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Narcolepsy is a disorder marked by excessive daytime sleepiness, uncontrollable sleep attacks, and cataplexy (a sudden loss of muscle tone, usually lasting up to half an hour).


Narcolepsy is the second-leading cause of excessive daytime sleepiness (after obstructive sleep apnea). Persistent sleepiness and sleep attacks are the hallmarks of this condition. The sleepiness has been compared to the feeling of trying to stay awake after not sleeping for two or three days.
People with narcolepsy fall asleep suddenly—anywhere, at any time, maybe even in the middle of a conversation. These sleep attacks can last from a few seconds to more than an hour. Depending on where they occur, they may be mildly inconvenient or even dangerous to the individual. Some people continue to function outwardly during the sleep episodes, such as talking or putting things away. But when they wake up, they have no memory of the event.
Narcolepsy is related to the deep, dreaming part of sleep known as rapid eye movement (REM) sleep. Normally when people fall asleep, they experience 90 minutes of non-REM sleep, which is then followed by REM sleep. People with narcolepsy, however, enter REM sleep immediately. In addition, REM sleep occurs inappropriately throughout the day.
There has been debate over the incidence of narcolepsy. It is thought to affect between one in every 1,000 to 2,000 Americans. The known prevalence in other countries varies, from one in 600 in Japan to one in 500,000 in Israel. Reasons for these differences are not clear.

Causes and symptoms

In 1999 researchers identified the gene that causes narcolepsy. The gene allows cells in the hypothalamus (the part of the brain that regulates sleep behavior) to receive messages from other cells. When this gene is abnormal, cells cannot communicate properly, and abnormal sleeping patterns develop.
The disorder sometimes runs in families, but most people with narcolepsy have no relatives with the disorder. Researchers believe that the inheritance of narcolepsy is similar to that of heart disease. In heart disease, several genes play a role in being susceptible to the disorder, but it usually does not develop without an environmental trigger of some sort.
While the symptoms of narcolepsy usually appear during the teens or 20s, the disease may not be diagnosed for many years. Most often, the first symptom is an overwhelming feeling of fatigue. After several months or years, cataplexy and other symptoms appear.
Cataplexy is the most dramatic symptom of narcolepsy. It affects 75% of people with the disorder. During attacks, the knees buckle and the neck muscles go slack. In extreme cases, the person may become paralyzed and fall to the floor. This loss of muscle tone is temporary, lasting from a few seconds to half an hour, but frightening. The attacks can occur at any time but are often triggered by strong emotions, such as anger, joy, or surprise.
Other symptoms of narcolepsy include:
  • sleep attacks: short, uncontrollable sleep episodes throughout the day
  • sleep paralysis: a frightening inability to move shortly after awakening or dozing off
  • auditory or visual hallucinations: intense, sometimes terrifying experiences at the beginning or end of a sleep period
  • disturbed nighttime sleep: tossing and turning, nightmares, and frequent awakenings during the night


If a person experiences both excessive daytime sleepiness and cataplexy, a diagnosis may be made on the patient history alone. Laboratory tests, however, can confirm a diagnosis. These may include an overnight polysomnogram—a test in which sleep is monitored with electrocardiography, video, and respiratory parameters. A Multiple Sleep Latency Test, which measures sleep latency (onset) and how quickly REM sleep occurs, may be used. People who have narcolepsy usually fall asleep in less than five minutes.
If a diagnosis is in question, a genetic blood test can reveal the existence of certain substances in people who have a tendency to develop narcolepsy. Positive test results suggest, but do not prove, the existence of narcolepsy.
Narcolepsy is a complex disorder, and it is often misdiagnosed. It takes 14 years, on average, for an individual to be correctly diagnosed.


There is no cure for narcolepsy. It is not progressive, and it is not fatal, but it is chronic. The symptoms can be managed with medication or lifestyle adjustment. Amphetamine-like stimulant drugs are often prescribed to control drowsiness and sleep attacks. A drug called sodium oxybate (Xyrem) was tested for use in 2004 and was shown to reduce daytime sleepiness as well as cataplexy attacks when used along with stimulants. Patients who do not like taking high doses of stimulants may choose to take smaller doses and "manage" their lifestyles, such as by napping every few hours to relieve daytime sleepiness. Antidepressants are often effective in treating symptoms of abnormal REM sleep.
With the recent discovery of the gene that causes narcolepsy, researchers are hopeful that therapies can be designed to relieve the symptoms of the disorder.


