Hypnagogia, False Awakenings & Sleep Paralysis

This article explains the phenomenon of hypnagogia. It is also relevant for the themes of false awakening and sleep paralysis, which are also covered in this article and linked back to the phenomena of hypnagogia. At the end of this article you will see some exercises which utilise hypnagogia for lucid dreaming (WILD - Wake-Initiated Lucid Dreaming) and also for inducing an OBE and using the OBE-Exit technique for transforming the experience into a full lucid dream.

Hypnagogia

Hynpnagogia is a transitional state of consciousness between wakefulness and sleep, which happens at the onset of sleep – so while the individual is drifting off to sleep. It is contrasted with hypnopompia, which happens at the onset of wakefulness. However, generally, hypnagogia is used to cover the transitional state between wake and sleep which happens both while we are falling asleep or waking up, and therefore, hypnagogia broadly refers to both types. Sleep onset is the transition from wakefulness into sleep. Sleep onset usually transmits into non-rapid eye movement sleep (NREM sleep) but under certain circumstances (i.e. narcolepsy or by using lucid dream induction techniques, such as WILD – Wake-Initiated Lucid Dreaming) it is possible to transit from wakefulness directly into rapid eye movement sleep (REM sleep, where dreaming takes place).

Other terms used to describe the hypnagogic state include ‘presomnal’ or ‘anthypnic sensations’, ‘visions of half-sleep’, ‘oneirogogic images’ and ‘phantasmata’,’the borderland of sleep’, ‘praedormitium’, ‘borderland state’, ‘half-dream state’, ‘pre-dream condition’, ‘sleep onset dreams’, ‘dreamlets’ and ‘wakefulness-sleep transition’ (WST). Mental phenomena which can occur during this period of ‘threshold consciousness’ phase include lucid thought, lucid dreaming, hallucinations, and sleep paralysis.

This form of 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 – therefore they are in a ‘wake-sleep limbo’. Such transitions are usually brief, but can be extended by sleep disturbance or deliberate induction, for example during meditation or lucid dream induction using the WILD (Wake-Initiated Lucid Dream) technique. You experience some elements of sleep mixed with some aspects of wakefulness, explains neurologist, Dr Milena Pavlova. 

In some ways, hypnagogia is a perfect state for introspection and expansive thought processes - you get the free flow of ideas and associations that occurs during REM sleep and dreaming, when the brain reviews and processes memories, thoughts and feelings - but you’re still sufficiently awake to be somewhat conscious of what is happening. For this reason, some artists have found hypnagogia to be a rich source of ideas and inspiration.

Early references to the phenomenon of hypnagogia are found in the writings of Aristotle, Iamblichus, Cardano, Simon Forman and Swedenborg. Romanticism brought a renewed interest in the subjective experience of the edges of sleep and other states of altered consciousness. 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’. Charles Dickens' Oliver Twist (1837), contains elaborate descriptions of the hypnagogic state in 2 different scenes.

Serious scientific inquiry into the phenomenon of hypnagogia began in the 19th century with Johannes Peter Müller, Jules Baillarger and Alfred Maury, and continued into the 20th century with Leroy. The advent of electroencephalography (EEG) has supplemented the introspective methods of early researchers with physiological data which shows the brainwave activity which occurs in the hypnagogic state. 

The search for neural correlates for hypnagogic imagery began with Davis in the 1930s and continues with increasing sophistication and new neuroscientific advancements. While the dominance of the behaviourist paradigm led to a decline in research the later 20th century has seen a revival, with investigations of hypnagogia and related altered states of consciousness 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’. The word hypnagogia entered the popular psychology literature through Dr Andreas Mavromatis (1983). Important reviews of the scientific literature have been made by Leaning, Schacter, Richardson & Mavromatis.

Scientific explanations

Physiological studies have tended to concentrate on hypnagogia in the context of spontaneous sleep onset experiences. Such experiences are associated especially with stage 1 of NREM sleep, but may also occur with pre-sleep alpha waves. Davis et al (1937) found short flashes of dreamlike imagery at the onset of sleep to correlate with drop-offs in alpha EEG activity. Hori et al (1993) regard sleep onset hypnagogia as a state distinct from both wakefulness and sleep with unique electrophysiological, behavioural and subjective characteristics, while Germaine et al (1995) 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 the nature of the EEG state which accompanies imagery in the transition from wakefulness to sleep in a more precise manner, Hori et al proposed a scheme of 9 EEG stages defined by varying proportions of brainwave frequency. Germaine and Nielsen found spontaneous hypnagogic imagery to occur mainly during Hori sleep onset stages 4 (EEG flattening) and 5 (theta ripples). This is why theta brainwaves have been associated with lucid dreaming.

Scientists have observed the presence of both alpha brain waves - which are the dominant brainwave frequency when we are conscious but relaxed, for instance when daydreaming or meditating, and theta brainwaves - which are associated with restorative sleep, during hypnagogia. 

Typically, these brainwaves tend to occur only separately, and it may be the unique combination that gives rise to unusual visions and sensations during the hypnagogic state. The state is also marked by reduced activity in the prefrontal cortex of the brain, which is involved in planning, decision-making, logic and social behaviour. 

The ‘covert-rapid-eye-movement’ hypothesis proposes that hidden elements of REM sleep emerge during the wakefulness-sleep transition stage. Support for this theory comes from Bódicz et al who note a significant similarity between WST (wakefulness-sleep transition) EEG and REM sleep EEG. Respiratory pattern changes have also been noted in the hypnagogic state, in addition to a lowered rate of frontalis muscle activity.

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 advantages and disadvantages. Amnesia, coupled with the typically fleeting nature of hypnagogic experiences contribute to the difficulty of studying hypnagogia. 

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 (i.e. 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 and some evidence suggests it might be possible to encourage theta brainwave activity by using electrodes in a laboratory or binaural beats to synchronise brainwave activity. 

The theta state has also been linked to paranormal activities. Rick Strassman has argued that it triggers the release of DMT from the pineal gland, causing a dreaming state. Another method is to induce an altered state (which is said to be subjectively similar to sleep onset), by using a Ganzfeld setting - a form of sensory deprivation. But the assumption of identity between the 2 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 (2000) 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’.

Sensory experiences & hallucinations

Transition to and from sleep may be attended by a wide variety of sensory experiences. These can occur individually or combined and can range from the vague and barely perceptible to vivid hallucinations with physical sensations. 

The most commonly reported – and most researched – aspect of hypnagogia are the sensory features known as phospenes, which may manifest as either random speckles, lines or geometric shapes and patterns. These may form constants or figurative (representational) images. The phosphenes may be monochromatic (black and white) or brightly coloured; may move around or be completely still. Some phosphenes may appear flat, while others may appear as 3-dimensional and give the impression of perspective and depth. 

It is often common to see imagery which gives the impression of movement through a tunnel of light. Images tend to change rapidly, and unlike the imagery and content of our proper dreams, tends to be static and have no narrative meaning. 

Some people report that their hypnagogia is a state which gradually transitions into fragmentary dreams. Those who attempt to use the WILD technique for lucid dreaming report may find it helpful to use the hypnagogic imagery in the dream visualisation stage in inducing the lucid dream. 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 is an experience which often happens to people who have spent a long time doing a repetitive activity before sleep. This repetitive activity then dominates their imagery as they drift off to sleep. This effect has been observed in amnesiacs who have no memory of the original activity which triggered it. When the original activity involves moving objects, the corresponding hypnagogic imagery is also perceived as moving. 

This perception of something we have experienced in our waking life is not restricted to these visual images - Robert Stickgold recounts having experienced the touch of rocks while falling asleep after mountain climbing. 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 – they report that they can feel the waves as they drift to sleep. 

Similarly, people who have spent the day skiing who continue to ‘feel snow’ under their feet and people who have spent considerable time jumping on a trampoline report that they can feel the up-and-down motion before they go to sleep. Many chess players claim that they experience 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. The reason for this is that you will have formed new neuronal connections in your brain by repeating those repetitive tasks. This then causes them to fire and strengthen as you fall asleep, and from an evolutionary perspective, this is what helps us to further cement abilities that we have learned during the day in order to improve our performance.

Hypnagogic hallucinations are often auditory or have an auditory component. Like the visuals, hypnagogic sounds vary in intensity from faint impressions to very loud noises, such as crashes and bangs (‘exploding head syndrome’). People may imagine their own name called out, crumpling bags, white noise, or a doorbell ringing - snatches of imagined speech are also common. While typically nonsensical and fragmented, these speech events can occasionally strike the individual as apt comments on - or summations of - their thoughts at the time. They often contain word play, neologisms and made-up names. 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.

Noises such as humming, roaring, hissing, rushing, zapping and buzzing noises are frequently experienced in conjunction with sleep paralysis. This happens when the REM atonia (muscle weakness) 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 - 60% of individuals reported having experienced sleep paralysis 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 ‘vibrations’, imagined speech and other noises, the imagined presence of a visible or invisible entity, and sometimes intense emotion: fear or euphoria and orgasmic feelings. Sleep paralysis has been proposed as an explanation for at least some alien abduction experiences, the Night Hag and shadow people hauntings. These experiences are often referred to as ‘night terrors’.

Gustatory, olfactory and thermal sensations in hypnagogia have all been reported, as well as tactile sensations (including those kinds classed as paresthesia 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. Proprioceptive effects may be noticed, with numbness and changes in perceived body size and proportions, feelings of floating or bobbing, and the perception of an out-of-body experience (OBE). 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.

Hypnic jerks

A ‘hypnic jerk’ – also called a ‘hypnagogic jerk’, ‘sleep start’, ‘sleep twitch’, ‘night start’, or ‘jump’, is a sudden involuntary twitch which occurs just as a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the ‘jump’ experienced by a person when startled, and is sometimes accompanied by a falling sensation. 

Hypnic jerks are associated with a rapid heartbeat, quickened breathing, swearing and sometimes a sensory experience of 'shock’ or 'falling into the void’. A higher occurrence is reported in people with irregular sleep schedules or disturbed sleep patterns. According to the American Academy of Sleep Medicine there is a wide range of potential causes, including anxiety, high intake of caffeine, stress and performing strenuous activities in the evening. 

However, most hypnic jerks occur essentially at random in healthy people. According to a study on sleep disturbances in the Journal of Neural Transmission (2003), a hypnic jerk occurs during the non-rapid eye movement (NREM) sleep cycle and is an ‘abrupt muscle action flexing movement, generalized or partial and asymmetric, which may cause arousal, with an illusion of falling’. Hypnic jerks are more frequent in childhood with 4 - 7 per hour at the age ranging from 8 - 12 years old. This decreases toward 1 - 2 per hour at 65 - 80 years old. According to Marianne Middleton, clinical coordinator at the Lawrence Memorial Hospital Sleep Disorders Centre, hypnic jerks can lead to a vicious circle, because if an individual loses sleep because they are constantly jerking awake, they are likely to become fatigued and perhaps develop anxiety or worry about falling sleep – the more anxious and exhausted you are, the more likely you are to suffer from a hypnic jerk.

Thought processes on the edge of sleep also tend to differ radically from those of ordinary wakefulness. During the hypnagogic state, the mind is ‘fluid and hyperassociative’, giving rise to images that can ‘express layers of memories and sensations’ states dream researcher, Michelle Carr. 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 ideas. 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 ideas 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 while half-asleep in front of a fire and seeing molecules forming into snakes, one of which grabbed its tail in its mouth. 

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. Author Mary Shelley claimed that she got the inspiration for Frankenstein from a ‘waking dream’ in the early hours of the morning, stating: ‘I saw with eyes shut, but acute mental vision’. 

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. Sirley Marques Bonham, a consciousness researcher at the University of Texas at Austin, states: ‘Hypnagogia is the shortest path for communication from our subconscious…Your subconscious mind might send you solutions through imagery or other sensations’.

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 antidepressants and lesions to the brainstem has not been found to produce detrimental effects on cognition.

Gurstelle & 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 waking dream may be forgotten even though the individual remembers having had such an experience. 

Gustelle & Oliveira define DPH as ‘dissociative, trance-like, [...] but, unlike a daydream, [...] not self-directed’ - however, daydreams and waking reveries are often characterised as ‘passive’, ‘unconscious’ 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: Toward an Understanding of Meditation & Consciousness (1999), 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.

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.

False awakenings

A false awakening is often associated with the concepts of hypnagogia and sleep paralysis, as both phenomena may occur at the same time as the false awakening. A false awakening is a vivid and convincing dream about awakening from sleep, when in reality, the dreamer continues to sleep. After a false awakening, subjects often dream they are performing daily morning rituals such as cooking, cleaning and eating. 

A subset of false awakenings, namely those in which one dreams that one has awoken from sleep that featured dreams, take on aspects of a double dream or a dream within a dream. A classic example is the double false awakening of the protagonist in Gogol's Portrait (1835).

A false awakening may occur following a normal non-lucid dream or a lucid dream (one in which the dreamer has been consciously aware that they were dreaming while in the dream state). Particularly, if the false awakening follows a lucid dream, the false awakening may turn into a ‘pre-lucid dream’ – i.e. one in which the dreamer may start to wonder if they are really awake and may or may not come to the correct conclusion. This is the precise time a reality check would be useful to allow the dreamer to ascertain if they are still dreaming. 

In a study by Harvard psychologist Deirdre Barrett, 2,000 dreams from 200 subjects were examined and it was found that false awakenings and lucidity were significantly more likely to occur within the same dream or within different dreams of the same night. False awakenings often preceded lucidity as a cue, but they could also follow the realization of lucidity, often losing it in the process. If the false awakening precedes lucidity – i.e. the dreamer realises they are still asleep and dreaming, it is possible to transform the experience into a full lucid dream for those experienced in maintaining this precarious state. 

Another type of false awakening is a 'continuum', where the individual falls asleep in real life, but in their subsequent dream, the brain simulates the dreamer as though they were still awake; i.e. the dreamer thinks he or she is still awake, but in reality, is asleep. At times the individual can perform actions unknowingly. The movie A Nightmare on Elm Street (1984) popularized this phenomenon and can be related to that of sleep-walking or carrying out actions in a state of unconsciousness.

Certain aspects of life may be dramatized, bizarre or out of place in false awakenings. When the dreamer ‘falsely awakes’ and finds themselves in their bedroom, things may seem wrong – details about the appearance of the room, not being able to talk or difficulty reading (purportedly reading in lucid dreams is often difficult or impossible) or things/people behaving in odd ways. In some experiences, the subject's senses are heightened or changed completely. 

When noticing such phenomena, it is vital that you perform a reality check which will – hopefully – confirm that you are still asleep and dreaming, and will trigger lucidity. Because the mind still dreams after a false awakening, there may be more than one false awakening in a single dream. Individuals may dream they wake up and start to perform their usual morning rituals, only to suddenly awake again in bed (still in a dream), begin the process once more and then awaken again - and so forth. The philosopher Bertrand Russell claimed to have experienced ‘about 100’ false awakenings in succession while coming around from a general anaesthetic.

In Celia Green, Lucid Dreams (1968), the author describes 2 main types of false awakening:

• Type 1 - Type 1 is the more common - in which the dreamer seems to wake up, but not necessarily in realistic surroundings (i.e. not in their own bedroom) and a pre-lucid dream may continue. More commonly, dreamers will believe they have awakened, and then either wake up for real in their own bed or ‘fall back asleep’ in the dream. A common false awakening is a ‘late for work’ scenario. A person may ‘wake up’ in a typical bedroom room, with most things looking normal, and ‘realize’ they overslept and are late for work or school - clocks, if found in the dream, will show time indicating that fact. The resulting panic is often strong enough wake the person up for real (much like from a nightmare). Another common Type 1 example of false awakening can result in bedwetting - in this scenario the dreamer has false awakened and (while in the state of dream) has performed all the traditional behaviours that precede urinating -including arising from bed and going into the bathroom, while still asleep and in bed in reality. This is why lucid dreamers always advise that if you find yourself ‘waking up’ to use the bathroom in the middle of the night, to perform a reality check, just to be sure it isn’t your dreaming mind playing tricks on you.
• Type 2 - Type 2 false awakenings seem to be considerably less common. They are characterized as occurring when the individual appears to wake up in a realistic manner, but to an atmosphere of suspense. His surroundings may at first appear normal, and he may gradually become aware of something ‘uncanny’ or unnatural in the atmosphere and might perhaps experience odd visions, sounds and/or movements. Additionally he may ‘awaken’ immediately to a ‘stressed’ and ‘stormy’ atmosphere, characterized by feelings of suspense, excitement or apprehension.

