narcolepsy

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Related Topics:: sleep; Adderall; sleep paralysis; cataplexy; sleep disorder

On the Web:: Harvard Health Publishing - Narcolepsy (Oct. 30, 2026)

narcolepsy

Q: What is narcolepsy?

Narcolepsy is a long-term neurological condition in which the brain struggles to properly control the boundaries between sleeping and waking, resulting in overwhelming daytime drowsiness and sudden, irresistible episodes of sleep .

Q: When does narcolepsy usually occur?

Narcolepsy usually occurs in youth or early adult life. Peak onset is around ages 15–25. Although most common in this age range, symptoms can start as early as age 2 or as late as 40 or 50.

Q: What is sleep paralysis in narcoleptics?

Sleep paralysis in narcolepsy is a common symptom where individuals temporarily cannot move or speak while falling asleep or waking up. It frequently is accompanied by vivid, frightening hallucinations .

Q: What causes narcolepsy?

Narcolepsy most often develops when the brain loses its supply of hypocretin (also known as orexin), which is a chemical messenger essential for maintaining alertness and stable sleep-wake patterns. In many cases, this loss appears to stem from an autoimmune response that mistakenly targets and damages specialized cells in the hypothalamus . The condition is thought to arise from a mix of genetic susceptibility, environmental influences such as infections , and immune system misfiring that ultimately disrupts the brain’s ability to sustain wakefulness.

sleep disturbance

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Oct. 30, 2026 •History

What is narcolepsy?

When does narcolepsy usually occur?

What is sleep paralysis in narcoleptics?

What causes narcolepsy?

narcolepsy, long-term neurological condition in which the brain struggles to properly control the boundaries between sleeping and waking, resulting in overwhelming daytime drowsiness and sudden, irresistible episodes of sleep.

The syndrome usually occurs in youth or early adult life. The narcoleptic can fall asleep anywhere, anytime—while in conversation, at work, while eating, and even when standing or walking. Sleep may last a few seconds or several minutes, rarely for more than an hour, and the narcoleptic is easily awakened to an alert state. Narcoleptics may also experience sleep paralysis, which normally occurs as one is either falling asleep or awakening. Although mentally alert, the narcoleptic experiencing sleep paralysis is totally unable to move for a very brief period.

Most narcoleptics experience REM sleep (rapid eye movement sleep) at the onset of sleep. This differs from typical sleep staging, in which REM occurs about 90 minutes after sleep onset. Associated with narcolepsy is cataplexy, a brief impairment of muscle tone such as a limpness of the arms or legs.

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There are two forms of narcolepsy, type 1 and type 2. Narcolepsy type 1 is primarily caused by the loss of neurons in the hypothalamus that specialize in the production of a hormone known as hypocretin (also known as orexin), which promotes wakefulness. The loss of hypocretin may in turn be linked to an underlying autoimmune disorder in which immune cells target the hormone for destruction. In some persons, autoimmunity against hypocretin is suspected to occur as a result of variations in genes that regulate cellular immunity. Narcolepsy type 2 does not feature cataplexy and often is less severe than type 1. Patients with type 2 narcolepsy also usually have healthy hypocretin levels.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Kara Rogers.

narcolepsy

What is narcolepsy?

When does narcolepsy usually occur?

What is sleep paralysis in narcoleptics?

What causes narcolepsy?

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