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a sleep disorder characterized by excessive daytime sleepiness and recurring unwanted episodes of sleep ("sleep attacks"). People with narcolepsy may abruptly fall asleep at almost any time, including while talking, eating, or even walking. The attacks may range from embarrassing or inconvenient to severely disabling, interfering with a person's daily life. An estimated 125,000–250,000 people in the United States have narcolepsy; it occurs about equally in males and females.

Most people with narcolepsy also experience cataplexy, sudden muscular weakness without loss of consciousness, which usually accompanies laughter or anger. Other symptoms, occurring just after falling asleep or upon awakening, include sleep paralysis (a feeling that one cannot move) and vivid hallucinations.

The cause of narcolepsy is not known with certainty, but most people with narcolepsy have low levels of orexin (or hypocretin), a neurotransmitter that promotes wakefulness. In the case of people with narcolepsy and cataplexy, the cause appears to be an autoimmune response that attacks the brain's orexin-producing neurons. There is no cure. Treatment, including regular planned naps and the use of stimulant drugs (e.g., amphetaminesamphetamine
, any one of a group of drugs that are powerful central nervous system stimulants. Amphetamines have stimulating effects opposite to the effects of depressants such as alcohol, narcotics, and barbiturates.
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) plus antidepressantsantidepressant,
any of a wide range of drugs used to treat psychic depression. They are given to elevate mood, counter suicidal thoughts, and increase the effectiveness of psychotherapy.
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 for cataplexy, can help to control its symptoms.

The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a disease the main symptom of which is an uncontrollable desire for sleep. Narcolepsy can develop after infections (epidemic encephalitis and malaria, for example) or head injuries; it may also be caused by certain brain tumors. Sometimes no apparent cause can be discovered, as in congenital, or genuine, narcolepsy. In addition to being characterized by an uncontrollable desire for sleep, narcolepsy is characterized by cataplectic attacks (loss of muscle tone brought about by exaggerated emotion) and by sudden arousals from nocturnal sleep with a loss of muscle tone. The duration of narcoleptic attacks is brief—from one to 30 minutes. The course of narcolepsy is chronic, but the intensity diminishes with age. Treatment involves both the elimination of the underlying cause and the use of pharmacotherapeutic techniques.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A disorder of sleep mechanism characterized by two or more of four distinct symptoms: uncontrollable periods of daytime drowsiness, cataleptic attacks of muscular weakness, sleep paralysis, and vivid nocturnal or hypnogogic hallucinations.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Among their research experiments include those that seek to "restore orexin signaling in the brains of narcoleptic mice and the new discovery of more histamine neurons in people with narcolepsy,'' according to Dr.
For the study, researchers examined five narcoleptic brains and seven control brains from human cadavers.
The sleep of narcoleptics is abnormal and characterized by: a short sleep latency; frequent sleep onset REM periods (i.e., REM sleep begins within 30 minutes of going to sleep); REM period interrupted by arousals; higher than normal amount of time spent in stage 1 but less than normal amount Spent in slow wave sleep; and frequent arousals from sleep.
Narcoleptics often report that taking a nap or succumbing to these sleep attacks help them, as they often feel refreshed upon waking, although usually only for a short period.
Diagnosed at the age of five, she became the youngest known narcoleptic in the UK and has spent the past 14 years learning how to live a normal life.
Scientists have discovered that all of us, except narcoleptics, have a chemical called orexin in our brain to keep us awake.
At Stanford and the University of California-Los Angeles, scientists studied preserved brains from narcoleptics and found that all were missing HC-secreting cells in the hypothalamus.
The scientists, however, had other evidence that hypocretins are the key to the disorder: The neurotransmitters were missing in the cerebrospinal fluid of most of the narcoleptics they studied.
These perception levels were then compared between medicated and non-medicated narcoleptics.
Whereas those with sleep apnea syndrome often wake up in the middle of the night because they cannot breathe, narcoleptics are not known for breathing disturbances.
Laboratory tests have shown that narcoleptics do not pass through the lighter stages of sleep.
Excessive daytime sleepiness is universal among narcoleptics, but other symptoms are more variable, he noted.