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Facts About Narcolepsy
What Is Narcolepsy?
Narcolepsy is a chronic sleep disorder with no known cause. The main characteristic of
narcolepsy is excessive and overwhelming daytime sleepiness, even after adequate nighttime
sleep. A person with narcolepsy is likely to become drowsy or to fall asleep, often at
inappropriate times and places. Daytime sleep attacks may occur with or without warning
and may be irresistible. These attacks can occur repeatedly in a single day. Drowsiness
may persist for prolonged periods of time. In addition, nighttime sleep may be fragmented
with frequent wakenings.
Three other classic symptoms of narcolepsy, which may not occur in all patients, are:
- Cataplexy: sudden episodes of loss of muscle function, ranging from slight weakness
(such as limpness at the neck or knees, sagging facial muscles, or inability to speak
clearly) to complete body collapse. Attacks may be triggered by sudden emotional reactions
such as laughter, anger, or fear and may last from a few seconds to several minutes. The
person remains conscious throughout the episode.
- Sleep paralysis: temporary inability to talk or move when falling asleep or waking up.
It may last a few seconds to minutes.
- Hypnagogic hallucinations: vivid, often frightening, dream-like experiences that occur
while dozing or falling asleep.
Daytime sleepiness, sleep paralysis, and hypnagogic hallucinations can also occur in
people who do not have narcolepsy.
In most cases, the first symptom of narcolepsy to appear is excessive and overwhelming
daytime sleepiness. The other symptoms may begin alone or in combination months or years
after the onset of the daytime sleep attacks. There are wide variations in the
development, severity, and order of appearance of cataplexy, sleep paralysis, and
hypnagogic hallucinations in individuals. Only about 20 to 25 percent of people with
narcolepsy experience all four symptoms. The excessive daytime sleepiness generally
persists throughout life, but sleep paralysis and hypnagogic hallucinations may not.
The symptoms of narcolepsy, especially the excessive daytime sleepiness and cataplexy,
often become severe enough to cause serious disruptions in a person's social, personal,
and professional lives and severely limit activities.
When Should You Suspect Narcolepsy?
You should be checked for narcolepsy if:
- you often feel excessively and overwhelmingly sleepy during the day, even after having
had a full night's sleep;
- you fall asleep when you do not intend to, such as while having dinner, talking,
driving, or working;
- you collapse suddenly or your neck muscles feel too weak to hold up your head when you
laugh or become angry, surprised, or shocked;
- you find yourself briefly unable to talk or move while falling asleep or waking up.
How Common Is Narcolepsy?
Although it is estimated that narcolepsy afflicts as many as 200,000 Americans, fewer
than 50,000 are diagnosed. It is as widespread as Parkinson's disease or multiple
sclerosis and more prevalent than cystic fibrosis, but it is less well known. Narcolepsy
is often mistaken for depression, epilepsy, or the side effects of medications.
Who Gets Narcolepsy?
Narcolepsy can occur in both men and women at any age, although its symptoms are
usually first noticed in teenagers or young adults. There is strong evidence that
narcolepsy may run in families; 8 to 12 percent of people with narcolepsy have a close
relative with the disease.
What Happens in Narcolepsy?
Normally, when an individual is awake, brain waves show a regular rhythm. When a person
first falls asleep, the brain waves become slower and less regular. This sleep state is
called non-rapid eye movement (NREM) sleep. After about an hour and a half of NREM sleep,
the brain waves begin to show a more active pattern again, even though the person is in
deep sleep. This sleep state, called rapid eye movement (REM) sleep, is when dreaming
occurs.
In narcolepsy, the order and length of NREM and REM sleep periods are disturbed, with
REM sleep occurring at sleep onset instead of after a period of NREM sleep. Thus,
narcolepsy is a disorder in which REM sleep appears at an abnormal time. Also, some of the
aspects of REM sleep that normally occur only during sleep--lack of muscle tone, sleep
paralysis, and vivid dreams--occur at other times in people with narcolepsy. For example,
the lack of muscle tone can occur during wakefulness in a cataplexy episode. Sleep
paralysis and vivid dreams can occur while falling asleep or waking up.
How Is Narcolepsy Diagnosed?
Diagnosis is relatively easy when all the symptoms of narcolepsy are present. But if
the sleep attacks are isolated and cataplexy is mild or absent, diagnosis is more
difficult.
Two tests that are commonly used in diagnosing narcolepsy are the polysomnogram and the
multiple sleep latency test. These tests are usually performed by a sleep specialist. The
polysomnogram involves continuous recording of sleep brain waves and a number of nerve and
muscle functions during nighttime sleep. When tested, people with narcolepsy fall asleep
rapidly, enter REM sleep early, and may awaken often during the night. The polysomnogram
also helps to detect other possible sleep disorders that could cause daytime sleepiness.
