The aim of the present study is to examine whether appearance of pre-meal anticipatory hormone peak and entrainability to daily restricted meal schedule under temporal isolation facility in adult male subjects. Ten subjects were participated in the present study. The subjects stayed in the facility for 15 days. From day 1 to day 2, 3 meals were provided at fixed time (8:00, 12:00, 18:00). Afterwards, meal was provided once a day for 8 days from day 4 to day 11 (restricted meal schedule). During this restricted meal schedule, the subjects were divided into two groups. One group took the meal at fixed time at 18:00. In another group, the time of meal was decided by the subjects themselves. As a result, the pre-meal peak was not detected in plasma melatonin, cortisol, insulin, ghrelin, and leptin in the both two groups. On the other hand, the sleep-wake cycle was entrained to the daily restricted meal schedule with a period of 24 h, whereas circadian rhythm of plasma melatonin was significantly phasedelayed. These finding indicated that the so-called food entrainable circadian rhythm failed to appear in humans under the present conditions, but the meal schedule act as a potent zeitgeber for the sleep-wake cycle but not for the circadian pacemaker.

DESCENTE SPORTS SCIENCE Vol.36/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE