Six normal adult subjects were studied during all stages of sleep for a total of 14 nights to determine whether nystagmus could be elicited by vestibular stimulation, particularly during the rapid eye movement (REM) sleep stage. Perrotatory vestibular stimulation was induced by means of a constant angle torsion swing. At no time during REM sleep was nystagmus evoked by vestibular stimulation. In addition, no clear nystagmic responses were elicited during non-REM stages 2, 3, and 4. In all stages of sleep, rotation of the torsion swing always produced slow, compensatory conjugate eye movements. With the onset of rotational stimulation during the REM sleep stage, REM bursts were suppressed but emerged immediately following termination of stimulation; phasic activity of the chin muscles was unaffected, however, during REM sleep by rotational stimulation.