Narcolepsy is not a degenerative disease, and patients do not develop other neurologic symptoms. However, narcolepsy can interfere with a person's ability to work, play, drive, and perform other daily activities. In severe cases, the disorder prevents people from living a normal life, leading to depression and a loss of independence.

Key terms

Cataplexy — A symptom of narcolepsy in which there is a sudden episode of muscle weakness triggered by emotions. The muscle weakness may cause the person's knees to buckle, or the head to drop. In severe cases, the patient may become paralyzed for a few seconds to minutes.
Hypnagogic hallucinations — Dream-like auditory or visual hallucinations that occur while falling asleep.
Hypothalamus — A part of the forebrain that controls heartbeat, body temperature, thirst, hunger, body temperature and pressure, blood sugar levels, and other functions.
Sleep paralysis — An abnormal episode of sleep in which the patient cannot move for a few minutes, usually occurring on falling asleep or waking up. Often found in patients with narcolepsy.



Siegel, Jeremy M. "Narcolepsy." Scientific American January 2000.〈〉.
"Xyrem Study for EDS in Narcolepsy Shows Positive Data Across All Measures." Pain & Central Nervous System Week January 14, 2004: 69.


American Sleep Disorders Association. 1610 14th St. NW, Suite 300, Rochester, MN 55901. (507) 287-6006.
Narcolepsy Network. PO Box 42460, Cincinnati, OH 45242. (973) 276-0115.
National Center on Sleep Disorders Research. Two Rockledge Centre, 6701 Rockledge Dr., Bethesda, MD 20892. (301) 435-0199.
National Sleep Foundation. 1522 K St., NW, Suite 500, Washington, DC 20005. (202) 785-2300.
Stanford Center for Narcolepsy. 1201 Welch Rd-Rm P-112, Stanford, CA 94305. (415) 725-6517.
University of Illinois Center for Narcolepsy Research. 845 S. Damen Ave., Chicago, IL 60612. (312) 996-5176.


"Stanford Researchers Nab Narcolepsy Gene For SleepDisorders." Stanford University Medical Center. [cited August 5, 1999].
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


recurrent, uncontrollable, brief episodes of sleep, often associated with hallucinations just beforehand or just afterward, or cataplexy or sleep paralysis. adj., adj narcolep´tic.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(nar'kō-lep-sē), [MIM*161400]
A sleep disorder that usually appears in young adulthood, consisting of recurring episodes of sleep during the day and often disrupted nocturnal sleep; frequently accompanied by cataplexy, sleep paralysis, and hypnagogic hallucinations; a genetically determined disease.
[narco- + G. lēpsis, seizure]
Farlex Partner Medical Dictionary © Farlex 2012


n. pl. narcolep·sies
A disorder characterized by sudden and uncontrollable, though often brief, attacks of deep sleep, sometimes accompanied by paralysis and hallucinations.

nar′co·lep′tic (-lĕp′tĭk) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Sleeping sickness Sleep disorders A condition characterized by uncontrollable, recurrent, brief episodes of sleep associated with excess daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, and often disturbed REM sleep; narcolepsy affects 125,000 US–prevalence 40/105; it is defined as a daytime mean sleep latency of < 5 mins, with verification of REM in 2 of 5 daytime nap periods; narcoleptics may have amnesia for the 'absences,' have fallen asleep while driving or while at work and prefer shift work as 'drowsiness' is more socially acceptable; it may also be accompanied by sleep paralysis Prevalence 1:600–Japan, 1:2400–US, 1:500, 000–Israel, ♂:♀ ratio 1:1, onset age 15– 35; 98-100% of narcoleptics have HLA-DR2 and/or HLA-DQw1 Clinical Narcolepsy tetrad; if accompanied by cataplexy, Pt feels a sense of absolute urgency for sleep in often inappropriate situations–while standing, eating, carrying on conversations, accompanied by blurred vision, diplopia, ptosis Management Pre-planned 'catnaps' throughout day, analeptics–ie, long-term stimulants–eg, methylphenidate, dextroamphetamine or tricyclic antidepressants that inhibit re-uptake of norepinephrine and serotonin; MAOIs may eventually cause tardive dyskinesia. See Insomnia, Narcolepsy tetrad, Sleep apnea syndrome, Sleep disorders.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A sleep disorder that usually appears in young adulthood, consisting of recurring episodes of sleep during the day, and often disrupted nocturnal sleep; frequently accompanied by cataplexy, sleep paralysis, and hypnagogic hallucinations; a genetically determined disease.
Synonym(s): Gélineau syndrome.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A disorder featuring an overwhelming tendency to fall asleep when relaxing or free from stimulating demands. People with narcolepsy may drop off many times a day and sleep for minutes to hours. The cause is unknown. Driving a car may be dangerous.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


Jean Baptiste Edouard, French physician, 1859-1906.
Gélineau disease - Synonym(s): Gélineau syndrome
Gélineau-Redlich syndrome - Synonym(s): Gélineau syndrome
Gélineau syndrome - a sleep disorder that usually appears in young adulthood. Synonym(s): Gélineau disease; Gélineau-Redlich syndrome; narcolepsy
Medical Eponyms © Farlex 2012


(nahr'kō-lep-sē) [MIM*161400]
Sleep disorder, mostly in young adults, with recurring diurnal episodes of sleep and often disrupted nocturnal sleep.
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about narcolepsy

Q. How do you wake up in the morning if your narcolepsy is so severe you can't hear the alarm clock, phone ring? biggest problem is sleep paralysis, can't wake up. Late for work, everything, life is suffering because of severity. Have tried ritalin, natural supplements, hypnosis therapy, Provigal, antidepressants, nothing seems to work. Employer thinks it's an excuse, friends are irritated, I'm at my wits end. Life is spent sleeping more than awake.

A. Narcolepsy cannot yet be cured. But EDS and cataplexy, the most disabling symptoms of the disorder, can be controlled in most patients with drug treatment. Often the treatment regimen is modified as symptoms change. For decades, doctors have used central nervous system stimulants-amphetamines such as methylphenidate, dextroamphetamine, methamphetamine, and pemoline-to alleviate EDS and reduce the incidence of sleep attacks. For most patients these medications are generally quite effective at reducing daytime drowsiness and improving levels of alertness. However, they are associated with a wide array of undesirable side effects so their use must be carefully monitored. Common side effects include irritability and nervousness, shakiness, disturbances in heart rhythm, stomach upset, nighttime sleep disruption, and anorexia. For full article: Hope this helps.

More discussions about narcolepsy
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References in periodicals archive ?
These brains were also compared with the brains of three narcoleptic mouse models and to the brains of narcoleptic dogs.
Altered function may result in cataplexy, the sudden muscular weakness which occurs in association with strong emotion in narcoleptics. GHB treatment has a high rate of success in reducing cataplexy, sleep attacks, sleep paralysis, and hypnagogic hallucinations.
With EDS being the most prevalent and the most problematic issue for narcoleptics, most of the treatments target this particular symptom (8).
The lack of HC-secreting cells is probably why most narcoleptics, unlike people who sleep normally, have undetectable levels of HC in the cerebrospinal fluid that bathes their brains.
Indeed, when Mignot's colleague Christelle Peyron studied brain tissue from two deceased narcoleptics, he was unable to find any nerve cells containing the genetic instructions to build the hypocretins.
With 180 narcoleptic participants, Broughton et al also documented narcolepsy's adverse affects on an individual's life and sense of wellbeing.[6-8] Rogers, meanwhile, examined the coping strategies twenty narcoleptics used to manage their symptoms and minimize illness-related problems.[23] The participants in these studies considered EDS and/or sleep attacks the most interfering of all narcoleptic symptoms on lifestyle.[6,23] While the majority (75-82%) of these narcoleptics held full-time jobs, problems such as reduced performance (due to sleepiness), fear of job loss and decreased promotional opportunities were reported.[6-23] Participants also reported difficulties with interpersonal relationships among family members and friends.
Because narcoleptics can spend several hours a day sleeping in advanced cases, it may be difficult for such individuals to hold jobs, drive, go shopping, or even do housework.
Narcoleptics may also suffer from hallucinations and double vision.
About 30%-60% of narcoleptic patients have sleep paralysis, a similar proportion have hypnagogic hallucinations, which occur at sleep onset.
Provigil has been found to be effective for narcoleptics - who can drop off to sleep without warning.
Though the condition provokes many jokes, narcolepsy can be a debilitating disorder: Narcoleptics sometimes fall asleep in the middle of conversations or physical activities.