Clinical and Polysomnographic Comparison between Narcolepsy without Cataplexy and Idiopathic Hypersomnia

Many patients report symptoms of hypersomnia with mostly excessive daytime sleepiness. According to the second edition of the International Classification of Sleep Disorders (ICSD2), hypersomnias of central origin are categorized as narcolepsy and idiopathic hypersomnia (IH).1 And narcolepsy can be divided into two categories based on the existence of cataplexy as narcolepsy with cataplexy (NTC) and narcolepsy without cataplexy (NATC). The symptoms of narcolepsy including abnormal sleep tendencies such as excessive daytime sleepiness (EDS), disturbed nocturnal sleep, sleep paralysis and hypnopompic or hypnagogic hallucinations can occur in any person who is severely sleep deprived, and only cataplexy is unique to narcolepsy.2 Narcolepsy with cataplexy can be diagnosed easier than other hypersomnia of central origin. But narcolepsy without cataplexy can be more complicated for the diagnosis and the differential diagnosis from idiopathic hypersomnia because it only manifests EDS subjectively Received: June 27, 2013 Revised: October 14, 2013 Accepted: October 17, 2013