Minute eye movement during sleep.

The minute eye movements of 4 sleeping subjects were studied with a piezo-electric strain-gauge transducer. The frequency and amplitude of ocular microtremor activity diminished during sleep. Activity increased after auditory stimulation and with the appearance of a K complex in the EEG. The ocular microtremor activity also increased with the onset of rapid eye movement (REM). Low amplitude 'micronystagmoid' movements were observed at intervals throughout sleep. In contrast to the changes observed during sleep, ocular microtremor activity did not diminish during hypnosis. The transducer was far more sensitive than the conventional EOG recording system.