Human Performance and Ultradian Biorhythms.

The purpose of the study was to determine if there was an ultradian (circa 100 minute) temporal organization to behavior, and assess the extent to which variations in behavior could be accounted for by this hypothesized systematic rhythmic variation. Methods included analysis of sleep stages in order to determine the intra-sleep ultradian organization, study of continuous human performance over extended time periods in order to detect ultradian rhythms in performance and activity, and studies of sleep electrophysiology and waking performance in which a hypothesized continuity between ultradian rhythms during sleep and waking was investigated. Results were that the intra-sleep ultradian rhythm was demonstrated to be on the order of 100 minutes. Comparable ultradian rhythms in waking performance on signal detection tasks and in gross motor activity were demonstrated. It was not possible to demonstrate any continuity between intra-sleep and extra-sleep ultradian rhythms. It is concluded on the basis of these studies, as well as other available data, that ultradian rhythms, as reflected in gross motor activity and signal detection tasks, do occur in young adults under specified laboratory conditions, but these rhythms account for little of the variance in these measures. Several reprints are included.