Sleep bruxism and its associations with insomnia and OSA in the general population of Sao Paulo

Sleep bruxism (SB) is characterized by recurrent masticatory muscle activity during sleep with occasional tooth grinding. SB can be concomitant with sleep apnea although its association with insomnia is understudied.

Study objective: Assess the strength of the associations between SB, insomnia and sleep apnea in a general population.

Methods: Data from the 2007 EPISONO general population study (n = 1042; Sao Paulo, Brazil) were reused for the present analyses. The data was collected from polysomnography (PSG) and from a questionnaire. SB could only be assessed as "possible" with self-report questionnaires, but as "definitive" with both self-reports and PSG. Logistic regression and decision tree analyses were performed.

Results: Logistic regression analyses revealed that being male, overweight, obese, having an apnea/hypopnea index (AHI) above 30 and insomnia syndrome are among risk factors for SB (prevalence ratio (PR): 1.5-3.3). A high AHI and insomnia syndrome had similar PRs, 2.7 and 2.8, respectively. Decision tree analysis showed that insomnia syndrome contributed to the predictive accuracy of SB self-report (88%). A similar estimate (91%) was observed with SB PSG data. Correspondence analysis illustrated three age profiles in participants: (1) good sleepers aged 20-35 years, (2) females aged 35-50 years with SB and concomitant insomnia syndrome, and (3) participants aged ≥ 50 years with obesity and sleep apnea.

Conclusions: Insomnia is likely a condition associated with SB, especially in middle-age females, while sleep apnea seems age and gender dependent. Such overlap may influence the treatment decision to achieve best outcomes.

Clinical trial registration: EPISONO study; Clinical trials.gov ID # NCT00596713.

Keywords: Age; Gender; Insomnia; Obesity; Sleep apnea; Sleep bruxism.