senses, that have been proposed include "presomnal" or "anthypnic sensations", "visions of half-sleep", "oneiragogic images" and "phantasmata",[3] "the borderland of sleep", "praedormitium",[4] "borderland state", "half-dream state", "pre-dream condition",[5] "sleep onset dreams",[6] "dreamlets",[7] and "wakefulness-sleep transition" (WST).[8]

Threshold consciousness (commonly called "half-asleep" or "half-awake", or "mind awake body asleep") describes the same mental state of someone who is moving towards sleep or wakefulness but has not yet completed the transition. Such transitions are usually brief but can be extended by sleep disturbance or deliberate induction, for example during meditation.[citation needed]

Signs and symptoms

Transition to and from sleep may be attended by a wide variety of sensory experiences. These can occur in any modality, individually or combined, and range from the vague and barely perceptible to vivid hallucinations.[9]

Sights

Among the more commonly reported,

perspective). Imagery representing movement through tunnels of light is also reported. 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,[12] although others understand the state rather as a gradual transition from hypnagogia to fragmentary dreams,[13] i.e., from simple Eigenlicht to whole 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
.

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 drowsy, a tendency dubbed the Tetris effect. This effect has even been observed in amnesiacs who otherwise have no memory of the original activity.[14] When the activity involves moving objects, as in the video game Tetris, the corresponding hypnagogic images tend to be perceived as moving. The Tetris effect is not confined to visual imagery but can manifest in other modalities. For example, Robert Stickgold recounts having experienced the touch of rocks while falling asleep after mountain climbing.[6] This can also occur to people who have travelled on a small boat in rough seas or have been swimming through waves, shortly before going to bed, and they feel the waves as they drift to sleep, or people who have spent the day skiing who continue to "feel snow" under their feet. People who have spent considerable time jumping on a trampoline will find that they can feel the up-and-down motion before they go to sleep. New employees working stressful and demanding jobs often report feeling the experience of performing work-related tasks in this period before sleep.[citation needed]

Sounds

Hypnagogic hallucinations are often auditory or have an auditory component. Like the visuals, hypnagogic sounds vary in intensity from faint impressions to loud noises, like knocking and crashes and bangs (

inner voice", or as the voices of others: familiar people or strangers. More rarely, poetry or music is heard.[15]

Other sensations

Proprioceptive effects may be noticed, with numbness and changes in perceived body size and proportions,[15] feelings of floating or bobbing as if their bed were a boat, and out-of-body experiences.[16] 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.[17]

Cognitive and affective phenomena

EEG readings show elevated responsiveness to sound around the onset of sleep.[20]

repression or censorship, whatever one is thinking at the time, turning abstract ideas into a concrete image, which may be perceived as an apt and succinct representation thereof.[21]

The hypnagogic state can provide

ourobouros.[22] Many other artists, writers, scientists and inventors – including Beethoven, Richard Wagner, Walter Scott, Salvador Dalí, Thomas Edison, Nikola Tesla and Isaac Newton – have credited hypnagogia and related states with enhancing their creativity.[23] A 2001 study by Harvard psychologist Deirdre Barrett found that, while problems can also be solved in full-blown dreams from later stages of sleep, hypnagogia was especially likely to solve problems which benefit from hallucinatory images being critically examined while still before the eyes.[24]

A feature that hypnagogia shares with other stages of sleep is

REM sleep help in the consolidation of semantic memory,[25] but the evidence for this has been disputed.[26] In particular, suppression of REM sleep due to antidepressants and lesions to the brainstem has not been found to produce detrimental effects on cognition.[27]

Hypnagogic phenomena may be interpreted as

premonitions, apparitions and inspiration (artistic or divine
), depending on the experiencers' beliefs and those of their culture.

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

REM sleep and relaxed wakefulness, on the other.[32]

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 (stages 1–3), suppressed waves of less than 20μV (stage 4), theta ripples (stage 5), proportions of sawtooth waves (stages 6–7), and presence of spindles (stages 8–9).[10] Germaine and Nielsen found spontaneous hypnagogic imagery to occur mainly during Hori sleep onset stages 4 (EEG flattening) and 5 (theta ripples).[11]

The "covert-rapid-eye-movement" hypothesis proposes that hidden elements of

REM sleep emerge during the wakefulness-sleep transition stage.[33]
Support for this comes from Bódicz et al., who notes a greater similarity between WST (wakefulness-sleep transition) EEG and REM sleep EEG than between the former and stage 2 sleep.[8]

Respiratory pattern changes have also been noted in the hypnagogic state, in addition to a lowered rate of frontalis muscle activity.[7]

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,[34] resulting in impaired cognition and even amnesia.[12]

In his book, Zen and the Brain, James H. Austin cites speculation that regular meditation develops a specialized skill of "freezing the hypnagogic process at later and later stages" of the onset of sleep, initially in the alpha wave stage and later in theta.[35]

History

Early references to hypnagogia can be found in the writings of

Swedenborg.[36] Romanticism brought a renewed interest in the subjective experience of the edges of sleep.[37] 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."[4]

In Charles Dickens's Oliver Twist there is a pair of episodes, one that portrays the title character experiencing a hypnopompic state, which precedes the following episode, which describes him in a hypnagogic state:

