Females with Sleep Bruxism Show Lower Theta and Alpha Electroencephalographic Activity Irrespective of Transient Morning Masticatory Muscle Pain

Abstract

To investigate the hypothesis that the presence of transient morning masticatory muscle pain in young, healthy sleep bruxers (SBr) is associated with sex-related differences in sleep electroencephalographic (EEG) activity. Data on morning masticatory muscle pain and sleep variables were obtained from visual analog scales and a second night of polysomnographic recordings. Nineteen normal control (CTRL) subjects were age- and sex-matched to 62 tooth-grinding SBr. Differences in sleep macrostructure (stage distribution and duration, number of sleep-stage shifts), number of rhythmic masticatory muscle activity (RMMA) events÷ hour, and EEG activity were analyzed blind to subject status. The influence of pain and gender in SBr and CTRL subjects was assessed with the Fisher's exact test, Mann-Whitney U test, two-sample t test, and analysis of variance (ANOVA). Low-intensity morning transient orofacial pain was reported by 71% of SBr, with no sex difference. RMMA event frequency was higher in SB than CTRL subjects (4.5÷hour vs 1.3÷hour; P < .001). SBr had fewer sleep-stage shifts, irrespective of sex or pain status. Female SBr had significantly lower theta and alpha EEG activity compared to female CTRL subjects (P = .03), irrespective of pain. Female SBr had lower theta and alpha EEG activity irrespective of transient morning pain.