Beyond single sleep measures: A composite measure of sleep health and its associations with psychological and physical well-being in adulthood

https://doi.org/10.1016/j.socscimed.2021.113800Get rights and content

Highlights

  • Sleep health composite relates to perceived stress and chronic conditions.

  • Sleep health composite is associated with chronic conditions nine years later.

  • Adults with fewer conditions but more sleep problems increase chronic conditions.

  • Sleep health composite explains extra variance in adult well-being.

  • Sleep satisfaction/quality is most strongly associated with adult well-being.

Abstract

Rationale. Sleep is important for many functions including body and mind restoration. Studies report the association of sleep with stress and physical deterioration, often focusing only on sleep duration; yet, sleep health needs to be understood by multiple dimensions to comprehensively capture its impact on well-being.

Objective. This study examined cross-sectional and longitudinal associations of multidimensional sleep health with perceived stress and chronic physical conditions.

Methods. We used a sample of 441 adults (M age = 57 years) who participated in the biomarker project of the Midlife in the United States Study. Participants provided self-report and actigraphy sleep data in 2004–2009 (T1). We created a composite score of sleep health (Range = 0–6; higher indicating more sleep problems) encompassing: actigraphy-measured regularity, timing, efficiency, duration, and self-reported satisfaction and alertness. Participants responded to the perceived stress scale and chronic physical conditions checklist at T1; chronic physical conditions were reassessed in 2013–2015 (T2).

Results. Cross-sectionally, a composite score of sleep health problems was uniquely associated with higher perceived stress and more chronic conditions, explaining additional variance that each individual sleep variable did not explain. Sleep duration – one of the most commonly researched dimensions of sleep – was not associated with either perceived stress or chronic conditions. Longitudinally, for individuals who had fewer chronic conditions at T1, having more sleep health problems was associated with an increase in chronic conditions at T2. Among the multiple dimensions, sleep satisfaction was most consistently and strongly associated with the outcomes.

Conclusion. Findings suggest the importance of considering multiple sleep dimensions concerning psychological and physical well-being in adulthood.

Introduction

Sleep plays a critical role in maintaining optimal functions of mind and body, such as recovering from psychological stress and restoration of physical energy (Haroz et al., 2017; Krueger et al., 2016). Prior literature has shown that insufficient or extended sleep duration and poor sleep quality are associated with a variety of adverse well-being and health outcomes, including perceiving more daily stressors (Lee et al., 2017; Sin et al., 2017), elevated risk of inflammation in those with arthritis (Lee et al., 2019a, 2019b, 2019c), incidence of falls (Chen et al., 2017), and pain (Chen et al., 2019; Finan et al., 2013). However, the literature is limited in that many studies have focused on single dimensions of sleep. According to a sleep health perspective, sleep health is not just the absence of a sleep disorder and needs to be understood by multiple dimensions (Buysse, 2014). We take this perspective to examine unique properties of a composite measure of multidimensional sleep health in relation to perceived stress and chronic physical conditions, two important adult well-being outcomes found to be significantly associated with single sleep variables in prior research.

The sleep health perspective by Buysse (2014) highlights multiple dimensions of sleep and their coordinated changes to optimize overall health and functioning. For example, an individual without a sleep disorder may not be considered as healthy if he/she has an irregular sleep schedule and/or inefficient sleep. The idea is in line with previous models of health, such as the World Health Organization (WHO) model and environmental or adaptive models that emphasize prevention, integrated functioning of body and mind, and adaptation, beyond disease and disability (Julliard et al., 2006; Larson, 1999). The sleep health perspective (Buysse, 2014) suggests six dimensions of sleep critical to psychological and physical well-being: regularity, satisfaction, alertness, timing, efficiency, and duration (RU SATED). Research based on this perspective shows that an aggregate measure of sleep health is associated with prevalent and incident depression symptoms in older women (Furihata et al., 2016), mortality in older men (Wallace et al., 2018a, 2018b) and mental and physical health outcomes in adolescents (Dong et al., 2019). Although specific sleep variables used in these studies differ, they have commonly assessed the six sleep dimensions. In the study by Dong et al. (2019), a composite sleep health score encompassing regularity, satisfaction, alertness, timing, efficiency, and duration is determined based on a 7-day sleep diary and a global survey. They report significant associations of the sleep health composite with multiple health outcomes such that higher sleep health is related to lower depressive and anxiety symptoms, fewer social problems related to friends and family, and lower odds of obesity. Little is known about the effect of composite sleep health on adults, despite that adulthood may involve diverse sleep health issues due to various lifestyle factors and age-related changes. For example, marriage, stress stemming from work and family responsibilities, and natural age-related changes in circadian shift and sleep architecture may cause sleep health issues in adulthood (Buxton et al., 2016; French et al., 2019; Maume et al., 2010; Ohayon et al., 2004).

We focus on perceived stress and the number of chronic physical conditions, two independent outcomes that can broadly assess psychological and physical well-being for an average adult. With regard to sleep—stress relationship, previous studies report univariate associations of single sleep variables with a variety of stress-related outcomes, such as work-family conflict, job strain, and stressful life events. Compared to these measures that are mostly event-specific or subgroup (worker)-specific, perceived stress can capture the degree to which overall situations in one's life are appraised as stressful (Cohen et al., 1983). In relation to physical conditions, most studies have often used specific disease conditions (e.g., diabetes, hypertension, obesity), lacking the assessment of cumulated morbidity associated with sleep issues.

