Hypnagogia
Encyclopedia
Hypnagogia is the transitional state between wakefulness and sleep
(i.e., the onset of sleep
), originally coined in adjectival form as "hypnagogic" by Alfred Maury
.
The equivalent transition to wakefulness is termed the hypnopompic state
. Mental phenomena that occur during this "threshold consciousness" phase include lucid dreaming
, hallucinations, out of body experiences and sleep paralysis
. The collective noun "Hypnagogia" was coined by Dr Andreas Mavromatis in his 1983 thesis (Brunel University) which was later published by Routledge (hardback 1987, paperback 1991) under the title "Hypnagogia" the Unique State of Consciousness Between Wakefulness and Sleep and reprinted in a new paperback edition in 2010 by Thyrsos Press. The term "hypnagogia" is employed by Dr Mavromatis to include both sleep onset and the transition from sleep to wakefulness; he retains, however, the adjectives "hypnagogic" and "hypnopompic" for the identification of specific experiences.
to refer to the onset of sleep, and contrasted with hypnopompia, Frederic Myers
's term for waking up. 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. Indeed, it is not always possible in practice to assign a particular episode of any given phenomenon to one or the other, given that the same kinds of 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", "the borderland of sleep", "praedormitium", the "borderland state", "half-dream state", "pre-dream condition", "sleep onset dreams", dreamlets, and "wakefulness-sleep transition" state (WST).
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.
, Iamblichus, Cardano, Simon Forman
and Swedenborg. Romanticism
brought a renewed interest in the subjective experience of the edges of sleep. 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."
Serious scientific enquiry began in the 19th century with Johannes Peter Müller
, Jules Baillarger
and Alfred Maury
, and continued into the twentieth century with Leroy.
The advent of electroencephalography
(EEG) has supplemented the introspective methods of these early researchers with physiological data. The search for neural correlates for hypnagogic imagery began with Davis et al. in the 1930s, and continues with increasing sophistication to this day. While the dominance of the behaviorist 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 ASCs
playing an important role in the emerging multidisciplinary study of consciousness
. 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."
Important reviews of the scientific literature have been made by Leaning, Schacter
, Richardson and Mavromatis.
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 hallucination
s.
(representational) images
. They may be monochromatic or richly color
ed, still or moving, flat or three-dimensional (offering an impression of 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, although others understand the state rather as a gradual transition from hypnagogia to fragmentary dreams, i.e., from simple "eigenlicht
" to whole imagined
scenes. Hypnagogia can be induced with a Dreamachine
, which uses light pulsing at a frequency close to that of alpha waves to create this effect. Descriptions of exceptionally vivid and elaborate hypnagogic visuals can be found in the work of Marie-Jean-Léon, Marquis d'Hervey de Saint Denys
.
, a tendency dubbed the Tetris effect
. This effect has even been observed in amnesia
cs who otherwise have no memory
of the original activity. 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 also. For example, Robert Stickgold
recounts having experienced the touch of rocks while falling asleep after mountain climbing. This can also occur to people who have traveled 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, also 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. Many chess
players report the phenomenon of seeing the chess board and pieces during this state. New employees working stressful and demanding jobs often report doing work-related tasks in this period before sleep. This is very common amongst new waiters or waitresses in busy restaurants where they report having "Server Dreams" and restlessly wait tables in this state of mind, sometimes jolting them fully awake or preventing them from transitioning into actual sleep.
). People may imagine their own name called or a doorbell ringing. Snatches of imagined speech
are common. While typically 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 word play
, neologisms and made-up name
s. Hypnagogic speech may manifest as the subject's own "inner voice
", or as the voices of others: familiar people or strangers. More rarely, poetry
or music
is heard.
(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. Sleep paralysis is reportedly very frequent among narcoleptics. It occurs frequently in about 6% of the rest of the population, and occurs occasionally in 60%. In surveys from Canada, China, England, Japan and Nigeria, 20 to 60% of individuals reported having experienced SP at least once in their lifetime. The paralysis itself is frequently accompanied by additional phenomena. Typical examples include a feeling of being crushed or 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
ic feelings. SP has been proposed as an explanation for at least some alien abduction experiences and shadow people
hauntings.
sensations in hypnagogia have all been reported, as well as tactile sensations (including those kinds classed as paresthesia
or formication
). Sometimes there is synesthesia
; many people report seeing a flash of light or some other visual image in response to a real sound. Proprioceptive effects may be noticed, with numbness and changes in perceived body size and proportions, feelings of floating or bobbing, and out-of-body experience
s. 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.
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
." Hypnagogic cognition
, in comparison with that of normal, alert wakefulness, is characterized by heightened suggestibility
, 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 stimuli
into hypnagogic trains of thought and subsequent dreams. This receptivity has a physiological parallel; EEG
readings show elevated responsiveness to sound around the onset of sleep.
Herbert Silberer
described a process he called autosymbolism, whereby hypnagogic hallucinations seem to represent, without repression
or censorship, whatever one is thinking at the time, turning abstract idea
s into a concrete image
, which may be perceived as an apt and succinct representation thereof.
The hypnagogic state can provide insight
into a problem
, the best known example being August Kekulé’s realization that the structure of benzene
was a closed ring after dozing in front of a fire and seeing molecules forming into snakes, one of which grabbed its tail in its mouth. Many other artist
s, writer
s, scientist
s and inventors—including Beethoven
, Richard Wagner
, Walter Scott
, Salvador Dalí
, Thomas Edison
and Isaac Newton
—have credited hypnagogia and related states with enhancing their creativity
. 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.
A feature that hypnagogia shares with other stages of sleep is amnesia
. But this is a selective forgetfulness, affecting the hippocampal memory system, which is responsible for episodic
or autobiographical memory
, rather than the neocortical memory system, responsible for semantic memory
. It has been suggested that hypnagogia and REM sleep help in the consolidation of semantic memory, but the evidence for this has been disputed. 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.
Hypnagogic phenomena may be interpreted as visions
, prophecies, premonitions, apparitions
and inspiration (artistic
or divine
), depending on the experiencers' beliefs and those of their culture.
s. Davis et al. found short flashes of dreamlike imagery at the onset of sleep to correlate with drop-offs in alpha EEG
activity. Hori et al. regard sleep onset hypnagogia as a state distinct from both wakefulness and sleep with unique electrophysiological, behavior
al and subjective
characteristics, while Germaine et al. have demonstrated a resemblance between the EEG power spectra
of spontaneously occurring hypnagogic images, on the one hand, and those of both REM sleep and relaxed wakefulness, on the other.
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). Germaine and Nielsen found spontaneous hypnagogic imagery to occur mainly during Hori sleep onset stages 4 (EEG flattening) and 5 (theta ripples).
The "covert-rapid-eye-movement" hypothesis proposes that hidden elements of REM sleep emerge during the wakefulness-sleep transition stage. 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.
Respiratory pattern changes have also been noted in the hypnagogic state, in addition to a lowered rate of frontalis muscle
activity.
(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, resulting in impaired cognition, amnesia.
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. DPH is typically encountered when one is "tired, 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. 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", and "spontaneous", while hypnagogia itself can sometimes be influenced by a form of autosuggestion
, or "passive concentration", so these sorts of episode may in fact constitute a continuum between directed fantasy and the more spontaneous varieties of hypnagogia. Others have emphasized the connections between fantasy, daydreaming, dreams and hypnosis.
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.
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, sleep manipulation, the use of techniques to "hover on the edge of sleep" thereby extending the duration of the hypnagogic state, and training in the art of introspection to heighten the subject's powers of observation and attention.
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), to the use of biofeedback devices to induce a "theta" state, characterized by relaxation and theta EEG activity. The theta state is produced naturally the most when we are dreaming. It has also been linked to paranormal activities, and Rick Straussman has argued that it triggers the release of DMT from the pineal gland, causing a dreaming state.
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. 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."
Sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...
(i.e., the onset of sleep
Sleep onset
Sleep onset is the transition from wakefulness into sleep. Sleep onset usually transmits into non-rapid eye movement sleep but in certain situations like narcolepsy, it is possible to transmit from wakefulness directly into rapid eye movement sleep...
), originally coined in adjectival form as "hypnagogic" by Alfred Maury
Louis Ferdinand Alfred Maury
Louis Ferdinand Alfred Maury , was a French scholar, born at Meaux.In 1836, having completed his education, he entered the Bibliothèque Nationale, and afterwards the Bibliothèque de l'Institut , where he devoted himself to the study of archaeology, ancient and modern languages, medicine and...
.
The equivalent transition to wakefulness is termed the hypnopompic state
Hypnopompic
A hypnopompic state is the state of consciousness leading out of sleep, a term coined by the psychical researcher Frederic Myers. Its twin is the hypnagogic state at sleep onset; though often conflated, the two states are not identical...
. Mental phenomena that occur during this "threshold consciousness" phase include lucid dreaming
Lucid dreaming
A lucid dream is a dream in which one is aware that one is dreaming. The term was coined by the Dutch psychiatrist and writer Frederik van Eeden . In a lucid dream, the dreamer can actively participate in and manipulate imaginary experiences in the dream environment. Lucid dreams can seem real and...
, hallucinations, out of body experiences and sleep paralysis
Sleep paralysis
Sleep paralysis is paralysis associated with sleep that may occur in healthy persons or may be associated with narcolepsy, cataplexy, and hypnagogic hallucinations. The pathophysiology of this condition is closely related to the normal hypotonia that occurs during REM sleep. When considered to be a...
