View source for Sleep paralysis

{{Short description|Sleeping disorder}}
{{cs1 config|name-list-style=vanc}}
{{For|the normal sleep behavior of body paralysis during dreams|Rapid eye movement sleep}}
{{redirect|Night demon|the American heavy metal band|Night Demon (band)}}
{{Infobox medical condition (new)
| name          = Sleep paralysis
| image         = File:Henry Fuseli (1741–1825), The Nightmare, 1781.jpg
| alt           = 
| caption       = ''[[The Nightmare]]'' by Swiss artist [[Henry Fuseli]] (1781) is thought to be a depiction of sleep paralysis perceived as a [[demon]]ic visitation.
| field         = {{Flatlist|
*[[Psychiatry]]
*[[sleep medicine]]
}}
| symptoms      = {{Flatlist|
*Awareness but an inability to move during waking or falling asleep
*hallucinations<ref name=Sharp2016/><ref name=Av2011/>
}}
| complications = [[Nyctophobia]]
| onset         = 
| duration      = No more than a couple of minutes<ref name=Av2011/>
| causes        = 
| risks         = {{Flatlist|
*[[Narcolepsy]]
*[[obstructive sleep apnea]]
*alcohol use
*[[sleep deprivation]]<ref name=Sharp2016/><ref name=Av2011/>
}}
| diagnosis     = Based on description<ref name=Av2011/>
| differential  = {{Flatlist|
*[[Narcolepsy]]
*[[atonic seizure]]
*[[hypokalemic periodic paralysis]]
*[[night terror]]<ref name=Sharp2016/><ref name=Av2011/>
}}
| prevention    = 
| treatment     = {{Flatlist|
*Reassurance
*[[sleep hygiene]]
*[[cognitive behavioral therapy]]
*[[antidepressants]]<ref name=Sharp2016/>
}}
| medication    = 
| prognosis     = 
| frequency     = 8–50%<ref name=Av2011/>
| deaths        = None; physically harmless<ref name=":11" />
}}

<!-- Definition and symptoms -->
'''Sleep paralysis''' is a state, [[hypnopompic|during waking up]] or [[hypnagogic|falling asleep]], in which a person is conscious but in a complete state of full-body [[paralysis]].<ref name=Sharp2016>{{cite journal|last1=Sharpless|first1=BA|title=A clinician's guide to recurrent isolated sleep paralysis.|journal=Neuropsychiatric Disease and Treatment|date=2016|volume=12|pages=1761–67|doi=10.2147/NDT.S100307|pmid=27486325|pmc=4958367 |doi-access=free }}</ref><ref name=Av2011>{{cite book|last1=Avidan|first1=Alon Y.|last2=Zee|first2=Phyllis C.|title=Handbook of Sleep Medicine|date=2011|publisher=Lippincott Williams & Wilkins|isbn=978-1-4511-5385-9|page=Chapter 5|edition=2nd|url=https://books.google.com/books?id=D66s7fxc-0cC&pg=PT113|language=en}}</ref> During an episode, the person may [[hallucination|hallucinate]] (hear, feel, or see things that are not there), which often results in [[fear]].<ref name=Sharp2016/><ref name=":11">{{cite web |date=2017-10-23 |title=Sleep paralysis |url=https://www.nhs.uk/conditions/sleep-paralysis/ |access-date=2023-02-06 |website=nhs.uk |language=en}}</ref> Episodes generally last no more than a few minutes.<ref name=Av2011/> It can recur multiple times or occur as a single episode.<ref name=Sharp2016/><ref name=":11" />

<!-- Cause -->
The condition may occur in those who are otherwise healthy or those with [[narcolepsy]], or it may run in families as a result of specific [[genetics|genetic]] changes. The condition can be triggered by [[sleep deprivation]], [[psychological stress]], or abnormal [[sleep cycles]]. The underlying mechanism is believed to involve a dysfunction in [[REM sleep]].<ref name="Av2011" /> Diagnosis is based on a person's description. Other conditions that can present similarly include narcolepsy, [[atonic seizure]], and [[hypokalemic periodic paralysis]].<ref name=Av2011/>
<!-- Treatments -->
Treatment options for sleep paralysis have been poorly studied. It is recommended that people be reassured that the condition is common and generally not serious. Other efforts that may be tried include [[sleep hygiene]], [[cognitive behavioral therapy]], and [[antidepressants]].<ref name=Sharp2016/>

<!-- Epidemiology and history -->
Between 8% to 50% of people experience sleep paralysis at some point during their lifetime.<ref name=Av2011 /><ref name=Bri2011>{{cite journal|last1=Sharpless|first1=Brian A.|last2=Barber|first2=Jacques P.|title=Lifetime prevalence rates of sleep paralysis: A systematic review|journal=Sleep Medicine Reviews|date=October 2011|volume=15|issue=5|pages=311–315|doi=10.1016/j.smrv.2011.01.007|pmid=21571556|pmc=3156892}}</ref> About 5% of people have regular episodes. Males and females are affected equally.<ref name=Av2011/> Sleep paralysis has been described throughout history. It is believed to have played a role in the creation of stories about [[alien abduction]] and other [[paranormal]] events.<ref name=Sharp2016/>

== Symptoms and signs==
The main symptom of sleep paralysis is being unable to move or speak during waking.<ref name=Sharp2016/>

Imagined sounds such as [[humming]], [[Noise (electronics)|hissing]], [[White noise|static]], [[Electrostatic discharge|zapping]] and buzzing noises are reported during sleep paralysis.<ref>Thorpy, M.J. (ed.). (1990). ''{{'}}Sleep paralysis'. l Classification of Sleep Disorders: Diagnostic and Coding Manual''. Rochester, Minn.: American Sleep Disorders Association.</ref> Other sounds such as [[voice]]s, [[whisper]]s and [[roaring|roars]] are also experienced. It has also been known that one may feel pressure on their chest and intense pain in their head during an episode.<ref>{{cite journal | author = Spanos N.P., McNulty S.A., DuBreuil S.C., Pires M. | year = 1995 | title = The frequency and correlates of sleep paralysis in a university sample | journal = Journal of Research in Personality | volume = 29 | issue = 3| pages = 285–305 | doi=10.1006/jrpe.1995.1017}}</ref> These symptoms are usually accompanied by intense [[emotion]]s such as [[fear]] and [[panic]].<ref name=Blackmore2002 /> People also have feelings of drowning or sinking, being dragged out of bed or of flying, [[numbness]], and feelings of electric [[Paresthesia|tingles]] or [[vibration]]s running through their body.<ref name="Cheyneninenine">{{cite journal |last1=Cheyne |first1=J. |last2=Rueffer |first2=S. |last3=Newby-Clark |first3=I. |year=1999 |title=Hypnagogic and Hypnopompic Hallucinations during Sleep Paralysis: Neurological and Cultural Construction of the Night-Mare |journal=Consciousness and Cognition |volume=8 |issue=3 |pages=319–337 |doi=10.1006/ccog.1999.0404 |pmid=10487786 |s2cid=23758148}}</ref>

