Patterns of masseter muscle activities during sleep in guinea pigs.

Basic neurophysiological mechanisms for sleep bruxism remain unknown. Analyses of masseter muscle activity during sleep in guinea pigs have shown that the duration and activity of masseter bursts differ between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep and that some repetitive burst episodes do occur. Furthermore, masseter bursts occurred in association with a transient heart rate increase. These results suggest that various patterns of masseter bursts occur in association with transient arousal activity during sleep in guinea pigs.