. The collective noun "Hypnagogia" was coined by Dr Andreas Mavromatis in his 1983 thesis (Brunel University) which was later published by Routledge (hardback 1987, paperback 1991) under the title "Hypnagogia" the Unique State of Consciousness Between Wakefulness and Sleep and reprinted in a new paperback edition in 2010 by Thyrsos Press. The term "hypnagogia" is employed by Dr Mavromatis to include both sleep onset and the transition from sleep to wakefulness; he retains, however, the adjectives "hypnagogic" and "hypnopompic" for the identification of specific experiences.
Definitions and synonyms
Sometimes the word hypnagogia is used in a restricted senseWord sense
In linguistics, a word sense is one of the meanings of a word.For example a dictionary may have over 50 different meanings of the word , each of these having a different meaning based on the context of the word usage in a sentence...
to refer to the onset of sleep, and contrasted with hypnopompia, Frederic Myers
Frederic William Henry Myers
Frederic William Henry Myers was a classical scholar, poet, philosopher, and past president of the Society for Psychical Research.-Early life:...
's term for waking up. However, hypnagogia is also regularly employed in a more general sense that covers both falling asleep and waking up, and Havelock Ellis
Havelock Ellis
Henry Havelock Ellis, known as Havelock Ellis , was a British physician and psychologist, writer, and social reformer who studied human sexuality. He was co-author of the first medical textbook in English on homosexuality in 1897, and also published works on a variety of sexual practices and...
questioned the need for separate terms. Indeed, it is not always possible in practice to assign a particular episode of any given phenomenon to one or the other, given that the same kinds of 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", "the borderland of sleep", "praedormitium", the "borderland state", "half-dream state", "pre-dream condition", "sleep onset dreams", dreamlets, and "wakefulness-sleep transition" state (WST).
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.
History
Early references to hypnagogia are to be found in the writings of AristotleAristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
, Iamblichus, Cardano, Simon Forman
Simon Forman
Simon Forman was arguably the most popular Elizabethan astrologer, occultist and herbalist active in London during the reigns of Queen Elizabeth I and James I of England. His reputation, however, was severely tarnished after his death when he was implicated in the plot to kill Sir Thomas Overbury...
and Swedenborg. Romanticism
Romanticism
Romanticism was an artistic, literary and intellectual movement that originated in the second half of the 18th century in Europe, and gained strength in reaction to the Industrial Revolution...
brought a renewed interest in the subjective experience of the edges of sleep. In more recent centuries, many authors have referred to the state; Edgar Allan Poe
Edgar Allan Poe
Edgar Allan Poe was an American author, poet, editor and literary critic, considered part of the American Romantic Movement. Best known for his tales of mystery and the macabre, Poe was one of the earliest American practitioners of the short story and is considered the inventor of the detective...
, for example, wrote of the "fancies" he experienced "only when I am on the brink of sleep, with the consciousness that I am so."
Serious scientific enquiry began in the 19th century with Johannes Peter Müller
Johannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
, Jules Baillarger
Jules Baillarger
Jules Baillarger, full name Jules Gabriel François Baillarger was a French neurologist and psychiatrist who was born in Montbazon....
and Alfred Maury
Louis Ferdinand Alfred Maury
Louis Ferdinand Alfred Maury , was a French scholar, born at Meaux.In 1836, having completed his education, he entered the Bibliothèque Nationale, and afterwards the Bibliothèque de l'Institut , where he devoted himself to the study of archaeology, ancient and modern languages, medicine and...
, and continued into the twentieth century with Leroy.
The advent of electroencephalography
Electroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
(EEG) has supplemented the introspective methods of these early researchers with physiological data. The search for neural correlates for hypnagogic imagery began with Davis et al. in the 1930s, and continues with increasing sophistication to this day. While the dominance of the behaviorist 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 ASCs
Altered state of consciousness
An altered state of consciousness , also named altered state of mind, is any condition which is significantly different from a normal waking beta wave state. The expression was used as early as 1966 by Arnold M. Ludwig and brought into common usage from 1969 by Charles Tart: it describes induced...
playing an important role in the emerging multidisciplinary study of consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
. 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."
Important reviews of the scientific literature have been made by Leaning, Schacter
Daniel Schacter
Daniel Lawrence Schacter is an American psychologist. He is a Professor of Psychology at Harvard University. His research has focused on psychological and biological aspects of human memory and amnesia, with a particular emphasis on the distinction between conscious and nonconscious forms of...
, Richardson and Mavromatis.
Sensory phenomena
Transition to and from sleepSleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...
may be attended by a wide variety of sensory
Sense
Senses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...
experiences. These can occur in any modality, individually or combined, and range from the vague and barely perceptible to vivid hallucination
Hallucination
A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
s.
Sights
Among the more commonly reported, and more thoroughly researched, sensory features of hypnagogia are phosphenes which can manifest as seemingly random speckles, lines or geometrical patterns, including form constants, or as figurativeFigurative art
Figurative art, sometimes written as figurativism, describes artwork—particularly paintings and sculptures—which are clearly derived from real object sources, and are therefore by definition representational.-Definition:...
