Effects of traffic noise on sleep: a review.

Examination of the effect of noise on sleep indicated the following: 1) Views differ on habituation to noise. 2) REM sleep in all-night sleep decreases with exposure to noise. The probability of transient changes of REM sleep to other stages is low. REM sleep induction may be disturbed by noise exposure, but once it has been induced, changes to other stages or waking occur only to a small extent. 3) A transient decrease in sleep spindles is caused by noise exposure, but the number of sleep spindles for all-night sleep increases. Sleep disturbance by noise is compensated for by an increase in sleep spindles during periods of silence, possibly indicating sleep maintenance. 4) Under certain circumstances, subjective sleep is a better indicator of the effects of noise on sleep than objective sleep parameters determined by sleep polygraphy. 5) There is a linear dose-response relationship between the peak noise level and the rate of stage shift or waking. The threshold of the noise effect is about 40 dBA.