Gundel A, Wegmann H M
DFVLR-Institute for Aerospace Medicine, Cologne, F.R.G.
Chronobiol Int. 1989;6(2):147-56. doi: 10.3109/07420528909064625.
In response to eastbound transmeridian flights, which result in zeitgeber phase advance shifts, adaptation of the circadian system to the new time zone by phase delays and advances are observed. The delay response to an advance zeitgeber shift has been called an antidromic response. For the shift at which the transition from an advance to an antidromic response occurs, the term critical shift is introduced. For the study of critical shifts, a flight experiment across nine time zones and numerical simulations of a van der Pol equation have been evaluated. The interest is focussed on the determination of a range for critical abrupt shifts. An abrupt shift means that the ensemble of zeitgebers including geophysical zeitgebers and the rest-activity cycle is shifted immediately in the new time zone. The range of critical advance shifts has been estimated to reach from +7 to +10 hr. In the literature, results were reported which would imply a much wider range. The discussion of these observations shows that the actual shifts were presumably not abrupt in the quoted experiments. The consequences of critical shifts for jet lag symptoms are investigated. If reduced circadian amplitudes and long times taken for the resynchronization contribute to the feeling of jet lag, the symptoms will be worst for shifts close to the critical one, as numerical simulations revealed. Manipulations of such shifts with the aim to alleviate jet lag are discussed.
针对导致昼夜节律相位提前偏移的向东跨子午线飞行，观察到昼夜节律系统通过相位延迟和提前来适应新的时区。对提前的授时因子偏移的延迟反应被称为逆向反应。对于从提前反应转变为逆向反应的偏移，引入了“临界偏移”这一术语。为了研究临界偏移，评估了一项跨越九个时区的飞行实验以及范德波尔方程的数值模拟。研究重点在于确定临界突然偏移的范围。突然偏移意味着包括地球物理授时因子和休息 - 活动周期在内的授时因子集合在新的时区立即发生偏移。临界提前偏移的范围估计为从 +7 小时到 +10 小时。在文献中，报道的结果似乎暗示了一个更宽的范围。对这些观察结果的讨论表明，在引用的实验中实际的偏移可能并非突然发生。研究了临界偏移对时差反应症状的影响。正如数值模拟所揭示的，如果昼夜节律振幅降低以及重新同步所需的长时间导致时差反应的感觉，那么对于接近临界值的偏移，症状将最为严重。讨论了旨在减轻时差反应而对这种偏移进行的调整。
