American journal of industrial medicine
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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. ⋯ 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.