The clinical spectrum of narcolepsy and idiopathic hypersomnia.

To better define the clinical spectra of narcolepsy and idiopathic hypersomnia, we retrospectively compared clinical and polygraphic findings and questionnaire results in groups of subjects with narcolepsy with or without cataplexy, idiopathic hypersomnia, insufficient sleep syndrome, mild sleep apnea, and excessive daytime sleepiness not otherwise specified. Sleep paralysis and sleep-related hallucinations were most frequent in narcolepsy-cataplexy, but their frequency did not differ between narcolepsy without cataplexy and idiopathic hypersomnia. Mean durations of nocturnal sleep, daytime naps, and morning grogginess were not increased in idiopathic hypersomnia compared with other groups. Among subjects without cataplexy, symptoms of sleep paralysis and sleep-related hallucinations were equally common in subjects with and without frequent sleep-onset REM periods. These findings suggest that the occurrence of these symptoms in subjects without classical narcolepsy-cataplexy is a function of factors other than a propensity for early onset of REM sleep and indicate a need to reevaluate diagnostic criteria for narcolepsy and idiopathic hypersomnia.