Sleep paralysis may include hallucinations, such as an intruding presence or dark figure in the room. These are commonly known as ''sleep paralysis demons''. It may also include the inability to breathe or the individual feeling a sense of terror, accompanied by a feeling of pressure on one's chest and [[Shortness of breath|difficulty breathing]].<ref name=":1">{{cite journal|last1=Jalal|first1=Baland|last2=Romanelli|first2=Andrea|last3=Hinton|first3=Devon E.|date=2015-12-01|title=Cultural Explanations of Sleep Paralysis in Italy: The Pandafeche Attack and Associated Supernatural Beliefs|journal=Culture, Medicine and Psychiatry|volume=39|issue=4|pages=651–664|doi=10.1007/s11013-015-9442-y|issn=1573-076X|pmid=25802016|s2cid=46090345}}</ref>

== Pathophysiology ==
The pathophysiology of sleep paralysis has not been concretely identified, although there are several theories about its cause.<ref name=":0">{{cite book|title=Unusual and rare psychological disorders: a handbook for clinical practice and research|last=A.|first=Sharpless, Brian|isbn=978-0-19-024586-3|oclc=952152912|date = 2016-11-15|publisher=Oxford University Press }}</ref> The first of these stems from the understanding that sleep paralysis is a [[parasomnia]] resulting from dysfunctional overlap of the REM and waking stages of sleep.<ref name=Goldstein>{{cite journal|last=Goldstein |first=K. |title=Parasomnias|journal=Disease-a-Month|year=2011|volume=57 |pages=364–88|doi=10.1016/j.disamonth.2011.04.007 |pmid=21807161 |issue=7}}</ref> [[Polysomnography|Polysomnographic]] studies have found that individuals who experience sleep paralysis have shorter REM sleep latencies than normal along with shortened NREM and REM sleep cycles, and fragmentation of REM sleep. This study supports the observation that disturbance of regular sleeping patterns can precipitate an episode of sleep paralysis, because fragmentation of REM sleep commonly occurs when sleep patterns are disrupted and has now been seen in combination with sleep paralysis.<ref name="Walther">{{cite journal |last1=Walther |first1=B. |last2=Schulz |first2=H. |year=2004 |title=Recurrent isolated sleep paralysis: Polysomnographic and clinical findings |journal=Somnologie – Schlafforschung und Schlafmedizin |volume=8 |issue=2 |pages=53–60 |doi=10.1111/j.1439-054X.2004.00017.x |s2cid=143146512}}</ref>

Another major theory is that the neural functions that regulate sleep are out of balance, causing different sleep states to overlap. In this case, cholinergic sleep "on" [[neural population]]s are hyperactivated 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, 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. Under normal conditions, medial and [[vestibular nuclei]], [[Cortex (anatomy)|cortical]], [[thalamic]], and [[cerebellar]] centers coordinate things such as head and eye movement, and orientation in space.<ref name=Cheyneninenine />

In individuals reporting sleep paralysis, there is almost no blocking of exogenous stimuli, which means it is much easier for a stimulus to arouse the individual. The vestibular nuclei in particular has been identified as being closely related to dreaming during the REM stage of sleep.<ref name=Cheyneninenine /> According to this hypothesis, vestibular-motor disorientation, unlike hallucinations, arise from completely endogenous sources of stimuli.<ref name="Cheynetwothree">{{cite journal |last=Cheyne |first=J. |year=2003 |title=Sleep Paralysis and the Structure of Waking-Nightmare Hallucinations |journal=[[Dreaming (journal)|Dreaming]] |volume=13 |issue=3 |pages=163–179 |doi=10.1023/A:1025373412722 |s2cid=145006406}}</ref>

If the effects of sleep "on" neural populations cannot be counteracted, characteristics of REM sleep are retained upon awakening. Common consequences of sleep paralysis include headaches, muscle pains or weakness or paranoia. 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 unable to speak.<ref>Hearne, K. (1990). ''The Dream Machine: Lucid dreams and how to control them'', p. 18. {{ISBN|0-85030-906-9}}.</ref>

Research has found a genetic component in sleep paralysis.<ref>(Sehgal 2011)</ref> The characteristic fragmentation of REM sleep, [[hypnopompic]], and [[Hypnagogia|hypnagogic]] hallucinations have a heritable component in other parasomnias, which lends credence to the idea that sleep paralysis is also genetic. Twin studies have shown that if one twin of a monozygotic pair ([[Twin#Monozygotic (identical) twins|identical twins]]) experiences sleep paralysis that the other twin is very likely to experience it as well.<ref name="Sehgal">{{cite journal |last1=Sehgal |first1=A. |last2=Mignot |first2=E. |year=2011 |title=Genetics of Sleep and Sleep Disorders |journal=Cell |volume=146 |issue=2 |pages=194–207 |doi=10.1016/j.cell.2011.07.004 |pmc=3153991 |pmid=21784243}}</ref> The identification of a genetic component means that there is some sort of disruption of a function at the physiological level. Further studies must be conducted to determine whether there is a mistake in the signaling pathway for arousal as suggested by the first theory presented, or whether the regulation of melatonin or the neural populations themselves have been disrupted.

