Repeated nocturnal sleep latencies in narcoleptic, sleepy and alert subjects

Objectives: The purpose of this study was to assess nocturnal sleep latenci es among narcoleptics. Methods: Thirteen narcoleptics and matched sleepy and alert controls partic ipated in this study. Subjects were awakened three times on each of two exp erimental nights. The latencies to sleep and rapid eye movement sleep were evaluated at the beginning of the night and following each experimental awa kening. Results: The alert group (AG) had a significantly longer mean nocturnal sle ep latency than the narcoleptic (NG) and sleepy groups (SG). The sleep late ncies at 23:00 and 01:10 h were significantly longer than the latencies at 03:10 and 05:10 h. The interaction between group and time of night demonstr ated longer latencies at 23:00 and 03:10 h for the AG when compared to the SG and the NG. At 01:10 and 05:10 h all groups had comparable latencies. Th e number of subjects in the NG who had multiple sleep onset REM periods (SO REMPs) was significantly higher than in either the AG or the SG. Conclusions: Narcoleptics were found to have a heightened propensity to fal l asleep and increased number of SOREMPs during nocturnal sleep opportuniti es. These characteristics are consistent with the daytime polysomnographic findings known in this patient population. (C) 1999 Elsevier Science Irelan d Ltd. All rights reserved.