Narcolepsy 375
before or upon falling asleep or hypnopompic  hallucinations just after awakening. These
hallucinations are distinct from the less vivid, nonhallucinatory dreamlike mentation at
sleep onset that occurs in normal sleepers.  Nightmares and vivid dreaming are also fre-
quent in narcolepsy, as is REM sleep behavior disorder. Approximately 20%–60% of indi-
viduals experience sleep paralysis upon falling asleep or awakening, leaving them awake
but unable to move or speak. However, many  normal sleepers also report sleep paralysis,
especially with stress or slee p deprivation. Nocturnal eating  may occur. Obesity is com-
mon. Nocturnal sleep disruption with freque nt long or short awakenings is common and
can be disabling.
Individuals may appear sleepy or fall asleep in the waiting area or during clinical ex-
amination. During cataplexy, individuals may slump in a chair and have slurred speech or
drooping eyelids. If the clinician has time to  check reflexes during cataplexy (most attacks
are less than 10 seconds), reflexes are abo lished—an important finding distinguishing gen-
uine cataplexy from conversion disorder. 
Prevalence
Narcolepsy-cataplexy affects 0.02%–0.04% of the general population in most countries.
Narcolepsy affects both genders, with possibly a slight male preponderance. 
Development and Course 
Onset is typically in children and adolescents/young adults but rarely in older adults.
Two peaks of onset are suggested, at ages 15–25 years and ages 30–35 years. Onset can be
abrupt or progressive (over years). Severity is highest when onset is abrupt in children,