Polybrominated diphenyl ethers (PBDEs) are endocrine disrupting flame retardants that persist in household environments and may affect child development. We examined whether prenatal exposure to BDE-47, one of the most prevalent PBDE congeners, was associated with sleep duration at age 3 years in the Health Outcomes and Measures of the Environment (HOME) Study, a longitudinal birth cohort in Cincinnati, Ohio. Among 231 children with complete exposure and outcome data, multivariable linear regression models adjusting for perinatal and sociodemographic covariates showed no overall association between log₁₀ transformed maternal serum BDE-47 concentrations and sleep duration. However, stratified analyses by household income revealed divergent trends: higher BDE-47 exposure was associated with shorter sleep in lower income households, whereas estimates in higher income households suggested the opposite direction but were not statistically significant. These findings underscore the potential modifying role of socioeconomic context in children’s vulnerability to environmental toxicants.