1987 Volume 5 Issue 1 Pages 21-28
The fluctuations of daytime sleepiness were studied in 8 male subjects (20-22 y). After nocturnal sleep (23 : 00-07 : 00), subjects were assessed their daytime sleepiness at 30-min intervals (08 : 00-19 : 00) by three measures ; Multiple Sleep Latency Test (MSLT), Kwansei-Gakuin Sleepiness Scale (KSS) and EEG. MSLT scores and amplitudes of the theta and the alpha bands of Cz EEG showed significant periodicity of approximately 90 min corresponding to basic rest activity cycle (BRAC). KSS scores and amplitudes of the delta band of EEG showed much slower rhythms than 90 min. These data show that daytime sleepiness fluctuates with ultradian rhythms. The variations of periodicity amomg the five indices suggest that the fluctuations of daytime sleepiness are composite of multiple factors.
