Perhaps one of the most famous and disturbing sleep disorders is narcolepsy — the condition in which a seemingly fully alert person suddenly and without warning becomes drowsy and falls asleep. Narcolepsy occurs in approximately 1 in 2000 Americans. The cardinal symptom of narcolepsy is excessive daytime sleepiness which leads to an irrepressible need to sleep.

Other symptoms include sudden muscle weakness when experiencing an intense emotion such as laughter (cataplexy), vivid dream-like hallucinations while falling asleep or when waking up (hyponagogic and hypnopompic hallucinations), and feeling completely paralyzed when waking up or falling asleep (sleep paralysis). These symptoms can develop suddenly or over many years. Narcolepsy often takes years to recognize in patients since many medical conditions present with fatigue as a symptom.

While the cause of narcolepsy is not completely understood, current research points to a combination of genetic and environmental factors that affect the immune system. Most patients with narcolepsy have a deficiency of the neurotransmitter orexin in the brain.

To diagnose narcolepsy, a set of sleep studies is performed: an overnight diagnostic polysomnography followed by a multiple sleep latency test the next day. Narcolepsy can be dangerous. It causes persistent sleepiness and even “sleep attacks” where individuals unwillingly fall asleep during work, at school, while eating, or even while driving. Individuals with untreated narcolepsy are 10 times more likely to be involved in a motor vehicle accident than those who receive treatment.

Narcolepsy can be managed. Medications and lifestyle changes can help improve sleep quality, reduce daytime sleepiness, and enhance the quality of life.