narcolepsy.

" -a chronic sleep disorder, or dyssomnia, characterized by excessive daytime sleepiness (EDS) in which a person experiences extreme fatuque and possibly falls asleep at inappropriate times, such as while at work or at school. Narcoleptics usually experience disturbed nocturnal sleep and an abnormal daytime sleep pattern, which is often confused with insomnia. When a narcoleptic falls asleep they generally experience the REM stage of sleep within 10 minutes; whereas most people do not experience REM sleep until after 30 minutes. There is little evidence to suggest that narcoleptics tend to have a shorter life span."