Sleep paralysis is a condition that may occur in normal subjects or be associated with
narcolepsyNarcolepsy is chronic sleep disorder, or dyssomnia. The condition is characterized by excessive daytime sleepiness in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school...
,
cataplexyCataplexy is sudden and transient episode of loss of muscle tone, often triggered by emotions. It is a rare disease , but frequently affects people who have narcolepsy, a disorder whose principal signs are EDS , sleep attacks, sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep...
, and hypnagogic hallucinations. The
pathophysiologyPathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
of this condition is closely related to the normal hypotonia that occur during REM sleep. When considered to be a disease, isolated sleep paralysis is classified as
MeSHMedical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching...
D020188. Some evidence suggests that it can also, in some cases, be a symptom of
migraineMigraine is a neurological syndrome characterized by altered bodily perceptions, severe headaches, and nausea. Physiologically, the migraine headache is a neurological condition more common to women than to men. The word migraine was borrowed from Old French migraigne...
.
Physiologically, sleep paralysis is closely related to the paralysis that occurs as a natural part of REM (rapid eye movement) sleep, which is known as REM atonia.
Sleep paralysis is a condition that may occur in normal subjects or be associated with
narcolepsyNarcolepsy is chronic sleep disorder, or dyssomnia. The condition is characterized by excessive daytime sleepiness in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school...
,
cataplexyCataplexy is sudden and transient episode of loss of muscle tone, often triggered by emotions. It is a rare disease , but frequently affects people who have narcolepsy, a disorder whose principal signs are EDS , sleep attacks, sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep...
, and hypnagogic hallucinations. The
pathophysiologyPathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
of this condition is closely related to the normal hypotonia that occur during REM sleep. When considered to be a disease, isolated sleep paralysis is classified as
MeSHMedical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching...
D020188. Some evidence suggests that it can also, in some cases, be a symptom of
migraineMigraine is a neurological syndrome characterized by altered bodily perceptions, severe headaches, and nausea. Physiologically, the migraine headache is a neurological condition more common to women than to men. The word migraine was borrowed from Old French migraigne...
.
Symptoms and characteristics
Physiologically, sleep paralysis is closely related to the paralysis that occurs as a natural part of REM (rapid eye movement) sleep, which is known as REM atonia. Sleep paralysis occurs when the
brainThe brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all...
awakes from a REM state, but the body paralysis persists. This leaves the person fully conscious, but unable to move. The paralysis can last from several seconds to several minutes "after which the individual may experience panic symptoms and the realization that the distorted perceptions were false". As the correlation with REM sleep suggests, the paralysis is not entirely complete; use of EOG traces shows that eye movement can be instigated during such episodes. When there is an absence of narcolepsy, sleep paralysis is referred to as isolated sleep paralysis (ISP). "ISP appears to be far more common and recurrent among people of African descent than among whites or Nigerian Africans", and is often referred to within African communities as "the Devil on your back."
In addition, the paralysis state may be accompanied by terrifying hallucinations (
hypnopompicA hypnopompic state is the state of consciousness leading out of sleep, a term coined by the spiritualist Frederick Myers. Its twin is the hypnagogic state at sleep onset; though often conflated, the two states are not identical...
or
hypnagogicHypnagogia , often misspelled hypnogaia or hypnogogia, is a term coined by Alfred Maury for the transitional state between wakefulness and sleep.-Definitions and synonyms:Sometimes the word...
) and an acute sense of danger. Sleep paralysis is particularly frightening to the individual because of the vividness of such hallucinations. The hallucinatory element to sleep paralysis makes it even more likely that someone will interpret the experience as a dream, since completely fanciful, or dream-like, objects may appear in the room alongside one's normal vision. Some scientists have proposed this condition as an explanation for alien abductions and
ghostA ghost has been defined as the disembodied spirit or soul of a deceased person, although in popular usage the term refers only to the apparition of such a person...
ly encounters. A study by
Susan BlackmoreSusan Jane Blackmore is an English freelance writer, lecturer, and broadcaster on psychology and the paranormal, perhaps best known for her book The Meme Machine.-Career:...
and Marcus Cox (the Blackmore-Cox study) of the
University of the West of EnglandThe University of the West of England is a university based in the English city of Bristol. Its main campus is at Frenchay, about five miles north of the city centre...
supports the suggestion that reports of alien abductions are related to sleep paralysis rather than to
temporal lobeThe temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemispheres of the brain....
lability.
