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Narcolepsy is a chronic central nervous system (CNS) disorder that causes patients to suddenly fall asleep, often at unexpected moments. The sleep disorder is the result of a malfunction in the brain that prevents the proper regulation of sleep-wake cycles.

Patients with narcolepsy feel drowsy much of the time and generally find it difficult to remain awake for extended periods. Though they do not sleep more often than other people do, their bodies are unable to properly control the normal boundaries between sleeping and waking. Narcolepsy can be hazardous if a patient falls asleep while driving or climbing stairs.

There are four stages of non-rapid eye movement sleep that progress from light to deep. Following these stages is rapid eye movement (REM) sleep, a stage in which a person’s muscles are temporarily paralyzed and dreaming occurs. Initially, brain waves slow down for an hour or two before brain activity picks up again, leading to REM sleep. People who are asleep typically alternate between non-REM sleep and REM sleep throughout the night.

In contrast, people with narcolepsy quickly fall into REM sleep, often at unexpected moments. They also experience symptoms that occur in most people at other times of the sleep cycle. These include a relaxation of muscle tone (cataplexy), a temporary inability to move (sleep paralysis) and intense dreaming.

People with narcolepsy may also have other sleep disorders such as sleepwalking and/or mood disorders such as depression.

Patients may go many years before realizing that they have developed narcolepsy. They accept the daytime drowsiness as a part of life, not realizing it may be a more serious condition. Many do not seek treatment until other more disturbing symptoms such as cataplexy appear. Narcolepsy is incurable. However, effective forms of treatment can help patients to control their symptoms and to live full lives.