Abstract
BACKGROUND: Ambient nitrogen dioxide (NO(2)) has been linked to sleep disturbances in adults, yet its impact on pediatric populations remains understudied. METHODS: A total of 112,471 children aged 3-7 years from the Chinese National Cohort of Motor Development were enrolled. Sleep quality was assessed using the Children's Sleep Habits Questionnaire (CSHQ), while NO(2) exposure at home addresses was estimated through a satellite-based spatiotemporal model. Linear mixed-effect models and generalized estimating equations were employed to quantify the associations of NO(2) exposure with CSHQ scores and sleep disturbances, with the adjustment for demographics, meteorological parameters. FINDINGS: Early-life NO(2) exposure was associated with higher CSHQ scores and increased risk of sleep disturbances. Per 10 μg/m(3) increase in NO(2) exposure during 0-3 years and the entire pregnancy was associated with 0.23 (95% confidence interval [CI]: 0.12-0.33) and 0.18 (95% CI: 0.09-0.27) increases in CSHQ score, respectively, indicating poorer sleep quality. A 10 μg/m(3) increase in NO(2) exposure from ages 0-3 years and during the pregnancy was associated with a 1.1% (relative risk [RR] = 1.011, 95% CI: 1.004-1.018) and 1.0% (RR = 1.010, 95% CI: 1.004-1.016) higher risk of sleep disturbances, respectively. Higher NO(2) exposure was linked to greater likelihood of sleep onset delay, sleep-disordered breathing, and daytime sleepiness. The association appeared more pronounced among children exclusively breastfed <6 months (RR = 1.018, 95% CI: 1.001-1.034) compared with those breastfed ≥6 months (RR = 1.009, 95% CI: 1.001-1.018). INTERPRETATION: Early-life exposure to NO(2) is associated with poorer sleep quality in preschool-aged children, highlighting the importance of mitigating air pollution exposure during critical developmental periods to support healthy sleep and child development. FUNDING: Ministry of Science and Technology of the People's Republic of China, National Natural Science Foundation of China, and Shanghai Municipal Health Commission.