Associations of long-term exposure to ambient air pollution and physical activity with insomnia in Chinese adults.

Abstract Background Air pollution is a potential environmental risk for sleep disturbance. However, the evidence is very limited in China. On the other hand, physical activity (PA) is a preventive behavior that can improve insomnia, but whether PA mitigates the negative impact of air pollution on insomnia is unknown. Methods We obtained data from the baseline of China Multi-Ethnic Cohort (CMEC) survey, and examined the association between air pollution and insomnia, as well as PA's modification effect of on this association. We included 70,668 respondents and assessed insomnia by self-reported symptoms collected using electronic questionnaires. Using satellite data, we estimated the residence-specified, three-year average PM1, PM2.5, PM10 (particulate matter with aerodynamic diameters of ≤1 μm, ≤2.5 μm and 10 μm, respectively), O3 (ozone), and NO2 (nitrogen dioxide) concentrations. We established the associations between air pollutants and insomnia through logistic regression. We evaluated the modification impact of total and domain-specific PA (leisure, occupation, housework, transportation) by introducing an interaction term. Results Positive associations were observed between long-term exposure to PM1, PM2.5, PM10, and O3 and insomnia symptoms, with ORs (95% CI) of 1.09 (1.03–1.16), 1.11 (1.07–1.15), 1.07 (1.05–1.10) and 1.15 (1.11–1.20), respectively. As total PA increased, the ORs of air pollution for insomnia tended to decrease and then rise. We observed varying modification effects of domain-specific PA. With an increase in leisure PA, the ORs for PM2.5 and PM10 significantly declined. However, increased ORs of air pollutants were related to insomnia among participants with higher levels of occupational and housework PA. Conclusion Long-term exposure to higher concentrations of PM1, PM2.5, PM10, and O3 increases the risk of insomnia symptoms. Moderate to high levels of leisure PA alleviate the harmful effects of air pollution on insomnia, while high levels of occupation and housework PA intensify such effects.