(representational) images
Mental image
A mental image is an experience that, on most occasions, significantly resembles the experience of perceiving some object, event, or scene, but occurs when the relevant object, event, or scene is not actually present to the senses...
. They may be monochromatic or richly color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
ed, still or moving, flat or three-dimensional (offering an impression of perspective
Perspective (visual)
Perspective, in context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects...
). 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
Narrative
A narrative is a constructive format that describes a sequence of non-fictional or fictional events. The word derives from the Latin verb narrare, "to recount", and is related to the adjective gnarus, "knowing" or "skilled"...
content, although others understand the state rather as a gradual transition from hypnagogia to fragmentary dreams, i.e., from simple "eigenlicht
Eigengrau
Eigengrau , also called Eigenlicht , dark light, or brain gray, is the color seen by the eye in perfect darkness...
" to whole imagined
Imagination
Imagination, also called the faculty of imagining, is the ability of forming mental images, sensations and concepts, in a moment when they are not perceived through sight, hearing or other senses...
scenes. Hypnagogia can be induced with a Dreamachine
Dreamachine
The dreamachine is a stroboscopic flicker device that produces visual stimuli. Artist Brion Gysin and William S. Burroughs's "systems adviser" Ian Sommerville created the dreamachine after reading William Grey Walter's book, The Living Brain.-History:In the dreamachine's original form, a...
, which uses light pulsing at a frequency close to that of alpha waves to create this effect. Descriptions of exceptionally vivid and elaborate hypnagogic visuals can be found in the work of Marie-Jean-Léon, Marquis d'Hervey de Saint Denys
Marie-Jean-Léon, Marquis d'Hervey de Saint Denys
Marie-Jean-Léon Lecoq, Baron d'Hervey de Juchereau, Marquis d'Hervey de Saint-Denys , was a French sinologist and man of letters, and one of the earliest oneirologists ....
.
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 drowsySomnolence
Somnolence is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods . It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm...
, a tendency dubbed the Tetris effect
Tetris effect
The Tetris effect occurs when people devote sufficient time and attention to an activity that it begins to overshadow their thoughts, mental images, and dreams...
. This effect has even been observed in amnesia
Amnesia
Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...
cs who otherwise have no memory
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
of the original activity. When the activity involves moving objects, as in the video game Tetris
Tetris
Tetris is a puzzle video game originally designed and programmed by Alexey Pajitnov in the Soviet Union. It was released on June 6, 1984, while he was working for the Dorodnicyn Computing Centre of the Academy of Science of the USSR in Moscow, Russian Soviet Federative Socialist Republic...
, 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 also. For example, Robert Stickgold
Robert Stickgold
Robert Stickgold is an Associate Professor of Psychiatry at Harvard Medical School and Beth Israel Deaconess Medical Center. A preeminent sleep researcher, Dr. Stickgold has dedicated his life to understanding the relationship between sleep and learning. He is also a very active educator...
recounts having experienced the touch of rocks while falling asleep after mountain climbing. This can also occur to people who have traveled 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, also 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. Many chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
players report the phenomenon of seeing the chess board and pieces during this state. New employees working stressful and demanding jobs often report doing work-related tasks in this period before sleep. This is very common amongst new waiters or waitresses in busy restaurants where they report having "Server Dreams" and restlessly wait tables in this state of mind, sometimes jolting them fully awake or preventing them from transitioning into actual sleep.
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 syndromeExploding head syndrome
Exploding head syndrome is a parasomnia condition that causes the sufferer occasionally to experience a tremendously loud noise as originating from within his or her own head, usually described as the sound of an explosion, roar, gunshot, loud voices or screams, a ringing noise, or the sound of...
). People may imagine their own name called or a doorbell ringing. Snatches of imagined speech
Spoken language
Spoken language is a form of human communication in which words derived from a large vocabulary together with a diverse variety of names are uttered through or with the mouth. All words are made up from a limited set of vowels and consonants. The spoken words they make are stringed into...
are common. While typically nonsensical and fragmented, these speech events can occasionally strike the individual as apt comments on—or summations of—their thought
Thought
"Thought" generally refers to any mental or intellectual activity involving an individual's subjective consciousness. It can refer either to the act of thinking or the resulting ideas or arrangements of ideas. Similar concepts include cognition, sentience, consciousness, and imagination...
s at the time. They often contain word play
Word play
Word play or wordplay is a literary technique in which the words that are used become the main subject of the work, primarily for the purpose of intended effect or amusement...
, neologisms and made-up name
Name
A name is a word or term used for identification. Names can identify a class or category of things, or a single thing, either uniquely, or within a given context. A personal name identifies a specific unique and identifiable individual person, and may or may not include a middle name...
s. Hypnagogic speech may manifest as the subject's own "inner voice
Internal monologue
Internal monologue, also known as inner voice, internal speech, or verbal stream of consciousness is thinking in words. It also refers to the semi-constant internal monologue one has with oneself at a conscious or semi-conscious level....
