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Sleep paralysis
John Henry Fuseli - The Nightmare.JPG
The Nightmare by Henry Fuseli (1781) is thought to be a depiction of sleep paralysis perceived as a demonic visitation.

SpecialtyPsychiatry, Sleep medicine
SymptomsAwareness but inability to move during waking or falling asleep
DurationLess than a couple of minutes
Risk factorsNarcolepsy, obstructive sleep apnea, alcohol use, sleep deprivation
Diagnostic methodBased on description
Differential diagnosisNarcolepsy, atonic seizure, hypokalemic periodic paralysis, night terror
TreatmentReassurance, sleep hygiene, cognitive behavioral therapy, antidepressants
Frequency8–50%

Sleep paralysis is a state, during waking up or falling asleep, in which a person is aware but unable to move or speak. During an episode, one may hallucinate (hear, feel, or see things that are not there), which often results in fear. Episodes generally last less than a couple of minutes. It may occur as a single episode or be recurrent.

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 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. Sleep paralysis is commonly experienced by lucid dreamers; some lucid dreamers use this as a method of having a lucid dream. Diagnosis is based on a person's description. Other conditions that can present similarly include narcolepsy, atonic seizure, and hypokalemic periodic paralysis.

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.

Between 8% and 50% of people experience sleep paralysis at some point in their life. About 5% of people have regular episodes. Males and females are affected equally. 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.

Signs and symptoms