===Hallucinations===
[[File:Fritz Schwimbeck - My Dream, My Bad Dream. 1915.jpg|thumb|upright=1.3|A picture of a [[succubus]]-like vision. ''My Dream, My Bad Dream'', 1915, by Fritz Schwimbeck]]

Several types of hallucinations have been linked to sleep paralysis: the belief that there is an intruder in the room, the feeling of a presence, and the sensation of floating. One common hallucination is the presence of an [[incubus]]. A neurological hypothesis is that in sleep paralysis the [[cerebellum]], which usually coordinates body movement and provides information on body position, experiences a brief myoclonic spike in brain activity inducing a [[floating (psychological phenomenon)|floating]] sensation.<ref name=Cheynetwothree />

The [[trespasser|intruder]] and incubus hallucinations highly correlate with one another, and moderately correlated with the third hallucination, vestibular-motor disorientation, also known as [[out-of-body experience]]s,<ref name=Cheynetwothree /> which differ from the other two in not involving the threat-activated vigilance system.<ref name=FISP />

=== Threat hyper-vigilance ===
A [[Hypervigilance|hyper-vigilant]] state created in the [[midbrain]] may further contribute to hallucinations.<ref name="Cheyneninenine" /> 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. The threat-activated vigilance system is a protective mechanism that differentiates between dangerous situations and determines whether the fear response is appropriate.<ref name="Cheynetwothree" />

The hyper-vigilance response can lead to the creation of endogenous stimuli that contribute to the perceived threat.<ref name=Cheyneninenine /> A similar process may explain hallucinations, with slight variations, in which an evil presence is perceived by the subject to be attempting to suffocate them, either by pressing heavily on the chest or by strangulation. A neurological explanation holds that this results from a combination of the threat vigilance activation system and the muscle paralysis associated with sleep paralysis that removes voluntary control of breathing. Several features of REM breathing patterns exacerbate the feeling of suffocation.<ref name=Cheynetwothree /> These include shallow rapid breathing, [[hypercapnia]], and slight blockage of the airway, which is a symptom prevalent in [[sleep apnea]] patients.<ref name=Cheyneninenine />

According to this account, the subjects attempt to breathe deeply and find themselves unable to do so, creating a sensation of resistance, which the threat-activated vigilance system interprets as an unearthly being sitting on their chest, threatening suffocation.<ref name=Cheyneninenine /> The sensation of entrapment causes a feedback loop when the fear of suffocation increases as a result of continued helplessness, causing the subjects to struggle to end the SP episode.<ref name=Cheynetwothree />

== Diagnosis ==
Sleep paralysis is mainly diagnosed via clinical interview and ruling out other potential [[sleep disorder]]s that could account for the feelings of paralysis.<ref name=":0" /><ref name=Goldstein /> Several measures are available to reliably diagnose<ref name="FISP" /><ref name=":7">{{cite book|title=Sleep Paralysis: Historical, Psychological, and Medical Perspectives|last=Sharpless, B., and Doghramji, K|publisher=Oxford University Press.|year=2015}}</ref> or screen (''Munich Parasomnia Screening'')<ref>{{cite journal|last1=Fulda|first1=Stephany|last2=Hornyak|first2=Magdolna|last3=Müller|first3=Karin|last4=Cerny|first4=Lukas|last5=Beitinger|first5=Pierre A.|last6=Wetter|first6=Thomas C.|date=2008-03-01|title=Development and validation of the Munich Parasomnia Screening (MUPS)|journal=Somnologie - Schlafforschung und Schlafmedizin|language=en|volume=12|issue=1|pages=56–65|doi=10.1007/s11818-008-0336-x|issn=1432-9123|doi-access=free}}</ref> for recurrent isolated sleep paralysis.

===Diagnosis===
Episodes of sleep paralysis can occur in the context of several medical conditions (e.g., narcolepsy, [[hypokalemia]]). When episodes occur independent of these conditions or substance use, it is termed "isolated sleep paralysis" (ISP).<ref name=":7" /> When ISP episodes are more frequent and cause clinically significant distress or interference, it is classified as "recurrent isolated sleep paralysis" (RISP). Episodes of sleep paralysis, regardless of classification, are generally short (1–6 minutes), but longer episodes also have been documented.<ref name="Cheyneninenine" />

It can be difficult to differentiate between [[cataplexy]] brought on by narcolepsy and true sleep paralysis, because the two phenomena are physically indistinguishable. The best way to differentiate between the two is to note when the attacks occur most often. Narcolepsy attacks are more common when the individual is falling asleep; ISP and RISP attacks are more common upon awakening.<ref name=FISP>{{cite journal |last1=Sharpless |first1=B. |last2=McCarthy|first2=K.|last3=Chambless|first3=D. |last4=Milrod|first4=B. |last5=Khalsa |first5=S. |last6=Barber |first6=J. |title=Isolated sleep paralysis and fearful isolated sleep paralysis in outpatients with panic attacks |journal=Journal of Clinical Psychology |year=2010 |volume=66|pages=1292–1306 |doi=10.1002/jclp.20724 |pmid=20715166 |issue=12 |pmc=3624974}}</ref>

===Differential diagnoses===

Similar conditions include:<ref name="Sharp2015">{{cite book |last1=Sharpless |first1=Brian A. |last2=Doghramji |first2=Karl |title=Sleep Paralysis: Historical, Psychological, and Medical Perspectives |date=2015 |publisher=Oxford University Press |isbn=978-0-19-931380-8 |pages=170–181 |url=https://books.google.com/books?id=DNymCAAAQBAJ&pg=PP1 |language=en}}</ref>
* [[Exploding head syndrome]] (EHS) potentially frightening parasomnia, the hallucinations are usually briefer and always loud or jarring. There is no paralysis during EHS.
* [[Nightmare disorder]] (ND); also REM-based parasomnia.
* [[Sleep terrors]] (STs) are potentially frightening parasomnia, but are not REM based and there is a lack of awareness to surroundings, characteristic screams during STs.
* [[Noctural panic attacks]] (NPAs) involve fear and acute distress but lack paralysis and dream imagery.
* [[Post-traumatic stress disorder]] (PTSD) often includes scary imagery and anxiety but not limited to sleep-wake transitions.

