Neighborhood Greenspace, Extreme Heat Exposure, and Sleep Quality over Time among a Nationally Representative Sample of American Children.

Children's sleep is essential for healthy development, yet over a third of children in the United States experience inadequate sleep. Environmental factors can influence sleep: greenspace exposure can promote better sleep, while heat exposure can disrupt sleep. As global climate change raises nighttime and daytime temperatures, greenspace may mitigate the negative effects of heat stress on sleep. We examined the direct effects of neighborhood greenspace and extreme heat exposure on sleep and the statistical interaction between greenspace and heat exposure on sleep outcomes among a nationally representative, four-year longitudinal sample of 8580 U.S. children ages 9-10 years at baseline. Hierarchical linear models incorporated a neighborhood greenspace measure: percent open park space within individual child census tracts, a measure of extreme neighborhood heat exposure during the summer months, and extensive individual and neighborhood-level covariates to test main and interaction effects on child sleep quality. Neighborhood open park space was related to better sleep quality, after controlling for covariates. Additionally, neighborhood extreme heat exposure was associated with worse sleep quality. A two-way interaction was found between neighborhood open park space and neighborhood heat exposure on sleep quality, suggesting open park space mitigated the negative effects of heat on sleep. The results indicate the potential contribution of open greenspace to improve child sleep and enhance resilience to extreme heat, which is an adverse outcome of climate change.