Charles McCreery (1997) drew attention to the similarity between this description and the reports by the German psychopathologist Karl Jaspers (1923) of the so-called ‘primary delusionary experience’ (a general feeling that precedes more specific delusory belief). Jaspers claimed:

‘Patients feel uncanny and that there is something suspicious afoot. Everything gets a new meaning. The environment is somehow different - not to a gross degree - perception is unaltered in itself but there is some change which envelops everything with a subtle, pervasive and strangely uncertain light [...] Something seems in the air which the patient cannot account for, a distrustful, uncomfortable, uncanny tension invades him.

McCreery suggests this phenomenological similarity is not coincidental, and results from the idea that both phenomena - the Type 2 false awakening and the primary delusionary experience - are phenomena of sleep. He suggests that the primary delusionary experience, like other phenomena of psychosis (such as hallucinations and secondary or specific delusions), represents an intrusion of processes associated with stage 1 sleep into the waking consciousness. 

It is suggested that the reason for these intrusions is that the psychotic subject is in a state of hyper-arousal - a state that can lead to what Ian Oswald (1962) called ‘micro-sleeps’ in waking life. ‘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, resulting in impaired cognition and even amnesia. Individuals may also experience sleep paralysis during a false awakening.

Sleep paralysis

Sleep paralysis is the phenomenon in which a person either during falling asleep (hypnagogia) or awakening (hypnopompia), temporarily experiences an inability to move, speak or physically react.

It occurs in the transitional state between wakefulness and sleep, characterized by muscle atonia (muscle weakness) and often accompanied by terrifying and unusually powerful hallucinations (such as an intruder in the room) to which one is unable to react due to paralysis, and physical experiences (such as strong current running through the upper body). These sensations, perceptions or hallucinations are those we have discussed above in relation to hypnagogia.

Isolated sleep paralysis is commonly seen in individuals who have been diagnosed with narcolepsy. Approximately 30 - 50% of people that have been diagnosed with narcolepsy have experienced sleep paralysis as an auxiliary symptom. The prevalence of sleep paralysis in the general population is approximately 6.2%. A majority of the individuals who have experienced sleep paralysis have sporadic episodes that occur once a month to once a year (isolated sleep paralysis). Only 3% of individuals experiencing sleep paralysis (which is not associated with a neuromuscular disorder) have nightly episodes (recurrent isolated sleep paralysis). 

Sleep paralysis is just as common for males as it is for females; however, different age groups have been found to be more susceptible to developing isolated sleep paralysis - approximately 36% of the general population that experiences isolated sleep paralysis is likely to develop it between 25 and 44 years of age.

The original definition of sleep paralysis was codified by Samuel Johnson as a ‘nightmare’ in A Dictionary of the English Language - a term that evolved into our modern definition. Sleep paralysis was widely considered the work of demons - more specifically incubi - which were thought to sit on the chests of sleepers. In Old English, the name for these beings was mare or mære (from a proto-Germanic *marōn, cf Old Norse mara), hence comes the mare in the word nightmare. The word might be etymologically cognate to Greek Marōn (in the Odyssey) and Sanskrit Māra.

Various forms of magic and spiritual possession were also advanced as causes. In 19th century Europe, the diet and digestion system were thought to be responsible. For example, in Charles Dickens's A Christmas Carol (1843), Ebenezer Scrooge attributes the ghost he sees to ‘... an undigested bit of beef, a blot of mustard, a crumb of cheese, a fragment of an underdone potato...’ In a similar vein, the Household Cyclopedia (1881) offered advice about diet and digestion in order to avoid nightmares.

One hypothesis is that sleep paralysis results from disrupted REM sleep. During normal REM sleep, the individual has muscle atonia (muscle weakness) which prevents sleepers from acting out their dreams and putting themselves or others into potentially dangerous physical situations. Sleep paralysis has been linked to disorders such as narcolepsy, migraines, anxiety disorders and obstructive sleep apnea - however, it can also occur in isolation. It has been found to occur in individuals who are attempting to induce lucid dreaming.

Sleep paralysis occurs either when falling asleep or when awakening from sleep. When it occurs upon falling asleep, the person remains aware while the body shuts down for REM sleep, a condition called hypnagogic or predormital sleep paralysis. When it occurs upon awakening, the person becomes aware before the REM cycle is complete, and it is called hypnopompic or postdormital. 

The paralysis can last from several seconds to several minutes, with some rare cases being hours and the individual may experience panic symptoms. As the correlation with REM sleep suggests, the paralysis is not complete - use of EOG traces shows that eye movement is still possible during such episodes; however, the individual experiencing sleep paralysis is often unable to speak.

Hypnagogic and hypnopompic visions, or hearing a demonic voice are symptoms commonly experienced during episodes of sleep paralysis. Some scientists have proposed this condition as an explanation for reports of hauntings by ghosts and alien visitations. There are 3 main types of visions that can be linked to pathologic neurophysiology – (1) the belief that there is an intruder in the room, (2) the incubus/succubus and (3) vestibular motor sensations.

