Sleep disorders and sleep habits as predictors and risk factors of temporomandibular disorders: A systematic review

Introduction: TMD are directly correlated with a lower quality of life. Pain is bidirectionally related to sleep alteration. Sleep (an essential human habit) may be less efficient through bad quality or disorders that are associated with pain severity in chronic pain conditions. Several TMD patients present multiple sleep disorders. Objective: Systematic review of the relationship between sleep quality or disorders and TMD occurrence, severity and chronicization. Methods: Data sources: Five databases screened till March 2020. Eligibility criteria: Observational studies assessing sleep quality and sleep disorders in adult TMD. TMD occurrence, severity and/or chronicization should be evaluated. Synthesis method: Qualitative analyses trough tables. Results: Poor sleep quality, obstructive sleep apnea and insomnia are more prevalent among TMD patients. TMD occurrence is higher when associated to poor sleep quality but this effect is influenced by other factors. Low sleep quality is also related to severity and chronicity although no causal relation has been advanced. OSA might influence chronicity. Conclusion: TMD occurrence, severity and chronicization are associated to poor sleep quality. OSA may not influence TMD occurrence and insomnia may be related to TMD severity. Direction of the relationship between sleep and TMD is still discussed. Healthcare providers should investigate sleep quality and risks factors for sleep disorders as they may be linked with TMD.