Possible causes
Sleep paralysis occurs during REM sleep, thus preventing the body from manifesting movements made in the subject's dreams. Very little is known about the physiology of sleep paralysis. However, some have suggested that it may be linked to post-synaptic inhibition of
motor neuronIn vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...
s in the
ponsThe pons is a structure located on the brain stem. It is cranial to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum...
region of the
brainThe brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all...
. In particular, low levels of
melatoninMelatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring hormone found in animals and in some other living organisms, including algae. Circulating levels vary in a daily cycle, and melatonin is important in the regulation of the circadian rhythms of several...
may stop the
depolarizationIn biology, depolarization is a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential...
current in the nerves, preventing the stimulation of the muscles and any consequent enactment of the dream activity by the body (e.g. preventing a sleeper from flailing his legs when dreaming about running).
Several studies have concluded that many or most people will experience sleep paralysis at least once or twice in their lives.
A study conducted by Sedaghat F. et al. has investigated the prevalence of sleep paralysis among Iranian medical students. 24.1% of students reported experiencing sleep paralysis at least once in their lifetime. The same result was reported among Japanese, Nigerian, Kuwaiti, Sudanese and American students.
Many people who commonly enter sleep paralysis also suffer from
narcolepsyNarcolepsy is chronic sleep disorder, or dyssomnia. The condition is characterized by excessive daytime sleepiness in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school...
. In non-Nigerian Africans,
panic disorderPanic disorder is an anxiety disorder characterized by recurring severe panic attacks. It may also include significant behavioral change lasting at least a month and of ongoing worry about the implications or concern about having other attacks. The latter are called anticipatory attacks...
occurs with sleep paralysis more frequently than in Caucasians.
Some reports read that various factors increase the likelihood of both paralysis and hallucinations. These include:
- Sleeping in a face upwards or supine position
The supine position is a position of the body; lying down with the face up, as opposed to the prone position, which is face down, sometimes with the hands behind the head or neck...
- Irregular sleeping schedules; naps, sleeping in, sleep deprivation
Sleep deprivation, a sleep disorder characterized by having too little sleep, can be either chronic or acute. Long-term sleep deprivation causes death in lab animals...
- Increased stress
- Sudden environmental/lifestyle changes
- A lucid dream that immediately precedes the episode.
Treatment
Treatment starts with patient education about sleep stages and about the muscle atonia that is typically associated with REM sleep. For most healthy individuals, avoiding chronic sleep deprivation is enough to relieve symptoms. It is recommended that patients be evaluated for
narcolepsyNarcolepsy is chronic sleep disorder, or dyssomnia. The condition is characterized by excessive daytime sleepiness in which a person experiences extreme fatigue and possibly falls asleep at inappropriate times, such as while at work or at school...
if symptoms persist.
Related phenomena
Many perceptions associated with sleep paralysis (visceral buzzing, loud sounds, adrenal mental state, presences, and the paralysis itself) also constitute a common phase in the early progression of episodes referred to as out of body experiences. Mental focus varies between the two conditions; paralysis sufferers tend to fixate on reestablishing operation of the body, whereas subjects of out-of-body episodes are more occupied by perceived non-equivalence with the body.
Folklore
Complete references to many cultures are given in the References section
- In African culture, isolated sleep paralysis is commonly referred to as "the witch riding your back".
- In Cambodian, Laotian, and Thai culture, sleep paralysis is called pee umm and khmout sukkhot. It is described as an event in which the person is sleeping and dreams that one or more ghostly figures are nearby or even holding him or her down. The sufferer usually thinks that he or she is awake but unable to move or make any noises. This is not to be confused with pee khao and khmout jool, ghost possession.
- In Hmong
The terms Mong and Hmong refer to an Asian ethnic group in the mountainous regions of southeast Asia. Hmong are also one of the largest sub-groups in the Miao minzu population in southern China. Hmong groups began a gradual southward migration in the 18th century due to political unrest and to...
culture, sleep paralysis describes an experience called "dab tsog" or "crushing demon." Often the sufferer claims to be able to see a tiny figure, no larger than a child, sitting on his or her chest. What is alarming is that a vast number of American Hmong have died in their sleep, prompting the Centers for Disease Control to create the term "Sudden Unexpected Nocturnal Death Syndrome" (see Sudden unexplained death syndromeSudden unexpected death syndrome or Sudden unexpected nocturnal death syndrome is sudden unexpected death of adolescents and adults during sleep....
