Objective: A growing number of studies have associated various measures of social integration, the diversity of social roles in which one participates, with alterations in hypothalamic-pituitary-adrenocortical (HPA) functioning. The pathways through which social integration may be linked to HPA functioning, however, are as yet unknown. The present study examined whether daily social interactions, affective responses, health behaviors, and personality help explain the association between social integration and diurnal cortisol slope.
Methods: A sample of 456 healthy, employed adults (53.9% female, 82.0% white, 72.2% bachelor's degree or greater, mean age of 42.86 years) completed a 4-day ecological momentary assessment protocol that measured cortisol, social interactions, affect, sleep, and physical activity at frequent intervals throughout the day. Social integration was measured at baseline.
Results: Regression results controlling for age, sex, race, and education indicated that more socially integrated individuals showed steeper cortisol slopes (B = -0.00253, p = .006). Exploratory analyses suggested that the consistency (i.e., reduced variability) in nightly sleep midpoint partially explained this association (B = -0.00042, 95% confidence interval = -0.00095 to -0.00001). Personality, mood, social interaction patterns, and nonsleep health behavior differences did not account for the association between social integration and HPA activity.
Conclusion: This study replicates previous findings linking social integration and HPA functioning, and it examines patterns of nightly sleep as possible pathways through which the association may operate. Results have implications for understanding mechanisms for health risk and for development of future interventions.