", or as the voices of others: familiar people or strangers. More rarely, poetry
Poetry
Poetry is a form of literary art in which language is used for its aesthetic and evocative qualities in addition to, or in lieu of, its apparent meaning...
or music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...
is heard.
Sleep paralysis
Humming, roaring, hissing, rushing, zapping, and buzzing noises are frequent in conjunction with sleep paralysisSleep paralysis
Sleep paralysis is paralysis associated with sleep that may occur in healthy persons or may be associated with narcolepsy, cataplexy, and hypnagogic hallucinations. The pathophysiology of this condition is closely related to the normal hypotonia that occurs during REM sleep. When considered to be a...
(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. Sleep paralysis is reportedly very frequent among narcoleptics. It occurs frequently in about 6% of the rest of the population, and occurs occasionally in 60%. In surveys from Canada, China, England, Japan and Nigeria, 20 to 60% of individuals reported having experienced SP at least once in their lifetime. The paralysis itself is frequently accompanied by additional phenomena. Typical examples include a feeling of being crushed or suffocated
Asphyxia
Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs...
, electric "tingles" or "vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
s", imagined speech and other noises, the imagined presence of a visible or invisible entity, and sometimes intense emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...
: fear
Fear
Fear is a distressing negative sensation induced by a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger...
or euphoria
Euphoria
Euphoria is an emotional and mental state defined as a sense of great elation and well being.Euphoria may also refer to:* Euphoria , a genus of scarab beetles* Euphoria, a genus name previously used for the longan and other trees...
and orgasm
Orgasm
Orgasm is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure...
ic feelings. SP has been proposed as an explanation for at least some alien abduction experiences and shadow people
Shadow people
Shadow people are supernatural shadow-like humanoid figures that, according to believers, are seen mostly in peripheral vision and move quickly...
hauntings.
Other sensations
Gustatory, olfactory and thermalThermoception
Thermoception or thermoreception is the sense by which an organism perceives temperature. The details of how temperature receptors work are still being investigated. Ciliopathy is associated with decreased ability to sense heat, thus cilia may aid in the process...
sensations in hypnagogia have all been reported, as well as tactile sensations (including those kinds classed as paresthesia
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
or formication
Formication
Formication is the medical term for a sensation that resembles that of insects crawling on the skin. It is one specific form of a set of sensations known as paresthesia, which also include the more common prickling, tingling sensation of "pins and needles"...
). Sometimes there is synesthesia
Synesthesia
Synesthesia , from the ancient Greek , "together," and , "sensation," is a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway...
; many people report seeing a flash of light or some other visual image in response to a real sound. Proprioceptive effects may be noticed, with numbness and changes in perceived body size and proportions, feelings of floating or bobbing, and out-of-body experience
Out-of-body experience
An out-of-body experience is an experience that typically involves a sensation of floating outside of one's body and, in some cases, perceiving one's physical body from a place outside one's body ....
s. Perhaps the most common experience of this kind is the falling sensation, and associated hypnic jerk
Hypnic jerk
A hypnic jerk, hypnagogic jerk, sleep start, or night start, is an involuntary myoclonic twitch which occurs during hypnagogia, just as a person is beginning to fall asleep, often causing them to awaken suddenly. Physically, hypnic jerks resemble the "jump" experienced by a person when...
, encountered by many people, at least occasionally, while drifting off to sleep.
Cognitive and affective phenomena
ThoughtThought
"Thought" generally refers to any mental or intellectual activity involving an individual's subjective consciousness. It can refer either to the act of thinking or the resulting ideas or arrangements of ideas. Similar concepts include cognition, sentience, consciousness, and imagination...
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
Empathy
Empathy is the capacity to recognize and, to some extent, share feelings that are being experienced by another sapient or semi-sapient being. Someone may need to have a certain amount of empathy before they are able to feel compassion. The English word was coined in 1909 by E.B...
) and diffuse-absorbed attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
." Hypnagogic cognition
Cognition
In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
, in comparison with that of normal, alert wakefulness, is characterized by heightened suggestibility
Suggestibility
Suggestibility is the quality of being inclined to accept and act on the suggestions of others.A person experiencing intense emotions tends to be more receptive to ideas and therefore more suggestible. Generally, suggestibility decreases as age increases...
, illogic and a fluid association of idea
Idea
In the most narrow sense, an idea is just whatever is before the mind when one thinks. Very often, ideas are construed as representational images; i.e. images of some object. In other contexts, ideas are taken to be concepts, although abstract concepts do not necessarily appear as images...
s. Subjects are more receptive in the hypnagogic state to suggestion
Suggestion
Suggestion is the psychological process by which one person guides the thoughts, feelings, or behaviour of another. Nineteenth century writers on psychology such as William James used the words "suggest" and "suggestion" in senses close to those they have in common speech—one idea was said to...
from an experimenter than at other times, and readily incorporate external stimuli
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
into hypnagogic trains of thought and subsequent dreams. This receptivity has a physiological parallel; EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
readings show elevated responsiveness to sound around the onset of sleep.