Previous studies show the associations of sleep duration and sleep quality with psychological and physical well-being. Adults with shorter actigraphy-measured sleep duration (Berkman et al., 2015) or self-reported sleep duration (Sekine et al., 2014) report more stress across work and family domains. Poorer self-reported sleep quality in adults is also associated with more stressful life events (Hall et al., 2015) and work-related stressors and job strain (Berset et al., 2011; Karhula et al., 2013; Lee et al., 2019a; Lee et al., 2017). Concerning physical well-being outcomes, self-reported sleep duration has u-shaped relationships with physical and mental health functioning and the risks of diabetes, hypertension, obesity, and cardiovascular disease (Buxton and Marcelli, 2010; Sekine et al., 2014). Studies also report that self-reported sleep deficiency (short sleep duration, sleep insufficiency, and frequent insomnia symptoms) in adults is associated with functional limitations and the risks of angina, arthritis, and depression (Buxton et al., 2012; Koyanagi et al., 2014). Most of these studies are cross-sectional and thus directionality between variables cannot be determined. A systematic review of longitudinal studies, however, shows the effect of short sleep duration on follow-up incidents of diseases such as diabetes mellitus, hypertension, cardiovascular diseases, stroke, coronary heart diseases, obesity, depression, and dyslipidemia (Itani et al., 2017). Across studies, findings are consistent on sleep quality, but not on sleep duration; some studies report a lack of association between the quantity of sleep and adult health outcomes (Sato et al., 2020; Wallace et al., 2018a, 2018b).

Compared to the dimensions of sleep duration and sleep quality, less is known about whether and how regularity, timing, and efficiency of sleep are associated with psychological and physical well-being in adulthood. Limited studies, however, provide some insight. For example, age-appropriate bedtime routines and regularity during childhood are associated with lower body mass index in adolescence (Lee et al., 2019a, 2019b, 2019c). Either too early or too late sleep timing are associated with greater mortality risk in older adults (Wallace et al., 2019; Wallace et al., 2018a, 2018b). Sleep efficiency, which refers to difficulty falling asleep and returning to sleep or lower proportion of sleep in total time in bed, is found to be related to coronary heart disease and early mortality (Dew et al., 2003; Grandner et al., 2012; Nilsson et al., 2001).

The present study had three specific aims. First, we aimed to describe multidimensional sleep health characteristics in U.S. adults. We used six sleep dimensions (RU SATED) critical to overall health and functioning as suggested by the sleep health perspective and previous seminal work (Buysse, 2014; Dong et al., 2019). Sleep dimensions that require subjective evaluation (i.e., satisfaction/quality, alertness/sleepiness) were measured by self-report. Other sleep dimensions that can be objectively assessed (i.e., regularity, timing, and duration) were assessed by actigraphy. Second, we examined cross-sectional associations of a composite measure of sleep health with two important adult well-being outcomes – perceived stress and chronic physical conditions. We hypothesized that more sleep health problems across the six dimensions would be associated with higher perceived stress and more chronic conditions. Lastly, taking advantage of follow-up assessment of chronic physical conditions 9 years later, we examined a longitudinal association between sleep health composite and chronic physical conditions. We tested whether sleep health problems were associated with an increase in the number of chronic conditions over time, independent of age effect. We also explored moderation by baseline chronic conditions, because having more chronic conditions may accelerate the speed of multimorbidity accumulation during aging (Marengoni et al., 2011) and the longitudinal implication of sleep health problems may differ between adults with fewer chronic conditions versus those with multiple comorbid conditions initially.

Section snippets

Participants

Data for the current study were drawn from the Midlife in the United States Survey (MIDUS). Comprehensive details of the design and sample can be found in previous research (Brim et al., 2004). Fig. 1 shows a consort diagram. Out of 1255 individuals who participated in the biomarker project during MIDUS II, 441 individuals participated in the actigraphy sleep study; thus the final analytic sample of this study (T1 hereafter). About 9 years later, MIDUS III rolled out (2013–2014) and reassessed

Predictor: composite sleep health

We relied on six indicators (i.e., regularity, satisfaction, alertness, timing, efficiency, and duration) to assess an individual's sleep health. We converted each of these indicators to binary values, where unfavorable conditions were coded as 1 and favorable conditions were coded as 0 (described in more detail below). To create binary variables, we used existing clinical and scientific guidelines to identify values of unfavorable sleep characteristics wherever possible (e.g., Watson et al.,

Descriptive statistics

Sample characteristics and descriptive statistics of main variables can be seen in Table 1. Summing across the six dimensions of sleep health problems, on average, participants had 2.30 sleep health problems (SD = 1.41). Correlations among sleep variables (Appendix Table 1) ranged from 0.03 to 0.49, indicating that individual sleep dimensions were generally related, but not highly overlapped with each other. The highest correlation was observed between sleep efficiency and sleep duration.

Discussion

Using a sleep health perspective that highlights the importance of multiple sleep characteristics for overall health and functioning (Buysse, 2014), this study examined whether a composite measure of sleep health was associated with psychological and physical well-being in a sample of U.S. adults. We found that more sleep health problems across six dimensions (regularity, satisfaction, alertness, timing, efficiency, and duration) were uniquely associated with higher perceived stress and more

Conclusions

This study contributes empirical evidence to the literature on sleep health and well-being, suggesting that a composite measure of sleep health explains additional variance in adult well-being that a single sleep variable does not explain. Among the multiple sleep health dimensions, sleep satisfaction was mostly consistently and strongly associated with adult well-being. The benefit of sleep health observed in this study is found for both psychological and physical well-being domains and

Acknowledgements

Since 1995 the Midlife in the United States Study has been funded by the John D. and Catherine T. MacArthur Foundation Research Network, the National Institute on Aging (P01-AG020166), and the National Institute on Aging (U19-AG051426). Data and documentation for all MIDUS projects are available to other researchers at the Inter-University Consortium for Political and Social Research (ICPSR). In addition to the publicly-available data at ICPSR, a MIDUS-Colectica Portal (midus.colectica.org)

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