Road traffic noise impacts sleep continuity in suburban residents: Exposure-response quantification of noise-induced awakenings from vehicle pass-bys at night.

Nocturnal traffic noise has been associated with adverse health outcomes in exposed residents. Precise quantification of traffic noise effects on sleep is thus of great importance. Here we establish an exposure-response relationship for the awakening probability due to intermittent road traffic noise in suburban residents. We conducted a field study in residential areas where road traffic was the dominant noise source, and noise events were attributable to separate vehicle pass-bys. Forty healthy participants underwent polysomnography for five consecutive nights at their homes. A total of 11,003 road traffic noises derived from simultaneous acoustic measurements at the sleepers' ears were included in an event-related analysis of awakenings. Logistic regression analysis revealed that the awakening probability due to road traffic noise increased with the maximum sound pressure level (SPL) and the maximum slope of the increasing SPL of a vehicle pass-by, as well as the age of the exposed individual. Compared to sleep stage 2, the awakening probability was higher in rapid eye movement sleep (REMS) and lower in slow wave sleep (SWS). The protective effect of both stage 2 and SWS against awakenings decreased with age, whereas no age-dependent change was observed for REMS. When adjusting for other contributing factors, the probability of a noise-induced awakening ranged from 0% at a maximum SPL of 27.1 dB(A) to 2.0% at 70 dB(A). Road traffic noise at night - even in suburban areas with moderate traffic density - negatively impacts residents' sleep continuity. Exposure-response quantification for traffic noise-induced awakenings may serve as a basis for noise protection efforts by regulators and policy makers.