External exposome and sleep outcomes in the Nurses’ Health Study

BACKGROUND AND AIM: Multiple environmental exposures, including greenness, light-at-night, and air pollution, have been associated with sleep. However, these associations have not been investigated using large longitudinal cohorts with repeated measures. We examined the association between multiple environmental exposures and sleep duration and quality in the Nurses’ Health Study (NHS). METHODS: Between 2000 and 2014, 81,202 NHS participants self-reported sleep duration on biennial questionnaires, and in 2000, 81,294 NHS participants self-reported sleep quality. We estimated annual average greenness using Landsat Normalized Difference Vegetation Index (NDVI) in 270m buffers, annual average light-at-night (LAN) from the U.S. Defense Meteorological Satellite Program’s Operational Linescan System, and predicted PM2.5 from validated nationwide spatiotemporal models at each residential address. Due to evidence of non-linearity, we modeled exposures in quintiles. Sleep duration was dichotomized (≥7 hours; <7 hours) and modeled with generalized estimating equations. Sleep quality was dichotomized (difficulty sleeping none/a little/some of the time; difficulty sleeping a good bit of/all the time) and modeled using logistic regression. We estimated odds ratios (OR) of adverse sleep outcomes comparing the highest and lowest quintile and 95% confidence intervals (CI) for each exposure. We adjusted for individual-level risk factors and included all exposures simultaneously for mutual adjustment. RESULTS: In mutually-adjusted models, higher annual average residential greenness exposure was associated with suggestive lower odds of short sleep duration (OR: 0.97 95% CI: 0.94, 1.00) with similar associations for poor sleep quality (OR: 0.97; 95% CI: 0.90, 1.00). Higher exposure to LAN was associated higher odds of with short sleep duration (OR: 1.18 95% CI: 1.14, 1.23) and poorer sleep quality (OR: 1.12; 95% CI: 1.03, 1.22). Higher exposure to PM2.5 was not associated with sleep outcomes. CONCLUSION: In the NHS cohort, lower residential greenness and higher LAN exposures were associated with lower self-reported sleep duration and quality.