Association between the hemoglobin-to-red cell distribution width ratio and poor sleep quality in US adults

BACKGROUND: This study aims to investigate the relationship between hemoglobin-to-red blood cell distribution width ratio (HRR) and sleep quality, with a particular focus on whether depression influences this association. METHODS: This study utilized data from 20,823 participants drawn from the 2005-2014 cycles of the National Health and Nutrition Examination Survey (NHANES). Sleep quality was primarily evaluated through self-reported questionnaires assessing the presence of sleep problems or disorders. The HRR was defined as the ratio of hemoglobin (HB) to red cell distribution width (RDW). We used directed acyclic graphs (DAGs) to pre-identify relevant covariates, variance inflation factors (VIF) to exclude highly collinear variables, and the Boruta algorithm to assist in covariate selection, and explored the relationship between HRR and sleep quality through multivariable logistic regression, restricted cubic spline (RCS) modeling, threshold effect analysis, and subgroup analysis. Furthermore, we performed sensitivity analyses to evaluate the robustness of the model and used mediation analysis to exploratorily investigate the potential mediating effect of depression in this relationship. RESULTS: This study involved 20,823 participants. After adjusting for all covariates via multivariable logistic regression, Under the unweighted condition, the prevalence of sleep disorders, sleep problems, and depression were 8.49% (1769/20823), 24.82% (5170/20823), and 8.71% (1814/20823), respectively. HRR was significantly negatively associated with sleep disorders (OR = 0.2870, 95% CI: 0.2044, 0.4042), sleep problems (OR = 0.4847, 95% CI: 0.3853, 0.6101), and depression (OR = 0.6460, 95% CI: 0.4603, 0.9093). The findings were consistent after applying the appropriate weighting to the models. Furthermore, exploratory mediation analysis indicated that depression mediated 10.59% (P < 0.001) of the association between HRR and sleep disorders, and 23.14% (P < 0.001) of the association between HRR and sleep problems. CONCLUSION: This study revealed a robust inverse relationship between HRR and sleep quality. The exploratory analysis provided partial evidence that depressive symptoms served as a mediating factor in the relationship between the two variables.