Insomnia as a risk factor for temporomandibular disorders: a nationwide population-based cohort study

Objective: Temporomandibular disorders (TMD) significantly impact quality of life, and insomnia has emerged as a potential contributing factor. This study aimed to evaluate the association between clinically diagnosed insomnia and the risk of developing TMD using nationwide data from the Korean National Health Insurance Service (NHIS). Methods: We collected baseline data from 2011 to 2014 using the NHIS database and followed participants until 2019. A total of 358,475 adults without previous insomnia or TMD were analyzed, and propensity score matching (1:3) was performed to create balanced insomnia (n = 20,813) and non-insomnia (n = 62,439) cohorts. Insomnia was defined using diagnostic codes combined with prescription records. Cox proportional hazards models and Kaplan-Meier estimates were employed to evaluate the TMD incidence over a follow-up period ending in 2019. Results: Individuals with insomnia exhibited a significantly higher incidence of TMD (6.46 vs. 4.48 per 1,000 person-years). Even after adjusting for demographic, lifestyle, and clinical variables, insomnia remained a significant independent predictor of TMD, with a 36% increased risk (HR = 1.36; 95% CI: 1.25–1.49). Kaplan-Meier analysis confirmed a consistently higher cumulative incidence of TMD among insomnia patients (p < 0.001). Conclusion: Clinically diagnosed insomnia was found to be associated with an increased risk of developing TMD. However, as this study was based on the NHIS database, causality cannot be definitively established. Nonetheless, these findings suggest that incorporating sleep disturbances assessments into the evaluation and management of TMD may be beneficial. Further prospective studies are warranted to clarify this association and assess the potential benefits of integrated care strategies.