(1) Intruder scenario

Many people who experience sleep paralysis are struck with a deep sense of terror when they sense a menacing presence in the room while paralyzed - hereafter referred to as ‘the intruder’. The intruder may take a variety of forms – from the familiar to something nightmarish and strange. A neurological interpretation of this phenomenon is that it results from a hyper-vigilant state created in the midbrain. More specifically, the emergency response is activated in the brain when individuals wake up paralyzed and feel vulnerable to attack. This helplessness can intensify the effects of the threat response well above the level typical of normal dreams, which could explain why such visions during sleep paralysis are so vivid and realistic. 

Normally the threat-activated vigilance system is a used as a protective mechanism which can differentiate between dangerous situations and to determine whether the fear response is appropriate. Some hypothesize that the threat vigilance system is evolutionarily biased to interpret ambiguous (unknown, unfamiliar) stimuli as dangerous, because ‘erring on the side of caution’ increases our survival chances. 

This hypothesis could account for why the threatening presence is often perceived as evil. The amygdala is heavily involved in the threat activation response mechanism, which is implicated in both intruder and incubus/succubus sleep paralysis visions. The specific pathway through which the threat-activated vigilance system acts is not well understood scientifically. 

One possibility is that the thalamus receives sensory information and sends it on the amygdala - which regulates emotional experience. Another is that the amygdaloid complex, anterior cingulate, and the structures in the pontine tegmentum, interact to create the vision we perceive during sleep paralysis. It is also highly possible that sleep paralysis hallucinations could result from a combination of these things. 

The anterior cingulate has an extensive array of cortical connections to other cortical areas - which enables it to integrate the various sensations and emotions into the unified sensorium (i.e. the unified sensory experience). The amygdaloid complex helps us interpret emotional experience and act appropriately and this is useful in directing the individual's attention to the most pertinent stimuli in a potentially dangerous situation so that the individual can take self-protective measures. Proper amygdaloid complex function requires input from the thalamus, which creates a thalamoamygdala pathway capable of bypassing the intense scrutiny of incoming stimuli. This enables quick responses in a potentially life-threatening situation. 

Typically, situations assessed as non-threatening are disregarded. In sleep paralysis, however, those pathways can become over-excited and move into a state of hyper-vigilance in which the mind perceives every single external stimulus as a threat. The hyper-vigilance response can lead to the creation of endogenous stimuli that contribute to the perceived threat. 

(2) Incubus/succubus scenario

A similar process may explain the experience of the incubus/succubus presence – an almost universal phenomenon which occurs with slight variations in people from all cultures - in which the evil presence is perceived by the subject to be attempting to suffocate them, either by pressing heavily on the chest or by strangulation. Some people report that the being tries to probe them or penetrate them in some way. 

Typically, this experience is known as 'Old Hag Syndrome' because the incubus/succubus-type being which appears often resembles an old hag. The ‘night hag’ is a generic name for a fantastical creature from the folklore of various peoples and cultures which is used to explain the phenomenon of sleep paralysis. A common description is that a person feels a presence of a supernatural malevolent being which immobilizes the person as if sitting on his/her chest. Various cultures have various names for this phenomenon and/or supernatural character.

A neurological explanation suggests that this results from a combination of the threat vigilance activation system and the muscle paralysis associated with sleep paralysis, which removes voluntary control of breathing. 

Several features of REM breathing patterns exacerbate the feeling of suffocation - these include shallow rapid breathing, hypercapnia, and slight blockage of the airway, which is a symptom prevalent in sleep apnea patients. According to this theory, the individual attempts to breathe deeply and finds herself unable to do so, creating a sensation of resistance, which the threat-activated vigilance system interprets as a nightmarish or evil being sitting on her chest, threatening suffocation. The sensation of entrapment causes a feedback loop when the fear of suffocation increases as a result of continued helplessness, causing the subject to struggle to end the sleep paralysis episode. 

The Nightmare (2015) documentary that discusses the causes of sleep paralysis as seen through extensive interviews with participants, and the experiences are re-enacted by professional actors. In synopsis, it proposes that such cultural memes as alien abduction, demonic visitation, the near death experience and shadow people can, in many cases, be attributed to sleep paralysis. There is a further documentary I have watched on the phenomenon of sleep paralysis, called The Entity (2001), although much of the discussion about sleep paralysis was farmed within a Christian context, offering demonic visitation as a explanation for the sleep paralysis experiences of one participant, who was advised - by a priest - to seek salvation in Christ to stop the sleep paralysis. I would have preferred to see a more objective, scientific study of sleep paralysis, given it is a universally-experienced phenomena of sleep which isn't restricted to those who believe in deities or entities.

(3) Vestibular-motor disorientation: OBEs

The intruder and incubus/succubus experiences highly correlate with one another, and moderately correlate with the 3rd characteristic experience - vestibular-motor disorientation, also known as out-of-body experiences (OBEs), which differ from the other 2 sleep paralysis experiences because the OBE does involve the threat-activated vigilance system. 

Under normal conditions, medial and vestibular nuclei, cortical, thalamic, and cerebellar centres coordinate processes such as head and eye movement, and orientation in space. A neurological hypothesis is that in sleep paralysis, these mechanisms - which usually coordinate body movement and provide information on body position - become activated and, because there is no actual movement, induce a floating sensation. The vestibular nuclei in particular has been identified as closely related to dreaming during the REM stage of sleep. 

According to this hypothesis, vestibular-motor disorientation - unlike the intruder and incubus/succubus experiences - arise from completely endogenous sources of stimuli.

Scientific explanations

Physiologically, sleep paralysis is closely related to REM atonia, the paralysis that occurs as a natural part of REM (rapid eye movement) sleep. 

