Nighttime road traffic noise exposure at the least and most exposed façades and sleep medication prescription redemption - a Danish cohort study

STUDY OBJECTIVES: Traffic noise has been associated with poor sleep quality and short sleep duration. This study investigates the association between nighttime road traffic noise at the least and most exposed façades of the residence and redemption of sleep medication.

METHODS: In a cohort of 44,438 Danes, aged 50-64 at baseline (1993-1997), we identified all addresses from 1987 to 2015 from a national registry and calculated nighttime road traffic noise at the most and least exposed façades. Using Cox Proportional Hazard Models we investigated the association between residential traffic noise over 1, 5, and 10 years before redemption of the first sleep medication prescription in the Danish National Prescription Registry. During a median follow-up time of 18.5 years, 13,114 persons redeemed a prescription.

RESULTS: We found that 10-year average nighttime exposure to road traffic noise at the most exposed façade was associated with a hazard ratio (HR) of 1.05, 95% confidence interval (CI) (1.00 to 1.10) for Ln greater than 55 as compared to not more than 45 dB, which when stratified by sex was confined to men (HR 1.16, 95% CI 1.08 to 1.25). For the least exposed façade the HR for Ln >45 vs ≤35 dB was 1.00, 95% CI (0.95 to 1.05). For the most exposed façade, the overall association was strongest in smokers and physically inactive.

CONCLUSIONS: Long-term residential nighttime noise exposure at the most exposed façade may be associated with a higher likelihood of redeeming prescriptions for sleep medication, especially among men, smokers, and physically inactive.