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Importance of social relationships in the association between sleep duration and cognitive function: data from community-dwelling older Singaporeans

ABSTRACT Background: Aging is accompanied by cognitive decline that is escalated in older adults reporting extreme sleep duration. Social relationships can influence health outcomes and thus may qualify the association between sleep duration and cognitive function. The present study examines the moderating effects of marital status, household size, and social network with friends and relatives on the sleep–cognition association among older adults. Methods: Data (N = 4,169) came from the Social Isolation, Health, and Lifestyles Survey, a nationally representative survey of community-dwelling older Singaporeans (≥ 60 years). Sleep duration and social relationships were self-reported. Cognitive function was assessed with the Short Portable Mental Status Questionnaire. Results: Regression analysis revealed that the inverted U-shaped association between sleep duration and cognitive function was less profound among older adults who were married (vs. unmarried) and those who had stronger (vs. weaker) social networks. In contrast, it was more prominent among individuals who had more (vs. fewer) household members. Conclusions: Being married and having stronger social networks may buffer against the negative cognitive impact of extreme sleep duration. But larger household size might imply more stress for older persons, and therefore strengthen the sleep duration–cognitive function association. We discuss the potential biological underpinnings and the policy implications of the findings. Although our findings are based on a large sample, replication studies using objective measures of sleep duration and other cognitive measures are needed.