The pathophysiology of sleep paralysis has not been concretely identified, although there are several theories. The first of these is that sleep paralysis is a form of parasomnia which results from a dysfunction – REM sleep overlaps with the waking process. Polysomnographic studies find that individuals who experience sleep paralysis frequently have shorter REM sleep latencies, shorter REM and NREM sleep cycles and greater fragmentation of REM sleep. 

This supports the claim that disturbance of regular sleeping patterns can trigger an episode of sleep paralysis due to the fragmentation of REM sleep. Another major theory is that the neural functions which regulate sleep are out of balance in a way which causes the different states of sleep to overlap. 

In this case, cholinergic sleep on neural populations are hyper activated and the serotonergic sleep off neural populations are under-activated. As a result, the cells capable of sending the signals that would allow for complete arousal from the sleep state (i.e. allowing the individual to wake up), the serotonergic neural populations, have difficulty in overcoming the signals sent by the cells that keep the brain in the sleep state. 

During normal REM sleep, the threshold for a stimulus to cause arousal is greatly elevated. However, in individuals with sleep paralysis, there is almost no blocking of exogenous stimuli, which means it is much easier for a stimulus to arouse the individual to a waking state. 

There may also be a problem with the regulation of melatonin – known as the sleep chemical -which under normal circumstances regulates the serotonergic neural populations. Melatonin is typically at its lowest point during REM sleep. Inhibition of melatonin at an inappropriate time would make it impossible for the sleep off neural populations to depolarize when presented with a stimulus that would normally lead to complete arousal. 

This could explain why the REM and waking stages of sleep overlap during sleep paralysis, and definitely explains the muscle paralysis experienced on awakening. If the effects of sleep on neural populations cannot be counteracted, characteristics of REM sleep are retained upon awakening – hence the dreamlike quality of false awakenings. Common consequences of sleep paralysis includes headaches, muscle pains or weakness and/or paranoia.

Research has found a genetic component in sleep paralysis. The characteristic fragmentation of REM sleep, hypnopompic, and hypnagogic hallucinations also may be inherited, which gives support to the idea that sleep paralysis is also genetic. 

Twin studies have shown that if one twin of a monozygotic pair experiences sleep paralysis that other twin is very likely to experience it as well. The identification of a genetic component means that there is some sort of disruption of function at the physiological level. Further studies must be conducted to determine whether there is a mistake in the signalling pathway for arousal as suggested by the first theory presented, or whether the regulation of melatonin or the neural populations themselves have been disrupted.

Sleep paralysis could also be a part of a larger diagnosis, because of the dissociative state seen during sleep paralysis. Many individuals, especially those who suffer from narcolepsy, seem to have trouble distinguishing between states of wakefulness and sleep - they are unable to tell if what they are experiencing is a dream or if it is reality. Their recall of the experience is very similar to individuals who suffer from delirium, which is why some experts conclude there is a dissociative state in sleep paralysis.

Another possible cause of sleep paralysis is depression. There is a correlation between depression and sleep disturbances - sleep paralysis being one of them. In people that are depressed there is about an 11% frequency of people that have sleep paralysis. The reasoning behind this is the depression causes disturbances in the REM sleep cycle.

Sleep paralysis is mainly diagnosed by ruling out other potential sleep disorders that could account for the feelings of paralysis. The main disorder that is checked for is narcolepsy due to the high prevalence of narcolepsy in conjunction with sleep paralysis. The availability of a genetic test for narcolepsy makes this an easy disorder to rule out. Once all other conditions have been ruled out, the description that the individual gives of their episode is compared to the typical experiences of sleep paralysis that have been well documented.

Several circumstances have been identified that are associated with an increased risk of sleep paralysis. These include insomnia and sleep deprivation, an erratic sleep schedule, stress, overuse of stimulants, physical fatigue, as well as certain medications that are used to treat ADHD. This is in addition to the genetic component which has been identified through the twin studies. 

 Sleeping in the supine position (i.e. on your back) has been found an especially prominent instigator of sleep paralysis. Sleeping on your back is believed to make the sleeper more vulnerable to episodes of sleep paralysis, because in this sleeping position, it is possible for the soft palate to collapse and obstruct the airway. This is a possibility regardless of whether the individual has been diagnosed with sleep apnea or not. There may also be a greater rate of micro-arousals while sleeping in the supine position because there is a greater amount of pressure being exerted on the lungs by gravity.

While many factors can increase risk for sleep paralysis episodes, they can be avoided with minor lifestyle changes – for example, by maintaining a regular sleep schedule and observing good sleep hygiene, one can reduce chances of sleep paralysis. It helps subjects to reduce the intake of stimulants (such as caffeine) and stress in daily life. 

However, some cases of sleep paralysis involve a genetic factor - which means some people may find sleep paralysis unavoidable. If you are attempting to induce lucid dreaming, it may be that you begin to experience sleep paralysis – for the first time, or more frequently than usual. 

Anecdotal reports indicate that wiggling fingers or toes – or moving the eyes from side to side - upon awareness of the condition may enable the sufferer to move again in some cases. Medical treatment starts with education about sleep stages and the inability to move muscles during REM sleep. 

People should be evaluated for narcolepsy if symptoms persist. The safest treatment for sleep paralysis is for people to adopt healthier sleeping habits, however, in serious cases more clinical treatments are available. The most commonly used drugs are tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs), although effectiveness may vary depending on the individual. 

