DAYTIME SLEEP INERTIA IN NARCOLEPSY-CATAPLEXY

Eight volunteers with narcolepsy-cataplexy participated in a study of scheduled naps and performance. Sleep inertia was examined following f ive ''short'' naps of 5% and a single ''long'' nap of 25% of total 24- hour sleep time as determined by prior sleep log data. Contrary to som e subjective reports, short naps (mean duration of just under 30 minut es) were accompanied by sleep inertia in narcoleptics. As measured by the descending subtraction task, this sleep inertia was at times quite prolonged and lasted 20 minutes after waking from midday short naps, which ended on average at 1555 hours. In addition, sleep inertia, as m easured by both the descending subtraction task and the four-choice re action-time test, was evident throughout both afternoon and evening sh ort naps; however, it was completely absent from reaction-time test re sults immediately following the single long nap, which ended on averag e at 1640 hours. Sleep inertia was maximum after slow-wave sleep arous als and was minimal or absent following the first short nap, which als o contained the highest amount of rapid eye movement sleep of all naps .