The impact of insufficient sleep on subjective cognitive dysfunction: Exploring the moderating role of environmental factors at the census tract level

Subjective cognitive decline (SCD) affects approximately 50 % of adults in the United States. Insufficient sleep (< 7 h per night) and environmental hazards (e.g., exposure to traffic, hazardous chemicals, and air pollution) have each been identified as independent risk factors for cognitive dysfunction. Furthermore, sleep duration and environmental hazards may interact to exacerbate cognitive dysfunction. However, this has yet to be tested empirically using nationally representative data. Using the CDC PLACES and EPA EJScreen datasets, we examined the associations between insufficient sleep, environmental hazards (particulate matter < 2.5 micrometers [PM_2.5], Superfund site proximity, traffic volume/proximity), and cognitive dysfunction across 58,014 U.S. Census tracts. Multiple regression analyses revealed that insufficient sleep and more environmental hazard exposure (i.e., higher levels of PM_2.5, and higher volume/closer proximity to traffic) were each significantly associated with an increased prevalence of cognitive dysfunction. Significant interactions also were observed between insufficient sleep and environmental hazards: In Census tracts with higher exposure to PM_2.5, closer proximity/higher volume of traffic, and farther proximity from a Superfund site there was a stronger association between insufficient sleep and cognitive dysfunction. These findings underscore the importance of addressing multiple environmental and behavioral risk factors in efforts to mitigate cognitive dysfunction. The synergistic effects observed highlight the need for integrated interventions that target both sleep health and environmental exposures to improve cognitive health outcomes and promote health equity, especially in underserved populations.