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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 anytimefor 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.
This entry comes from Encyclopædia Britannica Concise. For the full entry on narcolepsy, visit Britannica.com.