Narcolepsy is a chronic neurological disorder caused by the brain's inability to regulate sleep-wake cycles normally. At various times throughout the day, people with narcolepsy experience fleeting urges to sleep. If the urge becomes overwhelming, individuals will fall asleep for periods lasting from a few seconds to several minutes. In rare cases, some people may remain asleep for an hour or longer. In addition to excessive daytime sleepiness (EDS), three other major symptoms frequently characterize narcolepsy: cataplexy, or the sudden loss of voluntary muscle tone; vivid hallucinations during sleep onset or upon awakening; and brief episodes of total paralysis at the beginning or end of sleep. Narcolepsy is not definitively diagnosed in most patients until 10 to 15 years after the first symptoms appear. The cause of narcolepsy remains unknown. It is likely that narcolepsy involves multiple factors interacting to cause neurological dysfunction and sleep disturbances.

There is no cure for narcolepsy. In 1999, after successful clinical trial results, the FDA approved a drug called modafinil for the treatment of EDS. Two classes of antidepressant drugs have proved effective in controlling cataplexy in many patients: tricyclics (including imipramine, desipramine, clomipramine, and protriptyline) and selective serotonin reuptake inhibitors (including fluoxetine and sertraline). Drug therapy should be supplemented by behavioral strategies. For example, many people with narcolepsy take short, regularly scheduled naps at times when they tend to feel sleepiest. Improving the quality of nighttime sleep can combat EDS and help relieve persistent feelings of fatigue. Among the most important common-sense measures people with narcolepsy can take to enhance sleep quality are actions such as maintaining a regular sleep schedule, and avoiding alcohol and caffeine-containing beverages before bedtime. On July 17, 2002, the FDA approved Xyrem (sodium oxybate or gamma hydroxybutyrate, also known as GHB) for treating people with narcolepsy who experience episodes of cataplexy. Due to safety concerns associated with the use of this drug, the distribution of Xyrem is tightly restricted.

None of the currently available medications enables people with narcolepsy to consistently maintain a fully normal state of alertness. But EDS and cataplexy, the most disabling symptoms of the disorder, can be controlled in most patients with drug treatment. Often the treatment regimen is modified as symptoms change. Whatever the age of onset, patients find that the symptoms tend to get worse over the two to three decades after the first symptoms appear. Many older patients find that some daytime symptoms decrease in severity after age 60.

Prepared by the National Institutes of Health