) or "SUNDS" for short; this is now theorized to be a form of Brugada syndromeThe Brugada syndrome is a genetic disease that is characterised by abnormal electrocardiogram findings and an increased risk of sudden cardiac death...
.
- In Vietnamese culture, sleep paralysis is referred to as "ma đè", meaning "held down by a ghost" or "bóng đè", meaning "held down by a shadow". Many people in this culture believe that a ghost has entered one's body, causing the paralyzed state.
- In Chinese culture, sleep paralysis is widely known as "鬼壓身/鬼压身" (pinyin
Pinyin , or more formally Hanyu Pinyin , is currently the most commonly used romanization system for Standard Mandarin. Hanyu means the Chinese language, and pinyin means "phonetics", or more literally, "spelling sound" or "spelled sound"...
: guǐ yā shēn) or "鬼壓床/鬼压床" (pinyinPinyin , or more formally Hanyu Pinyin , is currently the most commonly used romanization system for Standard Mandarin. Hanyu means the Chinese language, and pinyin means "phonetics", or more literally, "spelling sound" or "spelled sound"...
: guǐ yā chuáng), which literally translate into "ghost pressing on body" or "ghost pressing on bed." A more modern term is "夢魘/梦魇" (pinyinPinyin , or more formally Hanyu Pinyin , is currently the most commonly used romanization system for Standard Mandarin. Hanyu means the Chinese language, and pinyin means "phonetics", or more literally, "spelling sound" or "spelled sound"...
: mèng yǎn).
- In Japanese
is a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family. There are a number of proposed relationships with other languages, but none have gained general acceptance...
culture, sleep paralysis is referred to as kanashibari (金縛り, literally "bound or fastened in metal," from kane "metal" and shibaru" to bind, to tie, to fasten"). This term is occasionally used by English speaking authors to refer to the phenomenon both in academic papers and in pop psychThe term popular psychology refers to concepts and theories about human mental life and behaviour that are purportedly based on psychology and that attain popularity among the general population...
literature.
- In Philippine culture
Culture of the Philippines reflects the complexity of the history of the Philippines through the blending of several diverse indigenous cultures, and foreign cultures such as Chinese and Spanish....
, "bangungut", or sudden unexplained death syndromeSudden unexpected death syndrome or Sudden unexpected nocturnal death syndrome is sudden unexpected death of adolescents and adults during sleep....
, has traditionally been attributed to nightmares. People who have claimed to survive such nightmares have reported experiencing the symptoms of sleep paralysis.
- In Hungarian
Hungary , in English officially the Republic of Hungary , is a landlocked country in the Carpathian Basin of Central Europe, bordered by Austria, Slovakia, Ukraine, Romania, Serbia, Croatia, and Slovenia. Its capital is Budapest. Hungary is a member of OECD, NATO, EU, V4 and is a Schengen state...
folk culture sleep paralysis is called "lidércnyomás" ("lidérc pressing") and can be attributed to a number of supernatural entities like "lidérc" (wraith), "boszorkány" (witch), "tündér" (fairy) or "ördögszerető" (demon lover). The word "boszorkány" itself stems from the Turkish root "bas-", meaning "to press".
- In Iceland
The Republic of Iceland is a European island country located in the North Atlantic Ocean. It has a population of about 320,000 and a total area of 103,000 km². Its capital and largest city is Reykjavík, whose surrounding area is home to approximately two thirds of the national population...
folk culture sleep paralysis is generally called having a "MaraA mare or nightmare is a spirit or goblin in Germanic folklore which rides on people's chests while they sleep, bringing on bad dreams . The mare is attested as early as in the Norse Ynglinga saga from the 13th century, but the belief itself is likely to be considerably older...
". A goblin or a succubus (since it is generally female) believed to cause nightmares (the origin of the word 'Nightmare' itself is derived from her name). Other European cultures share variants of the same folklore, calling her under different names; Proto-Germanic: marōn; Old English: mære; German: Mahr; Dutch: nachtmerrie; Icelandic, Old Norse, Faroese, and Swedish: mara; Danish: mare; Norwegian: mare; Old Irish: morrigain; Slovene: môra; Bulgarian, Serbian, Polish: mora; French: cauchemar; Romanian: moroi; Czech: můra. The origin of the belief itself is much older and goes back to the reconstructed Proto Indo-European root mora-, an incubus, from the root mer- "to rub away" or "to harm".
