Resynchronisation of Circadian Rhythms after Different Types of 9-h Advance Shifts

Abstract

Hypnotics and the hormone melatonin are presently discussed as efficient means to overcome or reduce the impairing effects of jet- lag. In our opinion, however, more natural approaches would be better. One way for achieving this goal is to use "fractional" desynchronization. In our isolation laboratory, an eastward trans- meridian flight over 9 time zones was simulated with a group of 8 subjects. In the first part of the experiment, the time-shift of 9h was reached by prolongation of thewake period by 15h, in the second part it was performed by shortening the sleep period by 6h and the following wake period by 3h, and in the third part the time-shift was carried out in fractions of 6 and 3h on two consecutive days. Regarding the fractional desynchronization, continuous temperature recordings revealed (1) that the adaptation was faster and (2) that the "antidromic effect" (resynchronization by delaying instead of advancing) could be entirely avoided. A proper scheduling of sleep- wake cycle can be a means that would be beneficial for people who badly suffer from jet-lag.