Continuous observations of daytime EEG patterns in normal subjects under restrained conditions while sitting in...

While stabilizing both behavioral and environmental factors as far as possible, continuous EEG observations were made on the level of consciousness of 32 normal healthy subjects aged 19-23. The experiment started at 11 p.m. by obtaining the sleep record for each subject. After spontaneous awakening in the morning, each subject was requested to maintain the same posture while sitting in an armchair or on a stool until the end of the experiment, and was asked not to fall asleep in the daytime. The behaviors of each subject were continuously video-recorded throughout the period of the experiment. From inspection of the EEG records, simultaneous video monitoring and recording of the subjects' daytime behavior, and the subsequent data analysis, the following conclusions were drawn: 1) The subjects had a strong tendency to fall asleep in the restrained armchair-sitting posture during the daytime. The EEG and video records of the subjects showed that sleep accounted for about 25-55% (average 37.6%) of the daytime period. 2) In 23 recordings of the subjects sitting in an armchair, 109 sleep blocks were observed, in comparison with 42 sleep blocks while sitting on a stool. On the basis of their characteristics, the sleep blocks could be divided into five categories. All the five types of sleep blocks were observed in the armchair-sitting posture, but only NREM-REM and SOREMP types of a short duration were observed in the stool-sitting posture. SOREMPs were observed in the daytime in both postures. 3) The REM cycle found in nocturnal sleep did not appear in the daytime. However, another rhythm, a 4-hour waking-sleep cycle after spontaneous awakening, was observed.