A critical load for nocturnal high-density road traffic noise.
Eighteen female and 18 male students (21-30 years) slept in the lab during 12 consecutive nights each, where a high-density road traffic noise was played back with four intensities. EEG and EOG were recorded continuously throughout the nights. In the morning the subjects assessed their sleep and completed a reaction time test. The following conclusions were made: Performance was not affected by noise. REM sleep decreased abruptly as soon as the sound pressure level exceeded 44 dBA. With increasing noise, sleep was assessed as increasingly worse. Noise-induced sleep disturbances were not related to sex. The equivalent sound pressure level measured for high-density road traffic seems to be a valuable predictor for subjective sleep disturbances as long as the maximum levels do not exceed it by more than 8-10 dBA. On the basis of the assessment of sleep and supported by the abrupt decrease of REM sleep, an equivalent noise level of 40 dBA indoors was defined as a critical load, above which nocturnal noise cannot be tolerated any longer.
D000328:Adult; D005260:Female; D006185:Habituation, Psychophysiologic; D006801:Humans; D008297:Male; D009622:Noise; D011597:Psychomotor Performance; D012890:Sleep / Q000502:physiology*; D014186:Transportation