Is Insomnia Linked to Sleep Bruxism in Adults? A Systematic Review and Meta-Analysis.

Aim: Systematically evaluate the previous literature on the association between insomnia and sleep bruxism (SB) in adults.

Methods: Advanced searches were performed in different databases (PubMed, Embase, LILACS, Scopus and Web of Science) and grey literature until March 2025. Two trained reviewers independently conducted all stages of the review to identify observational studies evaluating the association between insomnia and SB in adults. Methodological quality was assessed using the Newcastle-Ottawa Scale (NOS). A narrative synthesis summarised the main characteristics of the included studies. Meta-analyses were performed to obtain pooled estimates separately for self-reported and polysomnography (PSG)-based SB. Available data on insomnia and SB were converted into odds ratio (OR) with corresponding 95% confidence intervals (CIs).

Results: Of the 1135 records initially identified, 931 were screened by title and abstract, and 23 were assessed in full text. Eight studies met the inclusion criteria for the systematic review, and six were eligible for meta-analysis, comprising a total sample of approximately 6990 adults. The meta-analysis of four studies investigating the association between insomnia and self-reported SB found no statistically significant association under the random-effects model (OR 1.17; 95% CI 0.79-1.72). Likewise, the pooled analysis of studies assessing PSG-based SB also showed no significant association with insomnia (OR 0.91; 95% CI 0.43-1.95).

Conclusion: Our findings indicate a lack of consistent evidence for a significant association between insomnia and SB. This conclusion is further limited by the small number of included studies, the moderate risk of bias in some studies, and the observed heterogeneity.