Nine male subjects were subjected to jet-flight simulation experiments, and their circadian rhythms in sleep, body temperature and plasma melatonin level were determined. Performance test was also carried out. On the first three days, the subjects went to bed at 24 : 00 h and woke up at 8 : 00 h. On the fourth day, they stayed up one night and since then they went to bed at 16: 00 h and woke up at 24 : 00 h, namely their sleep schedule was phase-advanced by 8 hours.
　In one experiment, after the change in sleep schedule bright light of about 5,000 lx was applied in the subjective morning in order to facilitate a phase-advance shift of the circadian rhythms. As a result, the reentrainment of circadian rhythms was accelerated significantly by the bright light application. And the scores of performance test was increased by bright light. The findings indicate that bright light application at an appropriate time of day may alleviate the jet-lag syndrome by facilitating the reentrainment of circadian rhythm.

DESCENTE SPORTS SCIENCE Vol.14/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE