Association between sleep bruxism and stress symptoms in adults: A systematic review and meta-analysis

To synthesise and critically review the association between sleep bruxism (SB) and stress symptoms in adults. A systematic review was performed. The search was completed using seven primary electronic databases in addition to a grey literature search. Two reviewers blindly selected studies based on pre-defined eligibility criteria. Risk of bias of the included articles was performed using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional Studies. RevMan 5.4 was used to perform the meta-analysis. The quality of evidence was evaluated according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Ten studies were included for qualitative analysis, of which three were included for quantitative analysis. Three studies were evaluated to have low risk of bias, and seven were assessed with moderate risk of bias. Quality of evidence was classified as very low for all outcomes. Individuals with SB were found to have higher levels of some self-reported stress symptoms as assessed through questionnaires with a mean difference of 4.59 (95% CI 0.26-8.92). Biomarkers like epinephrine, norepinephrine, cortisol, adrenaline, dopamine, noradrenaline and prolidase enzyme levels also showed a positive association with SB. Although some associations were identified between probable SB and self-reported stress symptoms and biomarkers of stress in adults, given that the quality of evidence was found to be very low, caution should be exercised in interpreting these results. These findings suggest that additional and better designed studies are warranted in order to clarify the link between SB and stress.