A Six-Year Longitudinal Cohort Study Assessing the Association Between Social Interaction Trajectories and Sleep Health in Older Adults.

Sleep disturbances, including sleep deprivation and non-restorative sleep, pose a severe public health burden for aging populations. While social isolation is a recognized risk factor, rigorous longitudinal studies evaluating the prospective association between dynamic changes in social interaction and subsequent sleep health are lacking. This study details a 6-year longitudinal cohort study involving 473 community-dwelling older adults in Japan who exhibited normal baseline sleep. Social interactions were systematically evaluated using the standardized 18-item Index of Social Interaction. Participants were tracked from 2017 to 2023 to categorize their social trajectories into distinct subgroups, such as persistently high, declining, improving, or persistently low. Sleep duration and restoration were concurrently assessed using national health guidelines. Multivariable logistic regression models were constructed to evaluate the longitudinal relationship of these social trajectories with sleep outcomes, adjusting for baseline demographic, physical, and lifestyle covariates. The study observed that individuals experiencing a longitudinal decline in social interaction, or those remaining persistently isolated, faced a more than two-fold increased risk of developing sleep deprivation and non-restorative sleep compared to those maintaining robust social networks. Conversely, an incremental increase in continuous social interaction scores was significantly associated with a reduced risk of adverse sleep outcomes. These longitudinal findings offer observational evidence regarding the psychosocial determinants of sleep. Integrating standardized social interaction metrics into routine community health surveillance may facilitate early, targeted interventions to support sleep health and promote healthy aging.