In 2016, Baland Jalal, a neuroscientist from the University of Cambridge, proposed the first direct treatment for sleep paralysis called Meditation-relaxation or MR therapy for sleep paralysis, based on his extensive research on sleep paralysis in several countries. The treatment is partly derived from his 2014 hypothesis, which he researched with the world renowned neuroscientist Vilayanur S Ramachandran. They found that movement during sleep paralysis leads to de-synchronization between motor-execution and feedback from limbs, which can lead to distortions in body image implicating the temporo-parietal junction and right superior parietal lobule. This potentially triggers the hallucinations of shadowy human-like figures (which may in fact be projections of the ‘self’). MR therapy is based on four steps the sleep paralysis experiencer applies during the attack: (1) reappraisal of the meaning of the attack; (2) psychological and emotional distancing; (3) inward focused-attention meditation; (4) Muscle relaxation. Although there are preliminary case reports to support the feasibility and efficacy of this treatment intervention in reducing terrifying hallucinations during sleep paralysis and possibly eliminating the attack, leading to fewer future episodes, the actual feasibility and efficacy of the method must be tested in randomized clinical trials. 

Sleep paralysis poses no immediate risk to those who experience it, despite the fact that it can be an intensely terrifying and confusing experience.

Exercises for lucid dreaming

(1) Experience what hypnagogic imagery looks like

If you have never knowingly experienced hypnagogia before, there is a simple way which you can get a sense of the visual imagery which accompanies this state. Close your eyes and place you hands over them, so no light seeps through. Once your hands are over your eye sockets, open your eyes and focus them on the middle distance - the darkness behind your hands. At first you will probably see the after-glare of light - from your environment, or looking at this digital display. After a few moments this glare will fade and you will see phosphenes - faint visuals which appear as speckles or static, geometric patterns, which intensify when you focus on them. 

(2) Hypnagogic imagery & dream visualisation for WILD

You can try to manipulate your actual hypnagogic imagery for use in lucid dreaming - dream visualisation is a very useful skill to learn. By manipulating your hypnagogic imagery, you can eventually work towards visualising complex dream scenes, which may assist you succeeding in a WILD (Wake-Initiated Lucid Dream).

This is because observing and interacting with your hypnagogic imagery as you fall asleep is the perfect way to enter a lucid dream on demand, taking advantage of the mind-awake/body-asleep state that practitioners of WILD try to recreate. Some people call the WILD technique the 'Hypnagogic Induction Technique' because it involves entering a state of hypnagogia on purpose, then using the visual phenomena as a means of visualising a dream. 

To begin, lay in a dark, silent room. You can do this when you are ready to go to sleep - or better, after you have had your deep sleep (so 4 - 6 hours into a sleep), during a Wake-Back-to-Bed (where you sleep until you have experienced your full quota of deep sleep, then wake temporarily, before going back to sleep and into the long period of REM sleep which occurs at the end of the sleep cycle, just prior to waking). Close your eyes and observe the darkness, but clear your mind of all thoughts. 

To achieve the mind-awake/body-asleep paradox, you need to convince your body that you are ready to fall asleep. Keep your breathing slow and steady and loosen every single muscle in your body. It is best to try this while laying on your back. While you are preparing your body for sleep, you must keep your mind awake and conscious - this can be a tricky balance to achieve as a beginner. 

Try not to move at all. If you feel you have to move - to scratch an itch or relieve tension - do so, and then return back to your still, relaxed position. You may start to feel weightless, as if you are floating. You will start to observe hypnagogic imagery. This may initially appear as phosphenes - speckles or patterns, either in monochrome or colour, which may be static or moving. You can manipulate these to become more complex, figurative/representational images with a little practice. Tell yourself what you want to see and you will begin to visualize the image - this is the process of autosymbolization. 

Once you are able to evolve these images into clear visions, you can start to visualize a lucid dreamscape, which you should try to submerge yourself into. WILD (Wake-Initiated Lucid Dreams) are characterised by the fact you seamlessly transition from the waking state into the lucid dream with no lapse in consciousness. As your dreaming mind takes over, new imagery appears, beyond the field of vision. These visuals may have emotions and memories attached to them. If you manage to remain consciously aware of the process at the point you enter the lucid dream, you have successfully used hypnagogia to induce a WILD dream.

(3) Inducing OBEs & using the OBE-Exit technique for lucid dreaming

There are a number of ways you can experiment with sleep paralysis and hypnagogia as a lucid dreamer. You can either induce an OBE, or if you wake up and find yourself in sleep paralysis (during a false awakening for example) you can try to transform the experience into a full lucid dream using the OBE-exit technique. 

Our scientific understanding of the OBEs strongly suggests that it is a type of dream and a similar phenomenon to WILDs. OBE induction techniques are virtually identical to WILD techniques. An OBE/WILD begins when you're lying down, ideally having recently woken from a sleep or just about to fall asleep. The body then slips back into sleep paralysis (the protective mechanism which prevents us from acting out our dreams) and the body falls asleep. However, unlike in normal sleep, the mind (your conscious awareness) remains awake. 

This means that the conscious mind is aware of the sensation of sleep paralysis – you may feel ‘stuck’ or extremely ‘heavy’ so that you are unable to move. When this occurs, you are already in a dream state, but the sensation of the sleep paralysis, plus the fact your mind is conscious, tricks you into believing you are awake. If you wake up into this state, you might be alerted to the fact that this is a dream because your bedroom has a different appearance, or something seems odd or out of place. If you are inducing this state from wakefulness, you do not lose consciousness at any point, so you are unlikely to experience the same confusion which often accompanies a false awakening. 