- In Malta
Malta , officially the Republic of Malta , is a densely populated developed European country in the European Union. The Southern European island nation is an archipelago that includes the inhabited islands of Malta, Gozo and Comino, along with a number of smaller, uninhabited islands...
, folk culture attributes a sleep paralysis incident to an attack by the "Haddiela" who is the wife of the "Hares", the entity in Maltese folk culture which haunts the individual in similar ways as to those of a poltergeist. As believed in folk culture, to rid oneself of the Haddiela, one must place a piece of silverware or a knife under the pillow prior to sleep.
- In New Guinea, people refer to this phenomenon as "Suk Ninmyo", believed to originate from sacred trees that use human essence to sustain its life. The trees are said to feed on human essence during night as to not disturb the human's daily life, but sometimes people wake unnaturally during the feeding, resulting in the paralysis.
- In Turkish
Turkey , known officially as the Republic of Turkey
, is a Eurasian country that stretches across the Anatolian peninsula in Western Asia and Thrace in the Balkan region of southeastern Europe...
culture, sleep paralysis is often referred to as "karabasan" ("The dark presser/assailer"). It is believed to be a creature which attacks people in their sleep, pressing on their chest and stealing their breath.
- In Mexico, it's believed that sleep paralysis is in fact the spirit of a dead person getting on the person and impeding movement, calling this "se me subió el muerto" (the dead person got on me).
- In many parts of the Southern United States, the phenomenon is known as a "hag
A hag is a wizened old woman, or a kind of fairy or goddess having the appearance of such a woman, often found in folklore and children's tales such as Hansel and Gretel. Hags are often seen as malevolent, but may also be one of the chosen forms of shapeshifting deities, such as the Morrígan or...
", and the event is said to often be a sign of an approaching tragedy or accident.
- Ogun Oru is a traditional explanation for nocturnal disturbances among the Yoruba of Southwest Nigeria; ogun oru (nocturnal warfare) involves an acute night-time disturbance that is culturally attributed to demonic infiltration of the body and psyche during dreaming. Ogun oru is characterized by its occurrence, a female preponderance, the perception of an underlying feud between the sufferer's earthly spouse and a 'spiritual' spouse, and the event of bewitchment through eating while dreaming. The condition is believed to be treatable through Christian prayers or elaborate traditional rituals designed to exorcise the imbibed demonic elements.
- In Greece
Greece , officially the Hellenic Republic , is a country in southeastern Europe, situated on the southern end of the Balkan Peninsula....
and CyprusCyprus , officially the Republic of Cyprus , is a Eurasian island country situated in the eastern Mediterranean, south of Turkey and west of Syria and Lebanon....
, it is believed that sleep paralysis occurs when a ghost-like creature or Demon named Mora, Vrahnas or Varypnas (Greek: Μόρα, Βραχνάς, Βαρυπνάς) tries to steal the victim's speech or sits on the victim's chest causing asphyxiation.
- In Zimbabwean Shona culture the word Madzikirira is used to refer something really pressing one down. This mostly refers to the spiritual world in which some spirit—especially an evil one—tries to use its victim for some evil purpose. The people believe that witches can only be people of close relations to be effective, and hence a witches often try to use one's spirit to bewitch one's relatives.
- In Ethiopian culture the word Dukak is used. Dukak is believed to be some form of evil spirit that possesses people during their sleep. This experience is also believed to be related to use of Khat
Khat , also known as qat, qaat, quat, gat, jaad, chat, chad, chaad and miraa, is a flowering plant native to tropical East Africa and the Arabian Peninsula.Khat contains the alkaloid called cathinone, an amphetamine-like stimulant which is said to cause...
. Most Khat users experience sleep paralysis when quitting after a long time of use.
- Several studies have shown that African-Americans may be predisposed to isolated sleep paralysis also known as "the witch is riding you" or "the haint is riding you". In addition, other studies have shown that African-Americans who have frequent episodes of isolated sleep paralysis, i.e., reporting having one or more sleep paralysis episodes per month coined as "sleep paralysis disorder," were predisposed to having panic attacks. This finding has been replicated by other independent researchers.
