The effect of self-awakening from nocturnal sleep on sleep inertia.

The present study examined the effects of self-awakening on sleep inertia after nocturnal sleep. Ten undergraduate and graduate students participated in the study. Their polysomnograms were recorded for five consecutive nights; the first, second, and third to fifth nights were adaptation, forced-awakening, and self-awakening nights, respectively. Participants rated sleepiness, fatigue, comfort, and work motivation, and these ratings were followed by switching (7 min) and auditory reaction time tasks (6 min), both before bedtime (15 min) and immediately after awakening (4 min x 15 min). Although reaction times on the auditory were task prolonged, and participants complained of feeling uncomfortable immediately after forced-awakening, reaction times were shortened after self-awakening, and the participants did not complain of feeling uncomfortable on these nights. The results of this study suggest that sleep inertia occurs after forced-awakening and that it can be prevented by self-awakening.