Excessive daytime sleepiness is often result of self-imposed sleep deprivation espetially in young people. More often it is effect of disturbed nocturnal sleep or misaligned circadian rhytms. It may be side effect of many often-used drugs, for example hypnotics or alcohol. Nocturnal sleep disturbances, which lead to EDS, should be carefully assessed and treated. In several conditions EDS is not an outcome of night-sleep loss and should be considered as primary hypersomnia of central origin. These hypersomnias according to ICSD-2 include narcolepsy with or without cataplexy, recurrent hypersomnia, idiopathic hypersomnia with or without long sleep time and hypersomnias due to different medical and neurological conditions. Narcolepsy with cataplexy.