== Prevention ==
Several circumstances have been identified that are associated with an increased risk of sleep paralysis. These include [[insomnia]], [[sleep deprivation]], an erratic sleep schedule, [[Stress (biology)|stress]], and physical fatigue. It is also believed that there may be a genetic component in the development of RISP, because there is a high concurrent incidence of sleep paralysis in [[monozygotic twins]].<ref name=Sehgal /> Sleeping in the [[supine position]] has been found an especially prominent instigator of sleep paralysis.<ref name=":1" /><ref name=Cheynetwotwo>{{cite journal |last=Cheyne |first=J. |title=Situational factors affecting sleep paralysis and associated hallucinations: position and timing effects |journal=Journal of Sleep Research|year=2002|volume=11 |pages=169–177 |doi=10.1046/j.1365-2869.2002.00297.x |pmid=12028482 |issue=2|s2cid=37037694 |doi-access=free }}</ref>

Sleeping in the supine position 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 microarousals while sleeping in the supine position because there is a greater amount of pressure being exerted on the lungs due to gravity.<ref name=Cheynetwotwo />

While many factors can increase the risk for ISP or RISP, they can be avoided with minor lifestyle changes.<ref name=Goldstein />

== Treatment ==
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.<ref>Wills L, Garcia J. Parasomnias: Epidemiology and Management. CNS Drugs [serial online]. December 2002;16(12):803–810.</ref> The safest treatment for sleep paralysis is for people to adopt healthier sleeping habits. However, in more serious cases [[tricyclic antidepressants]] or [[selective serotonin reuptake inhibitors]] (SSRIs) may be used. Most people tend to overcome sleep paralysis by being woken up through touch or movement.<ref>{{Cite book |last=Judd |first=Sandra |title=Sleep Disorders Sourcebook |publisher=Peter E. Ruffner |year=2010 |isbn=978-0-7808-1084-6 |edition=3rd}}</ref> Despite the fact that these treatments are prescribed, there is currently no drug that has been found to completely interrupt episodes of sleep paralysis the majority of the time.<ref name="Med">{{cite journal |last=Stores |first=G. |year=2003 |title=Medication for sleep-wake disorders |journal=Archives of Disease in Childhood |volume=88 |issue=10 |pages=899–903 |doi=10.1136/adc.88.10.899 |pmc=1719336 |pmid=14500311}}</ref> 

=== Medications ===
Though no large trials have taken place which focus on the treatment of sleep paralysis, several drugs have promise in case studies. Two trials of [[gamma-Hydroxybutyric acid|GHB]] for people with narcolepsy demonstrated reductions in sleep paralysis episodes.<ref name=":4">{{cite journal |last=Sharpless |first=Brian |date=2016-07-19 |title=A clinician's guide to recurrent isolated sleep paralysis |journal=Neuropsychiatric Disease and Treatment |language=en |volume=12 |pages=1761–1767 |doi=10.2147/ndt.s100307 |pmc=4958367 |pmid=27486325 |doi-access=free}}</ref> 

[[Pimavanserin]] has been proposed as a possible candidate for future studies in treating sleep paralysis.<ref name="newrev2018">{{cite journal | author = Baland Jalal | year = 2018 | title = The neuropharmacology of sleep paralysis hallucinations: serotonin 2A activation and a novel therapeutic drug | journal = Psychopharmacology (Berl) | volume = 235 | issue = 11| pages = 3083–3091 | doi= 10.1007/s00213-018-5042-1 | pmid = 30288594| pmc = 6208952 | doi-access = free }}</ref>

=== Cognitive-behavior therapy ===
Some of the earliest work in treating sleep paralysis was done using a [[Cognitive behavioral therapy|cognitive-behavior therapy]] called CA-CBT. The work focuses on psycho-education and modifying catastrophic cognitions about the sleep paralysis attack.<ref>{{cite journal|last1=Hinton|first1=Devon E.|last2=Pich|first2=Vuth|last3=Chhean|first3=Dara|last4=Pollack|first4=Mark H.|last5=McNally|first5=Richard J.|date=2005|title=Sleep paralysis among Cambodian refugees: association with PTSD diagnosis and severity|journal=Depression and Anxiety|volume=22|issue=2|pages=47–51|doi=10.1002/da.20084|issn=1091-4269|pmid=16094659|s2cid=36056163|doi-access=}}</ref><ref>{{cite journal|last1=Hinton|first1=Devon E.|last2=Pich|first2=Vuth|last3=Chhean|first3=Dara|last4=Pollack|first4=Mark H.|date=2005-03-01|title='The ghost pushes you down': sleep paralysis-type panic attacks in a Khmer refugee population|url=https://www.ncbi.nlm.nih.gov/pubmed?Db=pubmed&Cmd=ShowDetailView&TermToSearch=15881268|journal=Transcultural Psychiatry|volume=42|issue=1|pages=46–77|doi=10.1177/1363461505050710|issn=1363-4615|pmid=15881268|s2cid=35609685|url-status=live|archive-url=https://web.archive.org/web/20170708211341/https://www.ncbi.nlm.nih.gov/pubmed?db=PubMed|archive-date=2017-07-08}}</ref> This approach has previously been used to treat sleep paralysis in Egypt, although clinical trials are lacking.<ref>{{cite journal|last1=Jalal|first1=Baland|last2=Samir|first2=Sherine W.|last3=Hinton|first3=Devon E.|date=2017-02-01|title=Adaptation of CBT for Traumatized Egyptians: Examples from Culturally Adapted CBT (CA-CBT)|journal=Cognitive and Behavioral Practice|volume=24|issue=1|pages=58–71|doi=10.1016/j.cbpra.2016.03.001}}</ref>

The first published psychosocial treatment for recurrent isolated sleep paralysis was cognitive-behavior therapy - isolated sleep paralysis (CBT-ISP).<ref name=":7" /> It begins with self-monitoring of symptoms, cognitive restructuring of maladaptive thoughts relevant to ISP (e.g., "the paralysis will be permanent"), and psychoeducation about the nature of sleep paralysis. Prevention techniques include ISP-specific sleep hygiene and the preparatory use of various relaxation techniques (e.g. diaphragmatic breathing, mindfulness, progressive muscle relaxation, meditation). Episode disruption techniques<ref name=":5">{{cite journal|last1=Sharpless|first1=Brian Andrew|last2=Grom|first2=Jessica Lynn|date=2016-03-03|title=Isolated Sleep Paralysis: Fear, Prevention, and Disruption|journal=Behavioral Sleep Medicine|volume=14|issue=2|pages=134–139|doi=10.1080/15402002.2014.963583|issn=1540-2002|pmid=25315810|s2cid=38450571}}</ref> are first practiced in session and then applied during actual attacks. No controlled trial of CBT-ISP has yet been conducted to prove its effectiveness.

