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There's More to Sleep than Counting Sheep: A Cross Sectional Analysis of Sleep Health
Elizabeth Torres, Depts. of Psychology, Biology, and Chemistry, Sanika Lawate, Hali Russell, and Emily Donovan, M.S., and Pablo Soto, Dept. of Psychology Graduate Students, with Dr. Joseph Dzierzewski, Dept. of Psychology
Background: Studies have supported the claim that good physical health and positive affect have a lasting positive impact on the body and the brain across all age groups. High levels of activity and positive affect can boost immunity, increase life expectancy, and promote resiliency. Studies have also shown that poor physical health and low affect can negatively impact sleep quality. While the associations among physical health, affect, and sleep have been examined, the present study aims to extend these findings to sleep health, a newly developed construct which aims to emphasize the benefits of sleep, rather than the negative effects of the absence of sleep. The purpose of this study is to determine the predictive power of affect for sleep health above and beyond age and physical health, in a large sample of adults. Methods: Data from this study were drawn from a larger online survey investigating sleep and health outcomes across various developmental stages. In this study, physical health, affect, and sleep health were self-reported. Sleep health was measured using the RU-SATED, and affect was measured using the Positive and Negative Affect Schedule (PANAS). Physical health was measured as the total number of self-reported medical conditions from a list of common conditions. A hierarchical linear regression was conducted, with age in block 1, physical health in block 2, positive and negative affect in block 3, and sleep health as a dependent variable. Results: A three-level hierarchical linear regression was computed to investigate if affect predicted sleep health above and beyond age and physical health. When age was entered, it predicted sleep health, F(1, 3282) = 61.87, p < .001, R2 = .019. This initial model revealed that 1.9% of the variance in sleep health was predicted by knowing the participant’s age. When physical health was entered, it predicted sleep health, ∆F(1, 3281) = 78.53, p < .001, ∆R2 = .023. This model revealed that an additional 2.3% of the variance in sleep health was predicted by knowing the participant’s physical health. When positive and negative affect were added to the model, they significantly improved prediction, ∆F(2, 3279) = 178.26, p < .001, ∆R2 = .094, revealing that an additional 9.4% of the variance in sleep health was explained by positive and negative affect. All variables together significantly predicted sleep health outcomes, F(4, 3279) = 128.43, p < .001, R2 = .135, with 13.5% variance in sleep health explained. In the final model, age (β = .10, p < .001), physical health (β = -.09, p < .001), positive affect (β = .17, p < .001), and negative affect (β = -.24, p < .001) were significant predictors of sleep health. Conclusion: The current study suggests that affect predicts sleep health above and beyond age and physical health. Greater positive affect and fewer chronic health conditions are associated with better sleep health. Inversely, greater negative affect and more chronic health conditions negatively are associated with worse sleep health. Therefore, people who have higher negative affect (i.e., negative emotions, including anger, contempt, disgust, guilt, fear, and nervousness as well as low self-concept) report poorer sleep. Future studies would benefit from a longitudinal design to examine the associations among positive affect, physical health, and sleep health over time. Moreover, studies could incorporate clinical samples with chronic medical conditions to further explore the associations among affect, physical health, and sleep health. Given the strong association between affect and sleep health, future studies could also explore interventions that foster positive affect to see if manipulation of affect improves sleep health.
Joseph Dzierzewski, Ph.D.
Virginia Commonwealth University. Undergraduate Research Opportunities Program
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VCU Undergraduate Research Posters
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