Rest Assured: The Association of Structural, Functional Support, and Loneliness With Subjective Sleep Health.

Sleep is increasingly understood as a socially embedded phenomenon. This study examined how structural and functional aspects of social support, as well as loneliness, relate to sleep health in a German sample of middle-aged adults (N = 5388). Drawing on the socio-ecological model of sleep health, we assessed the contributions of social support dimensions while accounting for age, sex, and socioeconomic status, as well as psychological covariates. The results of the binary logistic regression showed that functional support (ESSI), friend network size (LSNS6), and loneliness (CES-D item 14) significantly (p < 0.001) predicted sleep health (PSQI), while family network size did not. The portion of explained variance was small (4%-5%). Results remained robust after adjusting for age, sex, and socioeconomic status, but no longer when including psychological covariates (GAD-7, SWLS, CES-D), in which case only the friend network size remained significant (p = 0.019). Women were significantly more affected by poor sleep health than men, and with higher socioeconomic status, fewer people reported suffering from poor sleep (all: p < 0.001). Additional subgroup analysis revealed higher age as a risk factor for worse sleep health in women only, while the friend network was only relevant in men. Our findings highlight the importance of distinguishing between structural and functional dimensions of social support in sleep health research and interventions, and suggest a potential sex-by-age interaction. Future research should promote equity by including diverse populations and longitudinally examine how social support, especially friend networks, affects sleep across genders, ages, and contexts.