Continuous observation of EEG patterns at night and daytime of normal subjects under restrained conditions. I. Quiescent state when lying down.

Daytime EEGs are significantly influenced mainly by 3 factors: mental activity, behavior and surrounding circumstances. Since both behavior and circumstances can be controlled, this expertiment tried to stabilize these two factors, though not completely. Twenty healthy subjects (19--23 years old) participated in this study. The experiment started at about 11 p.m., with a sleep record of the subject until the next morning. After spontaneously awakening, the subjects were requested to maintain the same posture, lying on a bed in a sound-attenuated room, until the end of the experiment (8 p.m. the next day), and were asked not to fall asleep. EEGs were recorded without interruption throughout the experiment (21 h). Inspection of the EEGs, simultaneous monitoring of subject behavior on TV, and successive data analysis, resulted in the following tentative conclusions: (1) The subjects had a strong tendency to fall asleep in the daytime. The EEG records of the majority of the subjects showed that sleep occupied about 30--60% of their daytime activity. But the daytime sleep was not a 'miniature' of nocturnal sleep. (2) In the daytime phase, appearance of sleep onset REMs on the EEG were frequently observed in a majority of the subjects. (3) It was suggested that the REM cycle found in nocturnal sleep does not appear in the daytime phase. And another rhythm, a 4 h sleep-waking cycle, was suggested. (4) EEG findings, as well as reports of subjective experiences of an uncontrollable desire to fall asleep, were indicative of narcoleptic-like states in a majority of the subjects.