Background: Studies have shown a close association between trouble sleeping and obesity in older adults. However, no studies have explored the underlying mechanism of this relationship. The present study was designed to evaluate the roles of depressive symptoms and cognitive function in the association between trouble sleeping and obesity in older American adults.
Methods: A cross-sectional study with 2575 participants (≥60 years old) in the National Health and Nutrition Examination Survey (NHANES) 2011-2014 was used for analysis. Obesity, depressive symptoms, and cognitive function (including Established Consortium for Word Learning in Alzheimer's Disease (CERAD-WL) (immediate learning and recall and delayed recall), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST)) were objectively measured, and trouble sleeping was assessed using a self-reported questionnaire. The moderated mediation analysis was conducted by Hayes' PROCESS macro.
Results: Trouble sleeping was positively associated with obesity among older adults. Depressive symptoms partially and indirectly mediated this association, and DSST moderated the association between trouble sleeping and depressive symptoms. Trouble sleeping had a lower impact on depressive symptoms in older adults with higher cognitive function.
Limitations: The cross-sectional design prevents making causal inferences, and part of self-reported information was not objective enough.
Conclusion: Cognitive function moderated the mediation of depressive symptoms on the indirect, positive association between trouble sleeping and obesity; hence, incorporating methods to strengthen cognitive function and alleviate depressive symptoms may help weak the link between trouble sleeping and obesity among older adults.
Keywords: Cognitive function; Depressive symptoms; Moderated mediation model; Obesity; Trouble sleeping.
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