For the multiple sleep latency test, a person is given a chance to sleep every 2 hours
during normal wake times. Observations are made of the time taken to reach various stages
of sleep. This test measures the degree of daytime sleepiness and also detects how soon
REM sleep begins. Again, people with narcolepsy fall asleep rapidly and enter REM sleep
early.
How Is Narcolepsy Treated?
Although there is no cure for narcolepsy, treatment options are available to help
reduce the various symptoms. Treatment is individualized depending on the severity of the
symptoms, and it may take weeks or months for an optimal regimen to be worked out.
Complete control of sleepiness and cataplexy is rarely possible. Treatment is primarily by
medications, but lifestyle changes are also important. The main treatment of excessive
daytime sleepiness in narcolepsy is with a group of drugs called central nervous system
stimulants. For cataplexy and other REM-sleep symptoms, antidepressant medications and
other drugs that suppress REM sleep are prescribed. Caffeine and over-the-counter drugs
have not been shown to be effective and are not recommended.
In addition to drug therapy, an important part of treatment is scheduling short naps
(10 to 15 minutes) two to three times per day to help control excessive daytime sleepiness
and help the person stay as alert as possible. Daytime naps are not a replacement for
nighttime sleep.
Ongoing communication among the physician, the person with narcolepsy, and family
members about the response to treatment is necessary to achieve and maintain the best
control.
What Is Being Done To Better Understand Narcolepsy?
Studies supported by the National Institutes of Health (NIH) are trying to increase
understanding of what causes narcolepsy and improve physicians' ability to detect and
treat the disease. Scientists are studying narcolepsy patients and families, looking for
clues to the causes, course, and effective treatment of this sleep disorder. Recent
discovery of families of dogs that are naturally afflicted with narcolepsy has been of
great help in these studies. Some of the specific questions being addressed in
NIH-supported studies are the nature of genetic and environmental factors that might
combine to cause narcolepsy and the immunological, biochemical, physiological, and
neuromuscular disturbances associated with narcolepsy. Scientists are also working to
better understand sleep mechanisms and the physical and psychological effects of sleep
deprivation and to develop better ways of measuring sleepiness and cataplexy.
How Can Individuals and Their Families and Friends Cope With Narcolepsy?
Learning as much about narcolepsy as possible and finding a support system can help
patients and families deal with the practical and emotional effects of the disease,
possible occupational limitations, and situations that might cause injury. A variety of
educational and other materials are available from sleep medicine or narcolepsy
organizations. Support groups exist to help persons with narcolepsy and their families.
Individuals with narcolepsy, their families, friends, and potential employers should
know that:
- Narcolepsy is a life-long condition that requires continuous medication.
- Although there is not a cure for narcolepsy at present, several medications can help
reduce its symptoms.
- People with narcolepsy can lead productive lives if they are provided with proper
medical care.
- If possible, individuals with narcolepsy should avoid jobs that require driving long
distances or handling hazardous equipment or that require alertness for lengthy periods.
- Parents, teachers, spouses, and employers should be aware of the symptoms of narcolepsy.
This will help them avoid the mistake of confusing the person's behavior with laziness,
hostility, rejection, or lack of interest and motivation. It will also help them provide
essential support and cooperation.
- Employers can promote better working opportunities for individuals with narcolepsy by
permitting special work schedules and nap breaks.
For More Information
For additional information on sleep and sleep disorders, contact the following offices
of the National Heart, Lung, and Blood Institute of the National Institutes of Health:
National Center on Sleep Disorders Research (NCSDR)
The NCSDR supports research, scientist training, dissemination of health information, and
other activities on sleep and sleep disorders. The NCSDR also coordinates sleep research
activities with other Federal agencies and with public and nonprofit organizations.
National Center on Sleep Disorders Research
Two Rockledge Centre
Suite 7024
6701 Rockledge Drive,
MSC 7920 Bethesda, MD
20892-7920
(301) 435-0199
(301) 480-3451 (fax)
National Heart, Lung, and Blood Institute Information Center
The Information Center acquires, analyzes, promotes, maintains, and disseminates
programmatic and educational information related to sleep and sleep disorders. Write for a
list of available publications or to order additional copies of this fact sheet.
NHLBI Information Center
P.O. Box 30105
Bethesda, MD
20824-0105
(301) 251-1222
(301) 251-1223 (fax)
For more information about narcolepsy and patient support groups, contact the
Narcolepsy Network at P.O. Box 42460, Cincinnati, OH 45242.
U.S. Department of Health and Human Services
Public Health Service
National Institutes of Health
National Heart, Lung, and Blood Institute
NIH Publication No. 96-3649
October 1996
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