== Epidemiology ==
Sleep paralysis is experienced equally in males and females.<ref name=Bri2011 /><ref name=Dauvilliers>{{cite journal|last1=Dauvilliers |first1=Y. |last2=Billiard|first2=M. |last3=Montplaisir|first3=J.|title=Clinical aspects and pathophysiology of narcolepsy |journal=Clinical Neurophysiology|year=2003 |volume=114 |pages=2000–2017 |doi=10.1016/S1388-2457(03)00203-7 |pmid=14580598|issue=11|s2cid=45340130 }}</ref> Lifetime prevalence rates derived from 35 aggregated studies indicate that approximately 8% of the general population, 28% of students, and 32% of psychiatric patients experience at least one episode of sleep paralysis at some point in their lives.<ref name=Bri2011 /> Rates of recurrent sleep paralysis are not as well known, but 15–45% of those with a lifetime history of sleep paralysis may meet diagnostic criteria for Recurrent Isolated Sleep Paralysis.<ref name="FISP" /><ref name=":0" /> In surveys from Canada, China, England, Japan and Nigeria, 20% to 60% of individuals reported having experienced sleep paralysis at least once in their lifetime.<ref name=Blackmore2002>{{cite journal | author = Blackmore Susan J., Parker Jennifer J. | year = 2002 | title = Comparing the Content of Sleep Paralysis and Dream Reports | journal = Dreaming | volume = 12 | issue = 1 | pages = 45–59 | doi = 10.1023/A:1013894522583 | s2cid = 143952687 | url = http://www.susanblackmore.co.uk/Articles/PDFs/Dreaming%202002.pdf | url-status = live | archive-url = https://web.archive.org/web/20160429025711/http://www.susanblackmore.co.uk/Articles/PDFs/Dreaming%202002.pdf | archive-date = 2016-04-29 }}</ref> In general, non-whites appear to experience sleep paralysis at higher rates than whites, but the magnitude of the difference is rather small.<ref name=Bri2011 /> Approximately 36% of the general population that experiences isolated sleep paralysis, develop it between 25 and 44 years of age.<ref name=Ohayon>{{cite journal |last1=Ohayon|first1=M. |last2=Zulley|first2=J. |last3=Guilleminault|first3=C. |last4=Smirne|first4=S. |title=Prevalence and pathologic associations of sleep paralysis in the general population |journal=Neurology |year=1999 |volume=52 |pages=1194–2000 |doi=10.1212/WNL.52.6.1194 |pmid=10214743 |issue=6|s2cid=22288238 }}</ref>

Isolated sleep paralysis is commonly seen in patients that have been diagnosed with narcolepsy. Approximately 30–50% of people that have been diagnosed with narcolepsy, have experienced sleep paralysis as an auxiliary symptom. A majority of the individuals who have experienced sleep paralysis, have sporadic episodes that occur once a month to once a year. Only 3% of individuals who experience sleep paralysis that is not associated with a [[neuromuscular disorder]] have nightly episodes.<ref name=Ohayon />

== Society and culture ==
=== Etymology ===
[[File:Der Albtraum (Anonym 19 Jh).jpg|thumb|230px|A 19th century version of ''[[Henry Fuseli|Füssli's]] The Nightmare'' (1781)]]
The original definition of sleep paralysis was codified by [[Samuel Johnson]] in his ''[[A Dictionary of the English Language]]'' as ''[[nightmare]]'', a term that evolved into the modern definition. The term was first used and dubbed by British neurologist, [[Samuel Alexander Kinnier Wilson|S.A.K. Wilson]] in his 1928 dissertation, ''The Narcolepsies.''<ref>Wilson S. A. K. (1928). The narcolepsies. ''Brain'' 51 63–109. 10.1093/brain/51.1.63</ref> Such sleep paralysis was widely considered the work of [[demon]]s, and more specifically [[Incubus|incubi]], which were thought to sit on the chests of sleepers. In [[Old English language|Old English]], the name for these beings was ''mare'' or ''mære'' (from a [[proto-Germanic language|proto-Germanic]] ''*marōn'', cf. [[Old Norse language|Old Norse]] ''[[mara (folklore)|mara]]''), hence comes the ''mare'' in the word ''nightmare''. The word might be [[cognate]] to [[Ancient Greek|Greek]] ''Marōn'' (in the [[Odyssey]]) and [[Sanskrit]] ''[[Mara (demon)|Māra]]''.

=== Cultural significance and priming ===
[[File:Augustins - Cauchemar - Eugène Thivier - RI 1156.jpg|thumb|230px|''Le Cauchemar'' (''The Nightmare''), by Eugène Thivier (1894)]]Although the core features of sleep paralysis (e.g., atonia, a clear sensorium, and frequent hallucinations) appear to be universal, the ways in which they are experienced vary according to time, place, and culture.<ref name=":1" /><ref name=":2">{{cite journal|last1=Jalal|first1=Baland|last2=Simons-Rudolph|first2=Joseph|last3=Jalal|first3=Bamo|last4=Hinton|first4=Devon E.|date=2014-04-01|title=Explanations of sleep paralysis among Egyptian college students and the general population in Egypt and Denmark|journal=Transcultural Psychiatry|volume=51|issue=2|pages=158–175|doi=10.1177/1363461513503378|issn=1461-7471|pmid=24084761|s2cid=22226921}}</ref> Over 100 terms have been identified for these experiences.<ref name=":7" /> Some scientists have proposed sleep paralysis as an explanation for reports of paranormal and spiritual phenomena such as [[ghost]]s,<ref name=":8">{{cite book|title=The terror that comes in the night : an experience-centered study of supernatural assault traditions / monograph.|last=David.|first=Hufford|publisher=University of Pennsylvania Press|isbn=978-0-8122-1305-8|oclc=862147963|date = September 1989}}</ref><ref name=":3">{{cite journal|last1=Hinton|first1=Devon E.|last2=Pich|first2=Vuth|last3=Chhean|first3=Dara|last4=Pollack|first4=Mark H.|date=2005-03-01|title='The Ghost Pushes You Down': Sleep Paralysis-Type Panic Attacks in a Khmer Refugee Population|journal=Transcultural Psychiatry|language=en|volume=42|issue=1|pages=46–77|doi=10.1177/1363461505050710|issn=1363-4615|pmid=15881268|s2cid=35609685}}</ref> alien visits,<ref>Blackmore, Susan. (1998) [http://www.csicop.org/si/show/abduction_by_aliens_or_sleep_paralysis "Abduction by Aliens or Sleep Paralysis?"] {{webarchive|url=https://web.archive.org/web/20100813121544/http://www.csicop.org/si/show/abduction_by_aliens_or_sleep_paralysis |date=2010-08-13 }}. ''Skeptical Inquirer'', May/June 1998. (Retrieved 13 May 2014)</ref> [[demons]] or [[demonic possession]],<ref name=":1" /><ref name=":6" /> [[alien abduction]] experiences,<ref name="pmid15881271">{{cite journal |vauthors=McNally RJ, Clancy SA |title=Sleep Paralysis, Sexual Abuse, and Space Alien Abduction |journal=[[Transcultural Psychiatry]] |volume=42 |issue=1 |pages=113–122 |year=2005|pmid=15881271 |doi=10.1177/1363461505050715|s2cid=9569785 }}</ref><ref name="Cordon2005-8">{{cite book|title=Popular Psychology: An Encyclopedia|first=Luis A.|last=Cordón|publisher=Greenwood Publishing Group|year=2005|isbn=978-0-313-32457-4|page=[https://archive.org/details/popularpsycholog0000cord/page/8 8]|section=Alien abduction|url=https://archive.org/details/popularpsycholog0000cord|url-access=registration}}</ref> the [[night hag]] and [[shadow people]] haunting.<ref name=":0" /><ref name="Cheynetwothree" />

