Narcolepsy

Definition:

A sleep disorder associated with uncontrollable sleepiness and frequent daytime sleeping.

Causes, incidence, and risk factors:

Narcolepsy (sleeping sickness) affects both men and women. It is usually diagnosed between ages 15 and 25. It affects both sexes equally. The severity of the disorder usually levels off after about age 30.

The exact cause of narcolepsy is unknown. Research studies have indicated that the disorder may be genetic, with studies showing gene markers that may indicate a tendency to develop narcolepsy. The cause is a problem with the sleep-wake mechanisms in the brain. The condition may be aggravated by conditions that cause insomnia, such as disruption of work schedules.

Narcolepsy is characterized by episodes of frequent, uncontrollable daytime sleeping, usually preceded by drowsiness. The episodes usually occur after meals but may occur while working or driving a vehicle, having a conversation, or in any sedentary or boring situation. There is a brief period of sleep and the person awakens feeling refreshed. However, they may again become uncontrollably sleepy a short time later.

Narcolepsy may be associated with cataplexy, a brief episode of severe loss of tone of various muscles. Generalized weakness may occur for a few moments during the transition between sleep and wake (sleep-paralysis). Many persons with narcolepsy also have dream-like hallucinations in the transition between sleep and wakefulness.