Now that you are both mentally awake, but actually asleep – you are lucid dreaming. The experience can be very realistic and vivid. People who believe that they really experience an OBE may refuse to believe that this is really a dream. If they believe the experience is real, it is not a lucid dream – simply a dream they have mistaken for a real OBE. In order to have a lucid dream, you must know ‘I am dreaming’. If you wake into an OBE-like experience (i.e. you experience a false awakening with sleep paralysis and hypnagogia) you should try to ascertain that you are dreaming. You can do this by performing a reality check, or sometimes, by simply looking around at your environment and noticing if there are any clues that you are dreaming, such as changes or oddities.

To fully complete the transition, you must use your mental power (imagination) to swing, roll or float out of your body, which still feels the effects of sleep paralysis. If the sleep paralysis is very strong, you should try to shake or move any part of your body which is capable – usually, even when our entire body is sleep paralysed, we are still able to move our eyes (because REM sleep – where muscle atonia occurs – is characterised by rapid eye movement). Even if all you can do is move your eyes from side to side, try this and imagine all of your muscles loosening and allowing movement, and gradually you will find that you break through the paralysis. 

Sometimes, you may experience the presence of other entities or beings in your environment – as discussed above. Sometimes this can help with the process of lucid dreaming, and at other times it can be problematic. Much of this depends on your own expectations and mental state. You could try closing your eyes and willing these visual hallucinations to go away, trying to remain calm by breathing deeply and reminding yourself that this is a trick of the mind and you are in control. 

It is possible to ‘teleport’ out of your ‘dream body’, directly into a new dream scene or OBE location, by simply visualizing the desired location. This is not a literal teleportation to an actual place, but rather a form of dream travel. Sometimes closing your eyes and imagining you are in a new location is sufficient. Often during the WILD technique, it is possible to bypass the whole experience of going out-of-body by visualizing the lucid dream scene before you start dreaming. With your eyes closed, focus your attention on your hypnagogia and let go of all bodily sensations Many people find this a much smoother transition into a lucid experience. 

An OBE differs from a normal dream in 2 important ways: 

• You have a higher level of consciousness during the experience - The first criteria means that to have an OBE, you must be fully conscious or lucid - you have vivid self-awareness during the experience, and your mental processes and senses are as effective as they are in waking life. This is what makes it so real. In this form, all lucid dreams are a form of OBE. 
• You initiate the experience by exiting your perceived body - The second criteria means being aware of leaving your body while it is lying in bed. Normally your dreams just launch off in a new dream environment. However, in an OBE you begin the process lying in bed, in same position as your physical body. In this form, only certain types of wake-induced lucid dreams constitute an out of body experience.

I will now explain how you can induce your own OBE in 3 simple steps 

Step 1 - Relax your Mind & Body

The best time to try this is around 5 - 7am, after you've have some good quality deep sleep, but are still tired enough to drop off again into the prolonged period of REM sleep which normally occurs at the end of the sleep cycle, just prior to waking. 

Lay in a comfortable position (on your back is the best option). Take some slow, controlled breaths and allow your eyes to close naturally. Try not to think about anything – clear your mind and ignore any intrusive or distracting thoughts which may pop into your mind. 

Start your meditation routine. Beginners will find it helpful to listen to brainwave entrainment (binaural beats) on headphones, as this removes thought distractions and stimulates more relaxed states of awareness. The initial goal is to clear and focus your mind, maintaining its conscious awareness, while your body falls asleep. 

Perform your systematic relaxation routine. Starting from your toes, tighten and then relax every muscle group in your body. Imagine them sinking into the bed or floating up and becoming weightless or simply going invisible. Finish by fully relaxing your face, jaw and neck where you hold most tension. Use circular breathing – inhale deeply through the nose and exhale through the mouth, in a regular pattern. 

Within 5 - 10 minutes you should feel relaxed and dreamy, with greatly reduced awareness of your body. You may begin to feel floating limbs or that your arms are in different positions than they were previously. 

Step 2 - Shift your Awareness from your Physical Body

When you have little bodily sensation left, shift your awareness away from your body and gaze into the black space in front of your eyes. Visualize your own mental imagery or follow your natural hypnagogia. As you go deeper, be aware of the images arising in your mind's eye, beyond your field of vision. This process is known as ‘falling asleep consciously’ - You are tricking your body into thinking you have gone to sleep when in fact your mind remains awake. 

At this stage you may feel the effects of sleep paralysis. As your mind wanders further into the blackness, you may be startled by a loud vibrating or humming noise inside your head. This is just another phase in the OBE process – the best thing to do is to simply ignore it. 

Step 3 - Move out of your Physical Body

The vibrations soon pass and once that happens, you will be set free into your dream world. You may find you already have an arm or leg free, are fully floating above your body in bed, or that you've rolled across the bed and fallen onto the floor. If you have not already left your body, imagine that you are able to do so using your intention and will-power to force yourself out of your body. There is no danger - your real body is lying in bed sleeping peacefully. This early movement can be very confusing, but stay focused or you may wake up. If you find you are still ‘stuck’ in your body, remember that you are now in a lucid dream world, where your thoughts become extremely powerful and control all your movement. Use one of the following methods to leave your ‘paralyzed’ body: 

• Float out - visualize your viewpoint has risen a few feet into the air 
• Swing out - visualize a swing forming long arcs as you gain momentum 
• Sink out - imagine your dream body slowly dropping through the bed 
• Roll out - visualize yourself turning on your side and rolling over 
• Teleport out - imagine another location and engage your senses 

You will naturally regain your vision when your awareness moves out of body. If your vision is blurry or unclear, demand that you have better clarity by telling yourself: ‘Clarity!’ Try and focus your attention on small details of your environment. This can also help you draw the right conclusion as to whether you are awake or dreaming if you are still in any doubt.