Herbert Silberer
Herbert Silberer
Herbert Silberer was a Viennese psychoanalyst involved with the professional circle surrounding Sigmund Freud which included other pioneers of psychological study as Carl Jung, Alfred Adler and others...
described a process he called autosymbolism, whereby hypnagogic hallucinations seem to represent, without repression
Psychological repression
Psychological repression, also psychic repression or simply repression, is the psychological attempt by an individual to repel one's own desires and impulses towards pleasurable instincts by excluding the desire from one's consciousness and holding or subduing it in the unconscious...
or censorship, whatever one is thinking at the time, turning abstract idea
Idea
In the most narrow sense, an idea is just whatever is before the mind when one thinks. Very often, ideas are construed as representational images; i.e. images of some object. In other contexts, ideas are taken to be concepts, although abstract concepts do not necessarily appear as images...
s into a concrete image
Mental image
A mental image is an experience that, on most occasions, significantly resembles the experience of perceiving some object, event, or scene, but occurs when the relevant object, event, or scene is not actually present to the senses...
, which may be perceived as an apt and succinct representation thereof.
The hypnagogic state can provide insight
Insight
Insight is the understanding of a specific cause and effect in a specific context. Insight can be used with several related meanings:*a piece of information...
into a problem
Problem
A problem is an obstacle, impediment, difficulty or challenge, or any situation that invites resolution; the resolution of which is recognized as a solution or contribution toward a known purpose or goal...
, the best known example being August Kekulé’s realization that the structure of benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
was a closed ring after dozing in front of a fire and seeing molecules forming into snakes, one of which grabbed its tail in its mouth. Many other artist
Artist
An artist is a person engaged in one or more of any of a broad spectrum of activities related to creating art, practicing the arts and/or demonstrating an art. The common usage in both everyday speech and academic discourse is a practitioner in the visual arts only...
s, writer
Writer
A writer is a person who produces literature, such as novels, short stories, plays, screenplays, poetry, or other literary art. Skilled writers are able to use language to portray ideas and images....
s, scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s and inventors—including Beethoven
Ludwig van Beethoven
Ludwig van Beethoven was a German composer and pianist. A crucial figure in the transition between the Classical and Romantic eras in Western art music, he remains one of the most famous and influential composers of all time.Born in Bonn, then the capital of the Electorate of Cologne and part of...
, Richard Wagner
Richard Wagner
Wilhelm Richard Wagner was a German composer, conductor, theatre director, philosopher, music theorist, poet, essayist and writer primarily known for his operas...
, Walter Scott
Walter Scott
Sir Walter Scott, 1st Baronet was a Scottish historical novelist, playwright, and poet, popular throughout much of the world during his time....
, Salvador Dalí
Salvador Dalí
Salvador Domènec Felip Jacint Dalí i Domènech, Marquis de Púbol , commonly known as Salvador Dalí , was a prominent Spanish Catalan surrealist painter born in Figueres,Spain....
, Thomas Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...
and Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
—have credited hypnagogia and related states with enhancing their creativity
Creativity
Creativity refers to the phenomenon whereby a person creates something new that has some kind of value. What counts as "new" may be in reference to the individual creator, or to the society or domain within which the novelty occurs...
. A 2001 study by Harvard psychologist Deirdre Barrett
Deirdre Barrett
Deirdre Barrett, Ph.D. is an author and psychologist who teaches at Harvard Medical School. She is known for her research on dreams, hypnosis, and imagery and has written on evolutionary psychology. Barrett is a Past President of The International Association for the Study of Dreams and of the...
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.
A feature that hypnagogia shares with other stages of sleep is amnesia
Amnesia
Amnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...
. But this is a selective forgetfulness, affecting the hippocampal memory system, which is responsible for episodic
Episodic memory
Episodic memory is the memory of autobiographical events that can be explicitly stated. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory...
or autobiographical memory
Autobiographical memory
Autobiographical memory is a memory system consisting of episodes recollected from an individual's life, based on a combination of episodic and semantic memory.-Formation:Conway and Pleydell-Pearce proposed that autobiographical...
, rather than the neocortical memory system, responsible for semantic memory
Semantic memory
Semantic memory refers to the memory of meanings, understandings, and other concept-based knowledge unrelated to specific experiences. The conscious recollection of factual information and general knowledge about the world is generally thought to be independent of context and personal relevance...
. It has been suggested that hypnagogia and REM sleep help in the consolidation of semantic memory, but the evidence for this has been disputed. For example, suppression of REM sleep due to antidepressant
Antidepressant
An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...
s and lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s to the brainstem has not been found to produce detrimental effects on cognition.
