Effects of rapid round trips against time displacement on adrenal cortical-medullary circadian rhythms

The effects of rapid round trips against time displacement on circadian rhythms was investigated. The study was carried out on three occasions using one volunteer healthy physician on east-west trips (Tokyo-San Francisco-Tokyo) of short and prolonged stays. The control study was performed on a north-south trip (Tokyo-Sydney-Tokyo) which had practically no time displacement. The circadian rhythms of urinary 17-OHCS, 17-KS, and noradrenaline excretions and plasma cortisol in short-stay trips were disrupted and not synchronized; however, the recovery was rapid with the circadian rhythms returning to normal within 1 to 2 d. On the other hand, the circadian rhythms of these variables in the control study were not disrupted. These results suggest that a short, overnight stay during the trip minimizes the ill effects due to time displacement.