According to some scientists, culture may be a major factor in shaping sleep paralysis.<ref name=":6">{{cite journal|last1=Jalal|first1=Baland|last2=Hinton|first2=Devon E.|date=2013-07-25|title=Rates and Characteristics of Sleep Paralysis in the General Population of Denmark and Egypt|journal=Culture, Medicine, and Psychiatry|language=en|volume=37|issue=3|pages=534–548|doi=10.1007/s11013-013-9327-x|pmid=23884906|s2cid=28563727|issn=0165-005X}}</ref> When sleep paralysis is interpreted through a particular cultural filter, it may take on greater salience. For example, if sleep paralysis is feared in a certain culture, this fear could lead to conditioned fear, and thus worsen the experience, in turn leading to higher rates.<ref name=":1" /><ref name=":6" /> Consistent with this idea, high rates and long durations of immobility during sleep paralysis have been found in Egypt, where there are elaborate beliefs about sleep paralysis, involving [[malevolent spirit]]-like creatures, the ''[[jinn]].''<ref name=":6" />

Research has found that sleep paralysis is associated with great fear and fear of impending death in 50% of sufferers in Egypt. A study comparing rates and characteristics of sleep paralysis in Egypt and Denmark found that the phenomenon is three times more common in Egypt than Denmark.<ref name=":6" /> In Denmark, unlike Egypt, there are no elaborate supernatural beliefs about sleep paralysis, and the experience is often interpreted as an odd physiological event, with overall shorter sleep paralysis episodes and fewer people (17%) fearing that they could die from it.<ref name=":2" />

=== Folklore ===
{{main|Night hag}}
The [[night hag]] is a generic name for a folkloric creature found in cultures around the world, and which is used to explain the phenomenon of sleep paralysis. A common description is that a person feels the presence of a supernatural malevolent being which immobilizes the person as if standing on the chest.<ref>''Folklore: An Encyclopedia of Beliefs, Customs, Tales, Music, and Art'', Volume 1, edited by Thomas A. Green, [https://books.google.com/books?id=S7Wfhws3dFAC&pg=PA588 p. 588] {{webarchive|url=https://web.archive.org/web/20150519001150/https://books.google.com/books?id=S7Wfhws3dFAC&pg=PA588|date=2015-05-19}}</ref> This phenomenon goes by many names.

==== Albania ====
In [[Albanian folk beliefs]], ''Mokthi'' is believed to be a male spirit with a golden [[Fez (hat)|fez]] hat who appears to women who are usually tired or suffering and stops them from moving. It is believed that if they can take his golden hat, he will grant them a wish, but then he will visit them frequently although he is harmless. There are talismans that can provide protection from Mokthi and one way is to put one's husband's hat near the pillow while sleeping. ''Mokthi'' or ''Makthi'' in [[Albanian language|Albanian]] means "Nightmare".<ref>{{cite book |last=Qazimi |first=Azem |title=Fjalor i Mitologjisë dhe Demonologjisë Shqiptare |publisher=Plejad |year=2008 |isbn=978-99956-706-1-0 |location=Tiranë, Albania |pages=97 |language=sq}}</ref>

==== Arab ====
The names of sleep paralysis vary in some Arab countries; it is popularly known as "Al-Jathoom," in Morocco it is called "Boughtat," and in other regions it is known as "Raboos." This entity, believed to be a jinn, perches on the sleeper's chest.<ref name=":2" /><ref>{{cite web|title=Have you heard of Al-Jathoom? What is its relation to jinn, and how does science explain this phenomenon?|url=https://www.aljazeera.net/health/2021/11/12/%d8%a7%d9%84%d8%ac%d8%a7%d8%ab%d9%88%d9%85-%d8%b4%d9%84%d9%84-%d8%a7%d9%84%d9%86%d9%88%d9%85-2|access-date=2025-09-02|website=Al Jazeera Net|author=Dr. Osama Abu-Rub|language=en}}</ref>

==== Bengal ====
In [[Bangladeshi folk literature|Bengali folklore]], sleep paralysis is believed to be caused by a supernatural entity called ''[[Ghosts in Bengali culture|Boba]]'' ({{langx|bn|বোবা|lit=dumb}}). ''Boba'' attacks a person by strangling him when the person sleeps in a [[supine position]]. In [[Bengal]], the phenomenon is called ''Bobay Dhora'' ({{langx|bn|বোবায় ধরা|lit=Struck by ''Boba''}}).<ref>{{Citation|last=health.banglablog24.com|script-title=bn:রাতের বেলায় ‘বোবা ভূত ধরা’ এর প্রতিকার জানুন!|url=http://health.banglablog24.com/রাতের-বেলায়-বোবা-ভূত-ধরা/}}</ref>

==== Cambodia ====
Sleep paralysis among [[Cambodia]]ns is known as "the ghost pushes you down," and entails the belief in dangerous visitations from deceased relatives.<ref name=":3" />

==== Japan ====
Sleep paralysis among the [[Japan]]ese is known as ''kannashibara''/''kannashibari'' (金縛り), lit. "metal binding" and entails the belief of dangerous visitations from childlike [[Yōkai]], called a ''[[makuragaeshi]]'' (枕返し or 反枕, lit. "pillow flip"), sitting on the victim's chest.

