Does social support differentially affect sleep in older adults with versus without insomnia?

Abstract

Objective

Insomnia is a significant public health problem, particularly among older adults. We examined social support as a potential protective factor for sleep among older adults (60 years and older) with insomnia (n=79) and age- and sex-matched controls without insomnia (n=40).

Methods

Perceived social support, sleep quality, daytime sleepiness, and napping behavior were assessed via questionnaires or daily diaries. In addition, wrist actigraphy provided a behavioral measure of sleep continuity parameters, including sleep latency (SL), wakefulness after sleep onset (WASO), and total sleep time (TST). Analysis of covariance for continuous outcomes or ordinal logistic regression for categorical outcomes were used to examine the relationship between social support and sleep-wake characteristics and the degree to which observed relationships differed among older adults with insomnia versus non-insomnia controls. Covariates included demographic characteristics, depressive symptoms, and the number of medical comorbidities.

Results

The insomnia group had poorer subjective sleep quality, longer diary-assessed SL and shorter TST as compared to the control group. Higher social support was associated with lesser actigraphy-assessed WASO in both individuals with insomnia and controls. There was a significant patient group by social support interaction for diary-assessed SL, such that higher levels of social support were most associated with shorter sleep latencies in those with insomnia. There were no significant main effects of social support or social support by patient group interactions for subjective sleep quality, daytime sleepiness, napping behavior, or TST (diary or actigraphy assessed).

Conclusion

These findings extend the literature documenting the health benefits of social support, and suggest that social support may similarly influence sleep in individuals with insomnia as well as non-insomnia controls.

Introduction

Insomnia is a highly prevalent and debilitating sleep disorder that disproportionately affects older adults [1], [2]. However, some studies have suggested that age per se, is not a risk factor for insomnia but rather, age-related declines in mental and physical health are responsible for the excess risk [3]. Ohayon et al. [3] have further shown that social factors, including social isolation or dissatisfaction with social activities may further contribute to age-related increases in insomnia risk. Conversely, high levels of social support may be an important, though under-investigated, protective factor associated with healthier sleep, particularly among vulnerable populations, such as older adults. Indeed, evidence from the broader social support literature documents particularly robust effects of social support on health outcomes in older populations [4], [5].

There are a number of reasons to predict that social support should be beneficial for sleep. First, social support could influence sleep by providing a sense of belonging and connectedness, inducing positive mood states, and promoting positive health behaviors, including maintaining healthy sleep habits [6]. Moreover, perceiving that others “are there” and “will be there” for the individual protects against social isolation and loneliness, factors that have previously been associated with increased risk of sleep disturbance [7], [8], [9]. In addition, social supports may operate as social zeitgebers (i.e., “time-givers”) which facilitate entrainment of circadian rhythms [10], [11], thereby helping to maintain a more consistent and consolidated sleep-wake schedule. For example, regularly meeting a friend for breakfast may benefit sleep not only by promoting a sense of belonging and enhancing well-being and deterring against negative emotions associated with sleep disturbance, but also by reinforcing a consistent sleep and wake routine. Social support could also influence sleep by attenuating the effects of psychological stress on sleep [12], [13], [14]. Finally, there may be tangible aspects of social support that may benefit sleep, such as increasing access to material aid or resources, including information about healthy sleep habits. Thus, there are several plausible pathways that may link different types of social support with sleep, including protecting against social isolation, attenuating stress responses, providing a sense of belonging and emotional support, encouraging healthy sleep behaviors, and entraining circadian rhythms.

Indeed, a number of studies have shown that aspects of the social environment are related to sleep disturbances in older adults [7], [15], [16], [17], [18]. However, the bulk of the extant literature has focused on the presence or absence of relationships (e.g., married versus unmarried) rather than the social supportive functions relationships provide. Moreover, among the studies that have examined social support per se, most have relied on single-or few-item measures of social support (e.g., “do you have a confidante?”), which have questionable reliability and validity, and only capture a single dimension of social support (e.g., emotional). Utilizing a more comprehensive and validated assessment of social support may provide a more sensitive examination of the links between social support and sleep.

With few exceptions [7], [19] the extant literature has focused exclusively on the relationship between social support and self-reported sleep disturbances. These findings may reflect a more general negative affect bias, leading to negative perceptions of sleep and of social support. Thus, a more comprehensive test of the association between social support and sleep would be to include both behavioral and self-report measures of sleep. It is also important to examine whether observed associations between social support and sleep persist after statistical adjustment for other factors known to covary with sleep and social factors, including mental and physical health comorbidities. Indeed, given evidence that sleep disturbances may be an important predictor of functioning in older adults, including engagement in social activities [20], it is also plausible that the reverse pathway is true; sleep disturbances may lead to more negative perceptions of the social environment. Although cross-sectional studies cannot determine causality nor the directionality of the relationship, statistical control for variables that may account for the relationship affords the opportunity to examine the degree to which social support and sleep are associated, independent of other known risk factors. Finally, epidemiological studies which have included questions on sleep typically assess a limited number of sleep complaints or symptoms, but do not specifically examine whether results are similarly evidenced in individuals with a clinically significant sleep disorder. Given that insomnia is the most common sleep disorder, particularly among older adults, it is critical to examine whether the association between social support and sleep still holds for individuals with insomnia, or whether the association is evident only in non-sleep-disordered populations. That is, does the sleep disorder itself mask the association between social support and sleep? Previous research on the role of stress in the pathophysiology of insomnia suggests that individuals with insomnia are more vulnerable to stress-related sleep disturbances than normal sleepers [14], findings which may be attributable, at least in part, to a relative deficiency or inability to effectively utilize social support resources.

The present study examined the association between a well-validated and comprehensive measure of social support and sleep as measured by both self-report and by actigraphy, which provides a behavioral measure of rest-activity patterns. Participants in the study included individuals with well-characterized histories of insomnia and non-insomnia controls who were comparable in terms of age and sex. First, we examined whether perceptions of social support differed between individuals with insomnia and controls. Given the high comorbidity between insomnia and mood disorders, most notably, depression [2], [21], and that perceptions of social support may reflect, at least in part, a general affective bias [22], we predicted that individuals with insomnia would perceive lower levels of social support than controls. Second, we examined whether higher levels of social support are uniquely related to sleep outcomes, or whether social support is merely a proxy for depressive symptoms, general health, or demographic characteristics (including the presence or absence of a spouse) that are related to sleep. We hypothesized that higher levels of social support would be independently associated with better sleep, even after statistically controlling for relevant covariates. Finally, we examined whether the association between social support and sleep differed among individuals with insomnia and good sleeper controls. We predicted that the association between social support and sleep would be stronger among non-insomnia controls than among individuals with insomnia. That is, consistent with prior research showing greater susceptibility to stress-related sleep disturbances among individuals with insomnia, we predicted that individuals with insomnia would also fail to reap the benefits of social support as compared to controls.