Repeated nocturnal sleep latencies in narcoleptic, sleepy and alert subjects.

OBJECTIVES

The purpose of this study was to assess nocturnal sleep latencies among narcoleptics.

METHODS

Thirteen narcoleptics and matched sleepy and alert controls participated in this study. Subjects were awakened three times on each of two experimental nights. The latencies to sleep and rapid eye movement sleep were evaluated at the beginning of the night and following each experimental awakening.

RESULTS

The alert group (AG) had a significantly longer mean nocturnal sleep latency than the narcoleptic (NG) and sleepy groups (SG). The sleep latencies 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 demonstrated 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. The number of subjects in the NG who had multiple sleep onset REM periods (SOREMPs) was significantly higher than in either the AG or the SG.

CONCLUSIONS

Narcoleptics were found to have a heightened propensity to fall asleep and increased number of SOREMPs during nocturnal sleep opportunities. These characteristics are consistent with the daytime polysomnographic findings known in this patient population.