Resynchronization of Ciracadian Rhythms after 9-h Advance Shifts by Different Sleep-Wake Cycles

Kurzfassung

Hypnotics and the hormone melatonin are presently discussed as ef- ficient means to overcomeor reduce the impairing effects of jet-lag. In our opinion, however, more natural approaches would be better appropriate. One way for achieving this goal is to distribute sleep properly over the sleep-wake cycle. In our isolation laboratory, an eastward transmeridian flight over 9 time zones was simulated with a group of 8 subjects. In the first part of the experiment, the time-shift of 9 h was conducted by prolongation of the wake period by 3 h,in the second part it was performed by shortening the sleep period by6 h and the following wake period by 3 h, and in the third part the time-shift was carried out in fractions of 6 and 3 h on two conse- cutive days. The circadian system was assessed by continuously moni- toring ECG and body temperature, and by 3-r collections of urine for hormones and electrolytes. Regarding the fractional desynchronizationcontinuous temperature recording revealed (1) that the adaptation wasfaster and (2) that the "antidromic effect" (resynchronization by delaying instead of advancing) could be entirely avoided. These re- sults were confirmed by the findings from the other rhythmic func- tions (i.e. ECG, excretion rates of potassium and 17-hydroxicortico- steroids). A proper scheduling of sleep-wake cycle can be a means that would be beneficial for people who badly suffer from jet-lag.