Etude electroencephalographique et polygraphique du sommeil d'apres-midi chez le sujet normal

Abstract

The aim of this work was to study the spontaneous afternoon sleep of normal subjects. Twelve subjects were investigated on 2 consecutive afternoons, using 6 EEG and 6 polygraphic derivations (2 for eye movements, 1 for tone, 1 for respiration, 1 for the electrocardiogram and 1 for the electrodermogram). The interpretation also took account of the classic findings, in particular the phasic and nonphasic aspects of fast sleep, of the slow eye movements of going to sleep, of the average occipital frequency at the beginning of the recording and of the changes in respiration and muscle tone. We found that: 12 out of 24 afternoons showed at least one phase of fast sleep; afternoons with fast sleep showed a longer total sleep than afternoons without it (in the latter case the proportion of stages 1 and 2 was greater than in the former); the presence of fast sleep was linked with a certain minimal length of slow sleep and was always preceded by deep slow sleep; the average relationship between the duration of phasic periods and of total fast sleep was practically identical with that encountered during night sleep; going to sleep was faster in the afternoon than at night and also the periods with slow eye movements were more numerous in the afternoon; there were variations in the respiratory rhythm during slow sleep and also atonic periods, particularly during deep slow sleep; the recall of dream activities (experienced as such by the subjects) was possible even after sleep without rapid eye movements.