==== Italy ====
In the different regions of [[Italy]], there are many examples of supernatural beings associated with sleep paralysis. In the regions of [[Marche]] and [[Abruzzo]], it is referred to as a ''{{interlanguage link|Pandafeche|it}}'' or ''{{interlanguage link|pantafica|it}}'' attack;<ref name=":1" /> the ''Pandafeche'' usually refers to an evil [[Witchcraft|witch]], sometimes a ghostlike spirit or a terrifying catlike creature, that mounts on the chest of the victim and tries to harm him. The only way to avoid her is to keep a bag of sand or beans close to the bed, so that the witch will stop to count how many beans or sand-grains are inside it. A similar tradition is present in the [[Sardinia]]n folklore, where the ''Ammuntadore'' is known as a creature that mounts on the people's chest during their sleep to give them nightmares, and it can change its shape according to the person's fears. In Northern Italy, specifically in the [[Tyrol]] area, the ''Trud'' is a witch that sits on the people's chest at night, making them unable to breathe; to chase her away, people should make the [[Sign of the cross|sign of the Cross]], something that would need a great struggle in a situation of paralysis.<ref>{{cite book|title=Trentino da leggenda|publisher=Panorama|year=2000|isbn=|location=|pages=125}}</ref> A similar folklore is present in the [[Samnium|Sannio]] area, around the city of [[Benevento]], where the witch is called ''[[Witches of Benevento|Janara]]''.<ref name=":10" /> In Southern Italy, sleep paralysis is usually explained with the presence of a [[Sprite (folklore)|sprite]] standing on the people's chest; if the person manages to catch the sprite (or steal his hat), in exchange for his freedom (or to have his hat back) he can reveal the hiding place of a rich treasure; this sprite has different names in different regions of Italy: Monaciello in [[Campania]], Monachicchio in [[Basilicata]], Laurieddhu or Scazzamurill in [[Apulia]], Mazzmuredd in [[Molise]].<ref name=":10">{{cite book|last=Lazzarato|first=Francesca|title=Le creature del Piccolo Popolo|publisher=Mondadori|year=1995|isbn=88-04-40555-4|location=|pages=23–46}}</ref>

==== Newfoundland ====
In [[Newfoundland and Labrador|Newfoundland]], which is in eastern Canada, sleep paralysis is referred to as the Old Hag,<ref name=":8" /><ref>{{cite book|title=Hag (noun)|publisher=University of Toronto Press|others=W. J. Kirwin and J.D.A Widdowson|year=1990|editor-last=Story|editor-first=George|location=Toronto}}</ref> and victims of a ''hagging'' are said to be ''hag-ridden'' upon awakening.<ref>{{cite journal|last=Hufford|first=David|date=2005|title=Sleep Paralysis as Spiritual Experience|journal=Transcultural Psychiatry|volume=42|issue=1|pages=11–45|doi=10.1177/1363461505050709|pmid=15881267|s2cid=8400951}}</ref> Victims report being completely conscious, but unable to speak or move, and report a person or an animal which sits upon their chest.<ref name=":9">{{cite journal|last=Ness|first=Robert|date=1978|title=The old hag phenomenon as sleep paralysis: A biocultural interpretation|journal=Culture, Medicine and Psychiatry|volume=2|issue=1|pages=15–39|doi=10.1007/BF00052448|pmid=699620|s2cid=1613137}}</ref> Despite the name, the attacker can be either male or female.<ref>{{cite book|last=Hufford|first=David|title=Out of the Ordinary: Folklore and the Supernatural|publisher=University Press of Colorado|year=1995|editor-last=Walker|editor-first=Barbara|pages=11–45|chapter=Beings Without Bodies: An Experience-Centered Theory of the Belief in Spirits}}</ref> Some suggested cures or preventions for the Old Hag include sleeping with a Bible under the pillow,<ref name=":9" /> calling the sleeper's name backwards<ref>{{cite web|last=Rieti|first=Barbara|date=1989|title=The Black Heart in Newfoundland: The Magic of the Book|url=http://collections.mun.ca/cdm/ref/collection/cult_trad/id/3233|access-date=2020-06-25|website=Culture and Tradition Volume 13}}</ref> or in an extreme example, sleeping with a shingle or board embedded with nails strapped to the chest.<ref>{{cite journal|date=1896|title=Superstitions in Newfoundland|journal=The Journal of American Folklore|volume=9|issue=34|pages=222–223|doi=10.2307/533410|jstor=533410}}</ref> This object was called a Hag Board.<ref>{{cite journal|last=Guy|first=Ray|date=2010|title=That Old Nonsense|url=http://collections.mun.ca/cdm/compoundobject/collection/quarterly/id/40813/rec/65|journal=The Newfoundland Quarterly|volume=103|issue=2|pages=12–13}}</ref> The Old Hag is well-enough known in the province to be a pop culture figure, appearing in films and plays<ref>{{cite news|date=19 March 2018|title=Gordon Pinsent explores depression with short film Martin's Hagge|work=CBC.ca|url=https://www.cbc.ca/news/canada/newfoundland-labrador/martins-hagge-gordon-pinsent-1.4582725|access-date=27 June 2020}}</ref> as well as in crafted objects.<ref>{{cite journal|last=Jarvis|first=Dale Gilbert|date=October 2018|title=Exploring Folklore Through Craft with Janet Peter|url=https://www.mun.ca/ich/resources/ICH_Case_Study_001__Janet_Peter_WEB2.pdf|journal=Living Heritage Economy Case Study|volume=001}}</ref>

====Nigeria====
[[Nigeria]]<ref>{{cite journal|last1=Olunu|first1=Esther|last2=Kimo|first2=Ruth|last3=Onigbinde|first3=Esther Olufunmbi|last4=Akpanobong|first4=Mary-Amadeus Uduak|last5=Enang|first5=Inyene Ezekiel|last6=Osanakpo|first6=Mariam|last7=Monday|first7=Ifure Tom|last8=Otohinoyi|first8=David Adeiza|last9=Fakoya|first9=Adegbenro Omotuyi John|date=2018|title=Sleep Paralysis, a Medical Condition with a Diverse Cultural Interpretation|journal=International Journal of Applied and Basic Medical Research|volume=8|issue=3|pages=137–142|doi=10.4103/ijabmr.IJABMR_19_18|issn=2229-516X|pmc=6082011|pmid=30123741 |doi-access=free }}</ref> has myriad interpretations of the cause of sleep paralysis, due to numerous cultures and belief systems that exist there.