There is a kind of sleep that steals upon us sometimes, which, while it holds the body prisoner, does not free the mind from a sense of things about it, and enable it to ramble at its pleasure. … It is an undoubted fact, that although our senses of touch and sight be for the time dead, yet our sleeping thoughts, and the visionary scenes that pass before us, will be influenced and materially influenced, by the mere silent presence of some external object; which may not have been near us when we closed our eyes: and of whose vicinity we have had no waking consciousness.”[38][39]

Serious scientific inquiry began in the 19th century with Johannes Peter Müller, Jules Baillarger, and Alfred Maury, and continued into the 20th century with Leroy.[40]

Francis Galton in his The Visions of Sane Persons (1881), wrote:

[B]efore I thought of carefully trying, I should have emphatically declared that my field of view in the dark was essentially of a uniform black, subject to an occasional light-purple cloudiness and other small variations. Now, however, after habituating myself to examine it with the same sort of strain that one tries to decipher a sign-post in the dark, I have found out that this is by no means the case, but that a kaleidoscopic change of patterns and forms is continually going on, but they are too fugitive and elaborate for me to draw with any approach to truth.

Maria Mikhaĭlovna Manaseina wrote “that for these phenomena to attract attention a certain power of observation is required; that is why they are chiefly found in intelligent persons.” Manaseina also noted that children are more likely to take interest in them: “[M]any children are accustomed to press their heads into the pillow and adopt an attitude of expectant attention towards the visions that then begin to form…"[41]

Havelock Ellis later recalled such a childhood interest in these visions:

I should myself be inclined to deny that I had ever had any such visionary faculty [for hypnagogic hallucination] if it were not that I can recall one occasion of its presence, at about the age of seven, when sleeping with a cousin of the same age; we amused ourselves by burying our heads in the pillows and watching a connected series of pictures which we were both alike able to see, each announcing any change in the picture as soon as it took place.[42]

The advent of

altered states of consciousness playing an important role in the emerging multidisciplinary study of consciousness.[12]
[43] 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".[44]

Important reviews of the scientific literature have been made by Leaning,[45] Schacter,[7] Richardson and Mavromatis.[3]

Research

Self-observation (spontaneous or systematic) was the primary tool of the early researchers. Since the late 20th century, this has been joined by questionnaire surveys and experimental studies. All three methods have their disadvantages as well as points to recommend them.[46]

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 several ways, including voluntary or induced interruptions,[11] sleep manipulation,[47] the use of techniques to "hover on the edge of sleep" thereby extending the duration of the hypnagogic state,[47] and training in the art of introspection to heighten the subject's powers of observation and attention.[47]

Techniques for extending hypnagogia range from informal (e.g. the subject holds up one of their arms as they go to sleep, to be awakened when it falls),

EEG activity.[48]

Another method is to induce a state said to be subjectively similar to sleep onset in a 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.[49] Wackerman et al. conclude that "the Ganzfeld imagery, although subjectively very similar to that at sleep onset, should not be labelled as 'hypnagogic'. Perhaps a broader category of 'hypnagogic experience' should be considered, covering true hypnagogic imagery as well as subjectively similar imagery produced in other states."[49]

See also

  • False awakening – Vivid and convincing dream about awakening from sleep
  • Nightmare – Unpleasant dream
  • Night terror – Sleep disorder causing feelings of panic or dread
  • Biphasic and polyphasic sleep
     – Sleep pattern with more than one period of sleep in a 24-hour period
  • Sleep disorder – Medical disorder of a person's sleep patterns
  • Yoga nidra – State of consciousness between waking and sleeping induced by a guided meditation
  • Dream yoga – Tibetan meditation practice
  • Dreamachine – Stroboscopic light art designed by Ian Somnerville & Brion Gysin

References

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  4. ^ a b Mavromatis (1987), p. 4
  5. ^ Lachman, Gary (2002). 'Hypnagogia'. Fortean Times.
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  19. ^ Ellis, Havelock (1897). 'A note on hypnagogic paramnesia'. Mind, New Series, Vol. 6:22, 283–287.
  20. ^ Mavromatis (1987), pp. 53–54
  21. ^ Silberer, Herbert (1909). 'Bericht Ueber eine Methode, gewisse symbolische Hallucinations-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.).
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  38. ^ [1] Edgecomb, Rodney Stenning. "The Oneiric Vision of "Oliver Twist". Dickens Quarterly. Vol. 31, No. 2, June 2014. p. 98-102
  39. ^ Charles Dickens, Oliver Twist, Chapter 34
  40. ^ Leroy, E.B. (1933). Les visions du demi-sommeil. Paris: Alcan.
  41. ^ Maria Mikhaĭlovna Manaseina Sleep, its Physiology, Pathology, Hygiene, and Psychology (1897)
  42. ^ Havelock Ellis The World of Dreams (1916)
  43. ^ Blackmore (2003)
  44. ^ Mavromatis (1987), p. xiii
  45. ^ Leaning F.E. (1925). "An introductory study of hypnagogic phenomena". Proceedings of the Society for Psychical Research. 35: 289–409.
  46. ^ Mavromatis (1987), p. 286
  47. ^ a b c d Blackmore (2003), p. 314
  48. ^ Mavromatis (1987), p. 93
  49. ^ a b 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.

Bibliography

Further reading

External links

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