Single and combined effects of air, road, and rail traffic noise on sleep and recuperation

Abstract

Study objective: Traffic noise disturbs sleep and may impair recuperation. There is limited information on single and combined effects of air, road, and rail traffic noise on sleep and recuperation.

Design: Repeated measures.

Setting: Polysomnographic laboratory study.

Participants: 72 healthy subjects, mean ± standard deviation 40 ± 13 years, range 18-71 years, 32 male.

Interventions: Exposure to 40, 80, or 120 rail, road, and/or air traffic noise events.

Measurement and results: Subjects were investigated for 11 consecutive nights, which included 8 noise exposure nights and one noise-free control night. Noise effects on sleep structure and continuity were subtle, even in nights with combined exposure, most likely because of habituation and an increase in arousal thresholds both within and across nights. However, cardiac arousals did not habituate across nights. Noise exposure significantly affected subjective assessments of sleep quality and recuperation, whereas objective performance was unaffected, except for a small increase in mean PVT reaction time (+4 ms, adjusted P < 0.05). Road traffic noise led to the strongest changes in sleep structure and continuity, whereas subjective assessments of sleep were worse after nights with air and rail traffic noise exposure. In contrast to daytime annoyance, cortical arousal probabilities and cardiac responses were significantly lower for air than for road and rail traffic noise (all P < 0.0001). These differences were explained by sound pressure level rise time and high frequency (> 3 kHz) noise event components.

Conclusions: Road, rail, and air traffic noise differentially affect objective and subjective assessments of sleep. Differences in the degree of noise-induced sleep fragmentation between traffic modes were explained by the specific spectral and temporal composition of noise events, indicating potential targets for active and passive noise control. Field studies are needed to validate our findings in a setting with higher ecologic validity.

Keywords: Aircraft noise; arousal; awakening; health; heart rate; memory; railway noise; reaction time; road traffic noise; traffic noise.

Figure 1

Probability of awakenings (A) and arousals (B) in noise exposure nights in excess of spontaneous probability observed in noise-free control nights is shown. The change in heart rate between periods with and without noise exposure is shown in (C) depending on maximum SPL and traffic mode. Estimates for (A), (B), and (C) were derived from random subject effect regression models and include 95% confidence intervals. *bpm, beats per minute.

Figure 2

The average number of awakenings (A) and arousals (B) is shown for control, single, double, and triple exposure nights. In the exposure nights, spontaneous reactions, reactions under the influence of noise exposure replacing spontaneous reactions, and reactions under the influence of noise exposure additional to spontaneous reactions are differentiated. The horizontal line represents the average number of awakenings/arousals in noise-free control nights.