Hypnagogic phenomena may be interpreted as visions
Hallucination
A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
, prophecies, premonitions, apparitions
Apparitional experience
In psychology and parapsychology, an apparitional experience is an anomalous, quasi-perceptual experience.It is characterized by the apparent perception of either a living being or an inanimate object without there being any material stimulus for such a perception...
and inspiration (artistic
Artistic inspiration
Inspiration refers to an unconscious burst of creativity in a literary, musical, or other artistic endeavour. Literally, the word means "breathed upon," and it has its origins in both Hellenism and Hebraism. The Greeks believed that inspiration came from the muses, as well as the gods Apollo and...
or divine
Divine Inspiration
Divine Inspiration is a British music group that formed in 2002. The group consists of singer Sarah-Jane Scott, DJ Paul Crawley, David Lewin and Lee Robinson. They have had two singles that charted in the United Kingdom. Their first release, "The Way " peaked at number five in the UK Singles Chart...
), 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 NREM sleep, but may also occur with pre-sleep alpha waveAlpha wave
Alpha waves are neural oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells in humans...
s. Davis et al. found short flashes of dreamlike imagery at the onset of sleep to correlate with drop-offs in alpha EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
activity. Hori et al. regard sleep onset hypnagogia as a state distinct from both wakefulness and sleep with unique electrophysiological, behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...
al and subjective
Subjectivity
Subjectivity refers to the subject and his or her perspective, feelings, beliefs, and desires. In philosophy, the term is usually contrasted with objectivity.-Qualia:...
characteristics, while Germaine et al. have demonstrated a resemblance between the EEG power spectra
Spectral density
In statistical signal processing and physics, the spectral density, power spectral density , or energy spectral density , is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has dimensions of power per hertz...
of spontaneously occurring hypnagogic images, on the one hand, and those of both REM sleep and relaxed wakefulness, on the other.
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
Alpha wave
Alpha waves are neural oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells in humans...
(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
Sleep spindle
A sleep spindle is a burst of brain activity visible on an EEG that occurs during stage 2 sleep. It consists of 12–14 Hz waves that occur for at least 0.5 seconds.-Function:...
(stages 8–9). Germaine and Nielsen found spontaneous hypnagogic imagery to occur mainly during Hori sleep onset stages 4 (EEG flattening) and 5 (theta ripples).
The "covert-rapid-eye-movement" hypothesis proposes that hidden elements of REM sleep emerge during the wakefulness-sleep transition stage. 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.
Respiratory pattern changes have also been noted in the hypnagogic state, in addition to a lowered rate of frontalis muscle
Frontalis muscle
The Frontalis muscle , also known as the occipitofrontalis or epicranius, is thin, of a quadrilateral form, and intimately adherent to the superficial fascia. It is broader than the Occipitalis and its fibers are longer and paler in color...
activity.
Daydreaming and waking reveries
MicrosleepMicrosleep
A microsleep is an episode of sleep which may last for a fraction of a second or up to thirty seconds. Often, it is the result of sleep deprivation, mental fatigue, depression, sleep apnea, hypoxia, narcolepsy, or hypersomnia...
(short episodes of immediate sleep onset) may intrude into wakefulness at any time in the wakefulness-sleep cycle, due to sleep deprivation
Sleep deprivation
Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the...
and other conditions, resulting in impaired cognition, amnesia.
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. DPH is typically encountered when one is "tired, bored, suffering from attention fatigue
Directed attention fatigue
Directed Attention Fatigue is a neurological phenomenon that results from overuse of the brain’s inhibitory attention mechanisms, which handle incoming distractions while maintaining focus on a specific task. The greatest threat to a given focus of attention is competition from other stimuli that...
, 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. Gustelle and Oliveira define DPH as "dissociative, trance
Trance
Trance denotes a variety of processes, ecstasy, techniques, modalities and states of mind, awareness and consciousness. Trance states may occur involuntarily and unbidden.The term trance may be associated with meditation, magic, flow, and prayer...
-like, [...] but, unlike a daydream
Daydream
A daydream is a visionary fantasy, especially one of happy, pleasant thoughts, hopes or ambitions, imagined as coming to pass, and experienced while awake. There are many types of daydreams, and there is no consistent definition amongst psychologists. The general public also uses the term for a...
, [...] not self-directed"—however, daydreams and waking reveries are often characterised as "passive", "effortless", and "spontaneous", while hypnagogia itself can sometimes be influenced by a form of autosuggestion
Autosuggestion
Autosuggestion is a psychological technique that was developed by apothecary Émile Coué from the late 19th century to the early 20th century.-Origins:...
, or "passive concentration", so these sorts of episode may in fact constitute a continuum between directed fantasy and the more spontaneous varieties of hypnagogia. Others have emphasized the connections between fantasy, daydreaming, dreams and hypnosis.
In his book, Zen and the Brain
Zen and the Brain
Zen and the Brain: Toward an Understanding of Meditation and Consciousness is a book authored by James H. Austin. First published in 1998, the book's aim is to establish links between the neurological workings of the human brain and meditation....
