Nocturnal clenching was monitored using a dedicated microprocessor, appropriate EMG amplification and digitisation. The hardware was located at the subject's bedside and the software provided for the real time recording of clenching bruxism, duration of the episode and the severity in electronic values. Forced clenches before retiring and on arousing provided maximal baseline data against which to compare the severity of sleeping clenches. All ten subjects tested were found to brux and two used intensities of effort while asleep that exceeded their maximal conscious clenches.