What is a feature of narcolepsy

NarcolepsyThis is a disorder characterised by excessive daytime sleepiness, often disturbed night-time sleep and disturbances in the REM-sleep. The hallmark of this disorder is decreased REM latency, i.e. decreased latent period before the first REM period occurs. Normal REM latency is 90-100 minutes. In narcolepsy, REM-sleep usually occurs within 10 minutes of the onset of sleep. The common age of onset is 15-25 years, with usually a stable course throughout life. The prevalence rate of narcolepsy is about 4 per 10,000.The classic tetrad of symptoms is:i. Sleep attacks (most common):iii. Hypnagogic hallucinations:iv. Sleep paralysis (least common): Ref: A Sho Textbook of Psychiatry, Niraj Ahuja, 7th Edition, pg. no. 138