Narcolepsy

A sleep disorder whose primary symptom is irresistible attacks of sleepiness during the daytime.

Narcolepsy, which usually begins in adolescence or early adulthood, affects about one in every 1,000 persons and is equally common in males and females. The sleep attacks, which can occur anywhere from six to 20 times a day, usually last about 10 to 20 minutes but can persist for as long as two to three hours. Narcolepsy is diagnosed if sleep attacks occur every day for at least three months (although most people treated for the disorder suffer from it for a much longer period of time—often years—before seeking help). In addition to the sleep attacks, persons suffering from narcolepsy often display several other characteristic symptoms. The most debilitating of these is cataplexy, a sudden loss of muscle tone that can affect a part or all of the body. Cataplectic attacks range from a sagging jaw or drooping head to a total collapse that causes the person to fall to the ground. Affecting about 70% of narcoleptics, they are usually triggered by strong emotions, ranging from fear and anger to excitement and amusement (laughter often provokes cataplectic attacks). Respiration is not affected, and full consciousness is maintained throughout the episode. Usually the attacks only last a few seconds, after which normal muscle strength returns. Other symptoms of narcolepsy include vivid dreamlike imagery while waking or falling asleep, episodes of sleep paralysis (in which the person wakes but is temporarily unable to move), and automatic behavior (sleepwalking-type actions which are performed without the person's conscious knowledge).

The cause of narcolepsy is not known, but sleep researchers believe it comes from a malfunction of the mechanism in the brain that regulates sleeping and waking, especially the regulation of REM (rapid eye movement) sleep, the part of the sleep cycle associated with dreaming. It is also known that there is a hereditary component to narcolepsy: having a narcoleptic parent dramatically increases one's chances of developing the disorder, from the normal 1 in 1,000 to 1 in 20. In recent research, a genetic marker has been found in the blood of over 95% of narcolepsy sufferers who were tested for it. Narcolepsy may also develop as a consequence of brain damage caused by injury or disease.

Narcolepsy is a chronic illness that lasts throughout a person's lifetime and has no known cure. Napping during the daytime can reduce the number of sleep attacks by lessening sleepiness. For those severely affected by the disorder, stimulants such as methylphenidate (Ritalin) and Dexedrine have been prescribed to ward off sleep attacks. Cataplexy—thought to be a partial intrusion of REM sleep into the waking state—has been treated with medications known to suppress REM sleep, such as tricyclic antidepressants. Doctors have had good results with another medication, the experimental drug gamma-hydroxybutyrate, prescribed for narcoleptics to improve the quality of their nighttime sleep, which is usually fitful and fragmented. The resulting improvement of nighttime sleep has had marked success in the reduction (and in some cases complete remission) of symptoms, including both daytime sleep attacks and cataplexy. To avoid the potential danger and embarrassment of cataleptic episodes, some persons with narcolepsy try to control the emotions that trigger them, even avoiding situations that are likely to bring on these emotions.

Narcolepsy has a crippling effect on the lives of those afflicted with it, causing disruption, embarrassment, and, potentially, danger in their everyday lives and interfering with both work and family life. Self-help groups sponsored by the American Narcolepsy Association (and a similar group in Canada) offer support to narcoleptics and their families. These organizations also work to help raise public awareness about the disorder.