Awakening salivary cortisol levels of children with sleep bruxism.UNLABELLED:  The study of factors potentially associated with sleep bruxism (SB) may contribute to a better understanding of its nature and etiology. OBJECTIVES:  In this way, this cross-sectional study aimed to evaluate the association between SB and salivary cortisol levels, heart rate, and other parafunctional habits. DESIGN AND METHODS:  Data were collected in 100 healthy caries-free children of both genders, aged 7.23 ± 0.60 years, with (n=27) and without (n=73) signs and symptoms of SB by interview with the parents and clinical and physical examination. Salivary cortisol was measured immediately after waking up and 30min after awakening for the determination of the area under the response curve (AURC). Data were analyzed by descriptive statistics, normality test, and Spearman correlation test; a stepwise logistic regression model was used to verify the association between SB, as the dependent variable, and age, gender, body mass index (BMI), heart rate, presence of sucking habit, nail biting, enuresis, and AURC (α=0.05). RESULTS:  AURC did not correlate with BMI and heart rate. Only AURC showed a significant negative association with SB, while age, gender, BMI, heart rate and other parafunctional habits did not associate with SB. CONCLUSION:  In the studied sample, children with SB were more likely to present low concentrations of awakening salivary cortisol.