Early-Life Exposure to PM 2.5 and Sleep Disturbances in Preschoolers from 551 Cities of China

Air pollution has been linked with sleep disturbance in adults, but the association in children remains unclear. To examine the associations of prenatal and postnatal exposure to fine particulate matter (particulate matter ⩽2.5 μm in aerodynamic diameter; PM ) with sleep quality and sleep disturbances among children in 551 Chinese cities. A total of 1,15,023 children aged 3-7 years from the Chinese National Cohort of Motor Development were included. Sleep quality was measured using the Children's Sleep Habits Questionnaire (CSHQ). PM exposure was estimated using a satellite-based model. Generalized additive mixed models with Gaussian and binomial distributions were used to examine the associations of PM exposure with CSHQ scores and risk of sleep disturbance, respectively, adjusting for demographic characteristics and temporal trends. Early-life PM exposure was associated with higher total CSHQ score, and the association was stronger for exposure at age 0-3 years (change of CSHQ score per interquartile range increase of PM = 0.46; 95% confidence interval [CI], 0.29-0.63) than during pregnancy (0.22; 95% CI, 0.12-0.32). The associations were more evident in sleep-disordered breathing and daytime sleepiness. Postnatal PM exposure was associated with increased risk of sleep disturbance (adjusted odds ratio for per-interquartile range increase of PM exposure at age 0-3 years, 1.10; 95% CI, 1.04-1.15), but no associations were found for prenatal exposure. Children who were exclusively breastfed for