Association of long-term exposure to ambient air pollutants with prolonged sleep latency: The Henan Rural Cohort Study

Background: Prolonged sleep latency is associated with far-reaching public health consequences. Although evidence about the effect of air pollution on sleep problem has been shown, the effect on sleep latency remained unknown. The study aimed to analyze the association between long-term exposure to air pollution and prolonged sleep latency in rural China. Methods: In all, 27935 participants were included in the study from Henan Rural Cohort Study. A satellite-based spatiotemporal model was used to evaluate the 3-year average concentration of air pollutants at the home address of participants before the baseline survey. Air pollutants included NO₂ (nitrogen dioxide), PM₁ (particulate matter with aerodynamic diameters ≤1 μm), PM_2.5 (particulate matter with aerodynamic diameters ≤ 2.5 μm), and PM₁₀ (particulate matter with aerodynamic diametes ≤ 10 μm). A logistic regression model was conducted to assess the odds ratio (OR) and 95% confidence interval (95% CI) between air pollutants and prolonged sleep latency. Results: There were 5825 (20.85%) participants with prolonged sleep latency. The average concentration of NO₂, PM₁, PM_2.5, and PM₁₀ were 38.22 (2.54) μg/m³, 56.29 (1.75) μg/m³, 72.30 (1.87) μg/m³, and 130.01 (4.58) μg/m³. The odds ratio (95%CI) of prolonged sleep latency with an IQR increase of NO₂, PM₁, PM_2.5, and PM₁₀ were 1.59 (1.33–1.90), 1.23 (1.13–1.33), 1.28 (1.13–1.45) and 1.43 (1.22–1.67). The stratified analysis showed the effect of air pollutants was stronger among those with stroke. Conclusion: Long-term exposure to NO₂, PM₁, PM_2.5 and PM₁₀ were associated with prolonged sleep latency. The adverse impact of air pollution should be considered when treating sleep problems.