Effects of daytime noise load on the sleep-wake cycle and endocrine patterns in man: I. 24 hours neurophysiological data.

This study examines the influence of daytime noise load on the spontaneous EEG activity during wakefulness and sleep. Twelve healthy male subjects participated in two experimental series, each consisting of three consecutive nights and the two days in between. EEG, EOG, EMG, ECG and respiration were continuously recorded. During one series from 9:00 to 21:00 h the subjects were exposed to 85 dB(A) industrial noise. Direct effects of the noise exposure were a slight blockade of the alpha and theta activity; towards the evening, when self-estimated tiredness was high, increased alpha and beta power were found (p less than .01). Aftereffects on subsequent undisturbed night sleep were a reduction in REM sleep (p less than .001), shortened sleep cycles (p less than .01) and an increase in slow wave sleep during the 2nd sleep cycle (p less than .05). These results are interpreted as signs of strained wakefulness and intensified fatigue, as disturbance of sleep processes and as an intensified need for recovery.