Afternoon sleep in sensory deprivation: An EEG and polygraphic investigation in man

Abstract

This paper is concerned with modifications induced by sensory deprivation (SD) in afternoon sleep of normal subjects. EEG and polygraphy (eye movements, tonus, respiration, EKG and electrodermogram) were recorded in eight subjects. Recordings were visually analyzed, page by page, and sleep was divided into slow sleep (SS) and fast sleep (FS), the latter being subdivided into phasic (with REMs) and non-phasic (without REMs) FS. A quantitative analysis evaluated the slow eye movements (SEM) and the early variations of occipital frequency. In the SD situation, as compared to normal situation, sleep onset occurs later, SEMs during Stage 1 are more frequent, total sleep duration is slightly modified, SS lasting longer only when FS phases are present. The quantity of FS, particularly of phasic elements, and moreover the number of FS phases, increases in SD. SD does not radically modify the organization of afternoon sleep; if some changes (SEMs, FS) are similar to those found in night sleep in SD, others are quite the opposite (latency of the onset of sleep). So SD seems to determine rather steadfast modifications (SEM, sleep onset), but does not affect deeply the way in which other factors, such as metabolic and psychological factors, may interfere with the levels of vigilance.