Sex differences in the association between social relationships and insomnia symptoms

Study Objectives: Social relationships are an understudied factor affecting insomnia. In particular, these effects have not been evaluated in the context of sex differences. In this study, we investigated differences between sexes with regard to the association between insomnia symptoms and social relationships. Methods: We used data from 2681 middle-aged adults (aged 40–64 years; females, 68.8%) from the Cardiovascular and Metabolic Diseases Etiology Research Center project. Insomnia symptoms were defined as difficulty with sleep induction or maintenance ≥3 nights per week. We assessed social network size and bridging potentials as indicators of social relationships. Social network size is a quantitative measure of the size of social relationships, and bridging potential is a qualitative indicator of the diversity and independence of these relationships. Multivariate regression analysis controlling for confounding factors was performed to evaluate associations between social relationships and insomnia symptoms. Results: Smaller social network size was significantly associated with sleep induction (adjusted odds ratio = 0.866, P =.015) and sleep maintenance (adjusted odds ratio = 0.862, P =.015) difficulties, but only in men. Poor bridging potential was also associated with sleep induction (adjusted odds ratio = 0.321, P =.024) and maintenance (adjusted odds ratio = 0.305, P = .031) difficulties only in men. For women, social relationship variables were not significantly associated with insomnia symptoms. Conclusions: The association between insomnia symptoms and social relationships varied by sex, as noted by statistical analyses accounting for covariates affecting insomnia symptoms. These results suggest that qualitative assessments of social relationship variables should be considered in clinical practice, since these variables can be interpreted differently for men and women.