ABSTRACT
Narcolepsy is a relatively rare disorder with a prevalence of 0.02-0.05%, depending on the population studied. It may be more frequent in Japan (prevalence of 0.18%) and is very rare in Israel (0.002%). It is manifested by abnormal sleepiness, disturbed nocturnal sleep and pathological manifestations of REM sleep. In the 1930s, Daniels described the classic tetrad of daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucinations. The onset of clinical manifestations of narcolepsy, although variable, are typically during the second decade of life. The primary symptom is excessive sleepiness, which manifests itself as irresistible episodes of drowsiness or sleep that occur both during monotonous activities and when actively engaged. The sleepiness is classically relieved by brief naps, from which the patient awakens feeling refreshed, only to have sleepiness return within several hours. The other commonly associated symptoms represent manifestations of abnormal REM sleep.
