Transportation noise, sleep, and possible after-effects

Laboratory and field research indicate that intermittent noise is more disturbing to sleep than continuous noise. The effect increases with maximum sound pressure level of individual noise events and the ratio of this level to background noise level. The rate of increase of probability of arousal or awakening as a function of noise level is much less than that for sleep stage change. Intermittent traffic noise may decrease time spent overnight in slow-wave sleep (SWS), and increases its onset latency, especially in younger persons. Field studies indicate that this effect may not habituate, suggesting that large numbers of young adults in cities may be chronically SWS-deprived to some degree. Laboratory data indicate that habituation of arousal responses to noise events may occur without reducing the effects on task performance the next day. Chronic exposure to traffic noise during sleep may affect mood states. Minor effects on heart rate occur even after many years of nightly exposure to noise. Short-term increases in sympathetic nervous tone occur in laboratory sleep due to single noise events. Further research is suggested, into psychological factors modifying the effects of noise on sleep, and possible associations between noise-disturbed sleep and immune response, and child development.