==== United States ====
Sleep paralysis is sometimes interpreted as space alien abduction in the [[United States]].<ref>{{cite journal|last1=McNally|first1=Richard J.|last2=Clancy|first2=Susan A.|date=2005-03-01|title=Sleep Paralysis, Sexual Abuse, and Space Alien Abduction|journal=Transcultural Psychiatry|language=en|volume=42|issue=1|pages=113–122|doi=10.1177/1363461505050715|issn=1363-4615|pmid=15881271|s2cid=9569785}}</ref>

=== Literature ===
Various forms of [[magic (paranormal)|magic]] and [[spiritual possession]] were also advanced as causes, in literature. In nineteenth-century [[Europe]], the vagaries of diet were thought to be responsible. For example, in [[Charles Dickens]]'s ''[[A Christmas Carol]]'', [[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) offers the following advice about nightmares:

<blockquote>Great attention is to be paid to regularity and choice of diet. Intemperance of every kind is hurtful, but nothing is more productive of this disease than drinking bad wine. Of eatables those which are most prejudicial are all fat and greasy meats and pastry. Moderate exercise contributes in a superior degree to promote the digestion of food and prevent flatulence; those, however, who are necessarily confined to a sedentary occupation, should particularly avoid applying themselves to study or bodily labor immediately after eating. Going to bed before the usual hour is a frequent cause of night-mare, as it either occasions the patient to sleep too long or to lie long awake in the night. Passing a whole night or part of a night without rest likewise gives birth to the disease, as it occasions the patient, on the succeeding night, to sleep too soundly. Indulging in sleep too late in the morning, is an almost certain method to bring on the paroxysm, and the more frequently it returns, the greater strength it acquires; the propensity to sleep at this time is almost irresistible.<ref>{{cite web|url=http://www.mspong.org/cyclopedia/medicine.html#nightmare|title=The Household Cyclopedia – Medicine<!-- Bot generated title -->|website=mspong.org|url-status=dead|archive-url=https://web.archive.org/web/20091202195226/http://www.mspong.org/cyclopedia/medicine.html#nightmare|archive-date=2009-12-02}}</ref></blockquote>

[[J. M. Barrie]], the author of the [[Peter Pan (character)|Peter Pan]] stories, may have had sleep paralysis. He said of himself "In my early boyhood it was a sheet that tried to choke me in the night."<ref>{{cite book|title=My Ghastly Dream.|last=Barrie|first=James|publisher=Edinburgh Evening Post|year=1887}}</ref> He also described several incidents in the Peter Pan stories that indicate that he was familiar with an awareness of a loss of muscle tone whilst in a dream-like state. For example, Maimie is asleep but calls out "What was that....It is coming nearer! It is feeling your bed with its horns-it is boring for [into] you",<ref>{{cite book|title=Peter Pan in Kensington Gardens|last=Barrie|first=James|publisher=Hodder and Stoughton|year=1906}}</ref> and when the Darling children were dreaming of flying, Barrie says "Nothing horrid was visible in the air, yet their progress had become slow and laboured, exactly as if they were pushing their way through hostile forces. Sometimes they hung in the air until Peter had beaten on it with his fists."<ref>{{cite book|title=Peter and Wendy|last=Barrie|first=James|publisher=Hodder and Stoughton|year=1911}}</ref> Barrie describes many [[parasomnia]]s and neurological symptoms in his books and uses them to explore the nature of consciousness from an experiential point of view.<ref>{{cite book|title=Peter Pan and the Mind of J. M. Barrie. An Exploration of Cognition and Consciousness.|last=Ridley|first=Rosalind|publisher=Cambridge Scholars Publishing|year=2016|isbn=978-1-4438-9107-3}}</ref>

[[Herman Melville]] described an episode resembling sleep paralysis in his novel ''[[Moby-Dick]]'' (1851). In Chapter 4 ("The Counterpane"), Ishmael recalls a childhood incident in which "a supernatural hand seemed placed in mine," leaving him aware but unable to move. The passage has been analyzed as one of the earliest fictional depictions consistent with modern clinical descriptions of the condition.<ref>{{cite journal |last=Herman |first=J. |title=Literature and sleep: An instance of sleep paralysis in Moby Dick |journal=Sleep |year=1997 |volume=20 |issue=7 |pages=577–579 |doi=10.1093/sleep/20.7.577 |pmid=9322274}}</ref>

=== Documentary films ===
[[The Nightmare (2015 American film)|''The Nightmare'']] is a 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 phenomena as [[alien abduction]], the [[near-death experience]] and [[shadow person|shadow people]] can, in many cases, be attributed to sleep paralysis. The "real-life" horror film debuted at the [[2015 Sundance Film Festival|Sundance Film Festival]] on January 26, 2015, and premiered in theatres on June 5, 2015.<ref>{{cite web|url=http://www.firstshowing.net/2015/watch-first-trailer-for-creepy-sleep-paralysis-doc-the-nightmare/|title=Watch: First Trailer for Creepy Sleep Paralysis Doc 'The Nightmare'|website=firstshowing.net|date=May 2015 |url-status=live|archive-url=https://web.archive.org/web/20150503024546/http://www.firstshowing.net/2015/watch-first-trailer-for-creepy-sleep-paralysis-doc-the-nightmare/|archive-date=2015-05-03}}</ref>

== See also ==
* {{annotated link|Catatonia}}

== References ==
{{Reflist}}

== External links ==
* [http://www.stanford.edu/~dement/paralysis.html Sleep information and links] {{Webarchive|url=https://web.archive.org/web/20160306075040/http://stanford.edu/~dement/paralysis.html |date=2016-03-06 }} from Stanford University
* [https://web.archive.org/web/20030605094412/http://www.arts.uwaterloo.ca/~acheyne/S_P.html Sleep Paralysis and Associated Hypnagogic and Hypnopompic Experiences] from University of Waterloo

{{Medical condition classification and resources| DiseasesDB      =12182
| ICD10           = {{ICD10|G47.8}}, {{ICD10|G83.8}}
| ICD9            = <!-- {{ICD9|xxx}} -->
| ICDO            =
| OMIM            =
| MedlinePlus     =
| MeSH            = D020188
| GeneReviewsNBK  =
| GeneReviewsName =
| SNOMED CT       = 277180005
|ICD11={{ICD11|7B01.1}}}}
{{SleepSeries2|collapsed}}
{{Authority control}}

[[Category:Dream]]
[[Category:Hallucinations]]
[[Category:Neuropsychology]]
[[Category:Parasomnias]]
[[Category:Sleep disorders]]
[[Category:Sleep in mythology and folklore]]
[[Category:Sleep physiology]]
[[Category:Symptoms and signs of mental disorders]]

[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Wikipedia neurology articles ready to translate]]