The causal association between sleep traits and osteoarthritis traits: evidence from bidirectional mendelian randomization.

Sleep disorder is associated with risk of osteoarthritis, yet their causal association has not been fully understood. This study aims to evaluate the causal association between sleep traits and osteoarthritis, by performing two sample Mendelian randomization (MR) leveraging the currently largest genome-wide association study (GWAS) summary statistics for sleep traits and osteoarthritis traits. We demonstrate that insomnia has a risk-increasing causal effect on osteoarthritis at any site, hip osteoarthritis, and hip and/or knee osteoarthritis, corresponding to approximately 60%, 100%, and 50% higher odds of disease, respectively, with the strongest effect observed for hip osteoarthritis. Conversely, genetic predisposition to osteoarthritis at any site was associated with a modest 4% increase in the odds of insomnia. These findings reveal a bidirectional causal relationship between insomnia and osteoarthritis-related traits, underscoring the critical interplay between sleep health and joint disease, and suggesting opportunities for preventive and therapeutic strategies that align with the body's intrinsic timing systems.