Most people with narcolepsy also experience cataplexy, sudden muscular weakness without loss of consciousness, which usually accompanies laughter or anger. Other symptoms, occurring just after falling asleep or upon awakening, include sleep paralysis (a feeling that one cannot move) and vivid hallucinations.
The cause of narcolepsy is not known with certainty, and there is no cure. Treatment, including regular planned naps and the use of stimulant drugs (e.g., amphetamines) plus antidepressants for cataplexy, can help to control its symptoms.
Sleep disorder with sudden, uncontrollable spells of daytime sleep and disturbances of nighttime sleep. It usually begins in youth or early adulthood and is presumably due to dysfunction of certain brain structures. Narcoleptics can fall asleep anywhere and anytime—for instance, while talking, eating, or driving. Sleep usually lasts a moment, rarely over an hour, and the narcoleptic is easily awakened. Sleep paralysis, normal when falling asleep or waking, occurs during full consciousness in narcolepsy, with brief but complete inability to move.
Learn more about narcolepsy with a free trial on Britannica.com.