, James H. Austin
James H. Austin
James H. Austin is Clinical Professor of Neurology, University of Missouri Health Science Center, and Emeritus Professor of Neurology, University of Colorado Health Science Center. Austin is the author of his well known book Zen and the Brain, which aims to establish links between the neurological...
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.
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.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, sleep manipulation, the use of techniques to "hover on the edge of sleep" thereby extending the duration of the hypnagogic state, and training in the art of introspection to heighten the subject's powers of observation and attention.
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), to the use of biofeedback devices to induce a "theta" state, characterized by relaxation and theta EEG activity. The theta state is produced naturally the most when we are dreaming. It has also been linked to paranormal activities, and Rick Straussman has argued that it triggers the release of DMT from the pineal gland, causing a dreaming state.
Another method is to induce a state said to be subjectively similar to sleep onset in a Ganzfeld
Ganzfeld effect
The Ganzfeld effect is a phenomenon of visual perception caused by staring at an undifferentiated and uniform field of color. The effect is described as the loss of vision as the brain cuts off the unchanging signal from the eyes...
setting, a form of sensory deprivation
Sensory deprivation
Sensory deprivation or perceptual isolation is the deliberate reduction or removal of stimuli from one or more of the senses. Simple devices such as blindfolds or hoods and earmuffs can cut off sight and hearing respectively, while more complex devices can also cut off the sense of smell, touch,...
. But the assumption of identity between the two states may be unfounded. The average EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
spectrum in Ganzfeld is more similar to that of the relaxed waking state than to that of sleep onset. 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."
Hypnagogia in film
- Dracula
- GhostbustersGhostbustersGhostbusters is a 1984 American science fiction comedy film directed by Ivan Reitman and written by Dan Aykroyd and Harold Ramis. The film stars Bill Murray, Dan Aykroyd, Sigourney Weaver, Harold Ramis, and Rick Moranis and follows three eccentric parapsychologists in New York City, who start a...
- MarianneMarianne (2011 film)Marianne is a 2011 Swedish horror film, directed by Filip Tegstedt, that premiered at the 2011 Fantasia International Film Festival on 2 August 2011....
- Paranormal Activity
See also
- Sleep onsetSleep onsetSleep onset is the transition from wakefulness into sleep. Sleep onset usually transmits into non-rapid eye movement sleep but in certain situations like narcolepsy, it is possible to transmit from wakefulness directly into rapid eye movement sleep...
- False awakeningFalse awakeningA false awakening is a vivid and convincing dream about awakening from sleep, while the dreamer in reality continues to sleep. After a false awakening, subjects often dream they are performing daily morning rituals such as cooking, cleaning and eating...
- Hag in folklore
- Hypnic jerkHypnic jerkA hypnic jerk, hypnagogic jerk, sleep start, or night start, is an involuntary myoclonic twitch which occurs during hypnagogia, just as a person is beginning to fall asleep, often causing them to awaken suddenly. Physically, hypnic jerks resemble the "jump" experienced by a person when...
- Lucid dream
- MeditationMeditationMeditation is any form of a family of practices in which practitioners train their minds or self-induce a mode of consciousness to realize some benefit....
- NightmareNightmareA nightmare is an unpleasant dream that can cause a strong negative emotional response from the mind, typically fear or horror, but also despair, anxiety and great sadness. The dream may contain situations of danger, discomfort, psychological or physical terror...
- Segmented sleepSegmented sleepSegmented sleep, also known as divided sleep, bimodal sleep pattern, or interrupted sleep, is a polyphasic or biphasic sleep pattern where two or more periods of sleep are punctuated by a period of wakefulness....
- Sleep disorderSleep disorderA sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning...
- Sleep paralysisSleep paralysisSleep paralysis is paralysis associated with sleep that may occur in healthy persons or may be associated with narcolepsy, cataplexy, and hypnagogic hallucinations. The pathophysiology of this condition is closely related to the normal hypotonia that occurs during REM sleep. When considered to be a...
- Yoga NidraYoga NidraYoga-nidra or "yogi sleep" is a sleep-like state which yogis report to experience during their meditations.The practice of yoga relaxation has been found to reduce tension and anxiety. The autonomic symptoms of high anxiety such as headache, giddiness, chest pain, palpitations, sweating, abdominal...
- Dream yogaDream yogaDream Yoga or Milam — the Yoga of the Dream State are a suite of advanced tantric sadhana of the entwined Mantrayana lineages of Dzogchen...
- ConsciousnessConsciousnessConsciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
- Form constantForm constantA form constant is one of several geometric patterns which are recurringly observed during hallucinations and altered states of consciousness.-History:...
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.
External links
- "Hypnagogic and hypnopompic hallucinations: pathological phenomena?" article in the British Journal of PsychiatryBritish Journal of PsychiatryThe British Journal of Psychiatry is a peer-reviewed medical journal published monthly by the Royal College of Psychiatrists containing original research, systematic reviews, commentaries on contentious articles, short reports, a comprehensive book review section, and a correspondence column...
- Gary Lachman on Hypnagogia