行動的覚醒維持法によるマイクロスリープの実験的検討

Microsleep is usually defined as a sudden, short-lasting burst of stage 1 sleep although it is still left open whether the phenomenon should be considered as sleep. With all clinical observations, such as automatic behavior syndrome in hypersomniacs and mood and cognitive psychomotor performance in depressed patients, few basic experimental researches have been attempted on microsleep. The present study was aimed at examining the appearance of microsleep by using a behavioral maintenance of wakefulness test where subjects were instructed to perform a dual alternation task of finger tappings for 40 minutes: Right-hand tapping was performed successively 10 times and then switched into left-hand tapping, which in turn was followed by right-hand one and so on. The results indicated the specific state to microsleep was present, behaviorally characterized as the repeated occurrence of mistakes and corrections of tapping movements against the physiological background of intermitted EEG alpha activity and frequent slow eye movements. Microsleep seems to last roughly from 2 to 7 seconds, judging from delays of inter-tap intervals and alternation gaps between both hands.