Narcolepsy

Symptoms:

Narcolepsy is a chronic sleep disorder whose main characteristic 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. In addition, nighttime sleep may be disrupted with frequent awakenings.

Three additional classic symptoms of narcolepsy are:

Cataplexy: sudden episodes of loss of muscle function, ranging from slight weakness 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. 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.

Cause:

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.

Who is affected?

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.

Diagnosis:

The Multiple Sleep Latency Test (MSLT) measures the speed of falling asleep. In this test, patients are given several opportunities to fall asleep during the course of a day when they would normally be awake. For each opportunity, the length of time to fall asleep is measured. People without sleep problems usually take an average of 10 to 20 minutes to fall asleep. Individuals who fall asleep in less than 5 minutes are likely to require some treatment for sleep disorders. The MSLT may be useful to measure the degree of excessive daytime sleepiness and to rule out other types of sleep disorders.

Treatment:

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. Employers can promote better working opportunities for individuals with narcolepsy by permitting special work schedules and nap breaks.

If possible, individuals with narcolepsy should avoid jobs that require driving long distances or handling hazardous equipment or that require alertness for lengthy periods.