Relationship between Circadian Rhythm in Body Temperature and Ultradian Variations of Psychological and Physiological States in Arousal

In order to investigate the relationship between the ultradian variations of psychological and physiological states in arousal and circadian rhythm in body temperature, the physiological and psychological testing of seven subjects was carried out continuously for 13 hours from 9am to 10pm. Diurnal variations in physiological and psychological quantities were analyzed by the maximum entropy method and the least square approximation. As a result of the analysis, three kinds of ultradian component (periods of 1.5, 3.0, and 6.0 hour) were detected. In addition, with regard to the 1.5-hour-cycle component for simple arithmetic operations and heart rates, the interrelation between the period of ultradian variations and the amplitude of the rhythm of body temperature was investigated for each subject; as a result, it was recognized that there were a statistical significant negative correlation (r = -0.72, p<0.05) between body temperature and simple arithmetic operations and a positive correlation (r = 0.95, p<0.001) between body temperature and heart rate. This shows that the cycles of ultradian variations are affected by circadian rhythms, and is important knowledge in considering the essence of ultradian rhythm.