Abstract MP43: The Role of the Physical Environment in Racial Differences in Sleep Duration

Background: Racial and ethnic sleep disparities have been documented; however, the mechanisms are unclear. The physical environment is associated with sleep duration and may explain sleep disparities. We examined the physical environment as a mediator of racial differences in sleep duration using data from the Multi-Ethnic Study of Atherosclerosis (N=2073). Methods: Participants underwent 1-week actigraphy, completed questionnaires on the neighborhood environment, and addresses were geocoded and linked to physical environment features. Actigraphy-measured sleep duration was analyzed as both continuously and categorically (short sleep duration < 6 hours vs. ≥ 6 hours). Physical environment characteristics included availability of healthy foods, aesthetic quality, walking environment, walking destination density, the proportion of land dedicated to retail space and an overall built environment score. Multi-level linear and Poisson regression models with robust variance were fit to examine associations of race, physical environment, and sleep duration with adjustment for covariates. Direct and indirect mediation was tested via path models. Results: The mean age was 68.6 ± 9.2 years. Approximately 46% of participants were male and 37.7% White, 27.7% Black, 23.1% Hispanic, and 11.5% Chinese American. The prevalence of short sleep (6 hours) was highest for racial minorities, ranging from 32.2% to 44.3% compared to 19.2% for White adults. A higher built environment factor score was associated with shorter sleep duration. The physical environment partially mediated racial disparities in sleep duration between Hispanic and White adults. A significant indirect effect of race on sleep duration via aesthetic quality, walking destination density, proportion retail and the built environment factor score was detected, explaining 4.0%, 27.2%, 7.6%, and 37.8%, respectively of the association between race and sleep duration for Hispanic individuals, compared to White individuals. The physical environment did not explain the Black-White or Chinese-White disparity in sleep duration. Conclusion: Black, Hispanic, and Chinese individuals had shorter sleep duration than White individuals. The Hispanic-White disparity in sleep duration was partially explained by the physical environment. These findings suggest that the physical environment may be an important mechanism in which racial disparities in sleep exist and a likely a target for intervention.