Social Integration and Sleep Disturbance: A Gene-Environment Interaction Study

David A Sbarra

doi:10.1525/collabra.29

Abstract

Objective: Low levels of perceived social integration, or loneliness, are associated with increased risk for a range of poor health outcomes. Sleep disturbance plays a central role in the evolutionary theory of loneliness, which provides a mechanistic account of how low levels of social integration may negatively impact health. No studies, however, have examined whether the association between social integration and sleep disturbance is consistent with a causal effect after accounting for genes that are common to both variables.Method: Using twin data (N = 905 twin pairs) from the nationally-representative Midlife in the United States (MIDUS) survey, I evaluated a series of bivariate twin models exploring whether the phenotypic association between low social integration and sleep disturbance can be explained by shared genetics. In addition, the current study specified a series of quantitative models for studying gene x environment (G X E) interactions to determine whether the genetic and environmental influences on sleep disturbance differ as a function of social integration.Results: The phenotypic association between social integration and sleep disturbance was fully accounted for by genes that are common between the two variables, suggesting that within-twin pair differences in social integration do not exert a causal influence on sleep disturbance. Social integration, however, moderated the non-shared environmental influence on sleep disturbances, with the greatest environmental influences observed at the lowest levels of social integration.Conclusions: The results of this study suggest that an essential feature of the evolutionary model of loneliness may need refinement or elaboration. The moderation findings are discussed in terms of the fit with a stress-buffering model of social support in which environmental influences on sleep disturbance are strongest when social resources are low.

Highlights

The main goal of this paper is to investigate whether within-pair differences in social integration are associated with sleep disturbances once genetic influences that are common to both variables are taken into account
Evidence from the Midlife in the United States (MIDUS) sample suggests that common genetics cannot be excluded from the model; the negative phenotypic association between perceived social integration and perceived sleep disturbance is best explained by genes that are common to both variables
Sleep and sleep disturbances play an important role in the evolutionary theory of loneliness [13], but is loneliness a causal agent of ill health or a marker of risk more generally? The theory dictates that the lonely are hypervigilant about their social standing; this hypervigilance can extend to sleep difficulties, and these difficulties represent an important route through which loneliness may affect health

Summary

Methods

Participants contributing to the current analyses were part of the Midlife in the United States (MIDUS) survey twin sample. As reported in detail elsewhere (e.g., [24]), zygosity was assessed via self-report using questions about eye and hair color, as well as the degree to which people were confused as to the twin’s identity in childhood. This approach is valid and widely used [27], but 16 of the MIDUS twin pairs were deemed to have indeterminate zygosity and were excluded from the present analysis. The author’s local institutional review board does not consider de-identified secondary data analysis to be human subjects research

Results

Discussion

Conclusion