- In the Muslim
:A Muslim , , is an adherent of the religion of Islam. The feminine form is Muslimah . Literally, the word means "one who submits ". Muslim is the participle of the same verb of which Islam is the infinitive. Muslims believe that there is only one God, translated in Arabic as Allah...
culture of South AsiaSouth Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries on the west and the east...
(PakistaniThe society of Pakistan comprises numerous diverse cultures and ethnic groups from the Punjabis and Sindhis in the east to the tribal cultures of the Baloch and Pashtun in the west and the ancient Dardic in the north...
, BangladeshiBangladesh has a history. The land, the rivers and the lives of the common people formed a rich heritage with marked differences from neighbouring regions. It has evolved over the centuries and encompasses the cultural diversity of several social groups of Bangladesh.Bangladesh is also a needy...
, Indian MuslimsIslam is India's second-most practiced religion after Hinduism, with more than 13.4% of the country's population identifying themselves as Muslims....
), sleep paralysis is considered an encounter with evil jinnIn Islam, a Djinn is a supernatural creature which occupies a parallel world to that of mankind, and together with humans and angels makes up the three sentient creations of Allah...
s and demonIn religion, folklore, and mythology a demon is a supernatural being that is generally described as a malevolent spirit. In Christian terms demons are generally understood as fallen angels, formerly of God. A demon is frequently depicted as a force that may be conjured and insecurely controlled...
s. It is also assumed that it is caused by the black magicBlack magic or dark magic is a form of sorcery that draws on assumed malevolent powers. This type of magic would be invoked to kill, to steal, to injure, to cause misfortune or destruction, or for personal gain without regard to harmful consequences to others. As a term, "black magic" is normally...
performed by enemies and jealous persons. Spells and CurseA curse is any expressed wish that some form of adversity or unhappiness will befall another person or persons. In particular, a wish that harm or hurt will be inflicted by any supernatural power, such as a spell, a prayer, an imprecation, an execration, magic, witchcraft, a god, a natural force,...
s could also result in a ghoulA ghoul is a mythological monster from ancient Arabian folklore that dwells in burial grounds and other uninhabited places. The English word comes from the Arabic name for the creature: الغول al-ghūl, which literally means "demon"...
haunting a person. Some homes and locations are also alleged to be haunted by these satanSatan is an embodiment of antagonism that originates from the Abrahamic religions, being traditionally considered an angel in Judeo-Christian belief, and a Jinn in Islamic belief...
ic beings.
- In Tamil
Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai . Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by Puducherry , Kerala, Karnataka and Andhra Pradesh...
and Sri LankanThe culture of Sri Lanka has been influenced by many things in the past. Mostly it has been influenced by religion and colonialization by the Dutch, the Portuguese and the British.-New Year:Main article Sinhala and Tamil New Year...
Culture, this particular phenomenon is referred to as 'Amuku Be" or 'Amuku Pei' meaning "the ghost that forces one down".
- In Malay of Malay Peninsula, sleep paralysis is known as 'kena tindih' (or 'ketindihan' in Indonesia), which means "being pressed". Incidents are commonly considered to be the work of a malign agency; occurring in what are explained as blind spots in the field of vision, they are reported as demonic figures.
- In Newfoundland and Labrador
Newfoundland and Labrador is a province of Canada on the country's Atlantic coast in northeastern North America. This easternmost Canadian province comprises two main parts: the island of Newfoundland off the country's eastern coast, and Labrador on the mainland to the northwest of the island.A...
, it is known as the 'Old Hag'. In island folklore, the Hag can be summoned to attack a third party, like a curse. In his 1982 book, The Terror that Comes in the Night, David J. Hufford writes that in local culture the way to call the Hag is to recite the Lord's Prayer backwards. It is also common for believers to claim that those who are not wakened from this paralysis will die.
- In Persian
The Persian people are the majority ethnic group in Iran. However, there are sub-groups who speak the Persian language as their mother tongue throughout the Iranian plateau. The term Persian has also a supra-ethnic significance and has been historically referred to a part of Iranian peoples...
culture it is known as 'bakhtak' (PersianPersian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is widely spoken in Iran, Afghanistan, Tajikistan, Uzbekistan and to some extent in Iraq and Bahrain, and has a status of official language in the first three countries under different names...
: بختک) which is a ghost-like creature who does this.
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