Depressive symptoms mediate the association between sleep duration and chronic low back pain in US adults: evidence from the 2009-2010 NHANES

Background The relationship between sleep duration and the risk of developing chronic low back pain (CLBP) remains unclear. This study aimed to investigate the association between sleep duration and CLBP, as well as the mediating effect of depressive symptoms. Methods Data from the 2009-2010 US National Health and Nutrition Examination Survey (NHANES) were used, including 4807 adults aged ≥18 years. Multivariable logistic regression analysis was performed to assess the relationship between sleep duration and CLBP. Mediation analysis was conducted to quantify the effect of depressive symptoms on this association. Additionally, restricted cubic splines (RCS) were used to evaluate potential nonlinear relationships. Results A total of 4807 participants were recruited, with a mean age of 49.43 ± 17.75 years, and a CLBP prevalence of 10.56% (508/4,807). Multivariable logistic regression analysis revealed that compared to the reference group, the first and third tertiles of sleep duration were associated with an increased incidence of CLBP. A nonlinear U-shaped association was found between sleep duration and CLBP, with an inflection point at 8 hours of sleep. The odds ratios (95% confidence intervals) for CLBP were 0.75 (0.70, 0.81) and 1.37 (1.14, 1.65) below and above this inflection point, respectively. Mediation analysis indicated that depressive symptoms mediated 30.56% of the association between sleep duration and CLBP. Subgroup analysis identified physical activity (interaction P = 0.007) and cardiovascular diseases (interaction P = 0.009) as interaction factors. Conclusion This study demonstrates that both short and long sleep duration are associated with an increased incidence of CLBP, following a nonlinear U-shaped pattern. This association is partially mediated by depressive symptoms, suggesting that sleep duration may be a valuable predictor of adverse prognosis for CLBP in adults.