Sleep movements in teethgrinders.

To investigate the nocturnal motor activity associated with teethgrinding, 12 patients and 12 controls were recorded during sleep with the masseter muscle electromyogram (EMG) and the static charge-sensitive bed movement sensor. The frequency of body movements per hour was 21.4 in the teethgrinders and 14.0 (P less than .05) in the control group. The movement time was 87.4 seconds per hour in the teethgrinders and 55.2 seconds per hour (P less than .01) in the controls. The differences were most obvious in the body movements with temporal association to EMG elevation during the first stage of sleep. The number of isolated EMG elevations showed great interindividual variation and did not differ between groups. The teethgrinders complained more frequently of delayed sleep onset and daytime tiredness. The data suggest that the motor disturbance of teethgrinding is not limited to masticatory muscles but is manifested also as increased general body movement activity.