Environmental Noise and Effects on Sleep: An Update to the WHO Systematic Review and Meta-Analysis

BACKGROUND: Nighttime noise carries a significant disease burden. The World Health Organization (WHO) recently published guidelines for the regulation of environmental noise based on a review of evidence published up to the year 2015 on the effects of environmental noise on sleep. OBJECTIVES: This systematic review and meta-analysis will update the WHO evidence review on the effects of environmental noise on sleep disturbance to include more recent studies. METHODS: Investigations of self-reported sleep among residents exposed to environmental traffic noise at home were identified using Scopus, PubMed, Embase, and PsycINFO. Awakenings, falling asleep, and sleep disturbance were the three outcomes included. Extracted data were used to derive exposure–response relationships for the probability of being highly sleep disturbed by nighttime noise [average outdoor A-weighted noise level ([Formula: see text]) 2300–0700 hours] for aircraft, road, and rail traffic noise, individually. The overall quality of evidence was assessed using Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) criteria. RESULTS: Eleven studies ([Formula: see text] responses) were included in addition to 25 studies ([Formula: see text] responses) from the original WHO analysis. When sleep disturbance questions specifically mentioned noise as the source of disturbance, there was moderate quality of evidence for the probability of being highly sleep disturbed per 10-dB increase in [Formula: see text] for aircraft [[Formula: see text]; 95% confidence interval (CI): 2.01, 2.36], road ([Formula: see text]; 95% CI: 2.28, 2.79), and railway ([Formula: see text]; 95% CI: 2.57, 3.43) noise. When noise was not mentioned, there was low to very low quality of evidence for being sleep disturbed per 10-dB increase in [Formula: see text] for aircraft ([Formula: see text]; 95% CI: 1.20, 1.93), road ([Formula: see text]; 95% CI: 1.08, 1.21), and railway ([Formula: see text]; 95% CI: 0.91, 1.49) noise. Compared with the original WHO review, the exposure–response relationships closely agreed at low (40 dB [Formula: see text]) levels for all traffic types but indicated greater disturbance by aircraft traffic at high noise levels. Sleep disturbance was not significantly different between European and non-European studies. DISCUSSION: Available evidence suggests that transportation noise is negatively associated with self-reported sleep. Sleep disturbance in this updated meta-analysis was comparable to the original WHO review at low nighttime noise levels. These low levels correspond to the recent WHO noise limit recommendations for nighttime noise, and so these findings do not suggest these WHO recommendations need revisiting. Deviations from the WHO review in this updated analysis suggest that populations exposed to high levels of aircraft noise may be at greater risk of sleep disturbance than determined previously. https://doi.org/10.1289/EHP10197