Narcolepsy: Sleep Disorders

Content provided by the Faculty of the Harvard Medical School

Narcolepsy

Narcolepsy is a disorder of sleep/wake regulation whose hallmark is daytime sleepiness. A variety of other symptoms may also be present, but abnormalities of REM sleep seem to underlie each one. Instead of occurring normally — after a steady progression through the other stages of sleep — REM sleep intrudes at unusual and unwelcome times, such as immediately after sleep begins, as soon as a person lies down, or even in the midst of daytime activities.

Willpower or better nighttime sleep habits cannot overcome the profound drowsiness of narcolepsy. As a result, people with narcolepsy often have great trouble completing tasks.

About 1 in 2,000 people have this condition. It affects both sexes and all races in equal measure. Having a close relative with narcolepsy raises one's risk to about 1 in 100, but it's not strictly genetic. If one identical twin has it, the other's risk is 1 in 4.

Narcolepsy usually becomes apparent during adolescence or young adulthood, although symptoms sometimes appear in early childhood or middle age. On average, it takes five years of symptoms and visits to five physicians before a diagnosis of narcolepsy is made. This is because sleepiness may be the only symptom, or cataplectic attacks (see "Cataplexy") may be misdiagnosed as epilepsy or fainting.

Last updated:	January 23, 2007