Clinical characteristics of essential hypersomnia syndrome

In order to clarify the difference in clinical characteristics between narcolepsy-like hypersomnia without cataplexy, which is called essential hypersomnia syndrome (EHS), and narcolepsy, we compared background variables, symptoms and treatment outcomes between 19 EHS patients and 20 narcoleptic patients. The results indicated significantly milder rapid eye movement (REM)-related symptoms, longer sleep latencies on multiple sleep latency test and smaller dosages of psycho-stimulants for suppressing daytime sleepiness in EHS than in narcolepsy. Positive findings of HLA-DQB1*0602 were recognized in less than 40% of EHS patients. We speculated that EHS would form a subgroup of hypersomnia in which disease severity is milder, and treatment response is better than typical narcolepsy.