Association between Bone Mineral Density, Sleep Disturbance and Sleep Duration: Results from Observational and Mendelian Randomization Study

Purpose: The relationship between bone health and sleep problems remains controversial across different study conditions. This study aims to investigate the association between sleep disturbances, sleep duration and bone mineral density (BMD) using observational and Mendelian randomization (MR) study. Methods: A total of 6,421 participants from the National Health and Nutrition Examination Survey (NHANES) 2007- 2010 were included in this study. The association between sleep disturbance, sleep duration, and BMD was assessed using multivariable linear regression analysis. Two-sample MR analysis was employed to corroborate the observational study results. Five methods were utilized to estimate causal effects, with the primary approach being the inverse varianceweighted (IVW) analysis. Results: Sleep disturbance exhibited a negative association with BMD in both the femoral neck (β: -0.03; 95% CI, -0.04 to -0.02), and lumbar spine (β: -0.01; 95% CI, -0.02 to 0.00). This association remained significant after adjusting for known confounders, with β values of -0.01 (95% CI, -0.02 to -0.01) for the femoral neck and -0.01 (95% CI, -0.02 to 0.00) for the lumbar spine. No significant association was observed between sleep duration and BMD, and stratification analysis by sleep disturbance yielded similar results. MR analysis appeared to indicate a consistent trend in the causal association between sleep disorder and BMD at the femoral neck using IVW methods (β: -0.039; 95% CI: -0.142 to 0.063), and lumbar spine (β: -0.041; 95% CI: -0.182 to 0.101), and the other 4 methods showed consistent results, although no significant difference was observed. There was no statistical difference found in the MR analysis for the causal relationship between BMD and sleep duration. Conclusions: The study suggests potential causal associations between sleep disorders and a higher risk of bone loss. Additionally, there is no evidence to indicate that extending sleep duration could compensate for bone loss caused by sleep disorders.