Objectives: The objective of this study was to test whether light pollution is associated with lower or insufficient sleep. The American Medical Association recently issued a public notice cautioning against the effects of nighttime light on sleep quality and quantity. Light pollution, through the suprachiasmatic nucleus, disrupts circadian rhythm by reducing the secretion of melatonin, a sleep-inducing hormone.
Methods: I used 282 403 individual self-reports of sleep hours and insufficient sleep from the 2014 and 2016 metropolitan and micropolitan statistical area (MMSA) Behavioral Risk Factor Surveillance System (BRFSS) and the prevalence of insufficient sleep during 2014 in 2823 US counties from the County Health Rankings. The nighttime artificial light data are from the cloud-free Visible Infrared Imaging Radiometer Suite available from the National Oceanic and Atmospheric Administration in the US.
Results: At the MMSA level, for a 10-unit increase in nighttime light (nW/[cm2 sr]) the estimated decline in sleep was about 5.59 minutes per day and the odds of reporting insufficient sleep (<7 hours) increased by 13.77%. At the county-level, for a 10-unit increase in nighttime light, the prevalence of insufficient sleep increased by 2.19%.
Conclusions: Although light pollution was negatively associated with sleep outcomes, the practical effect sizes were small. The small effects suggest that the effects at the population level are negligible, and the effect of nighttime light pollution is more idiosyncratic.
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