Folkard S, Minors D S, Waterhouse J M
MRC/ESRC Social and Applied Psychology Unit, University of Sheffield, England.
J Biol Rhythms. 1991 Spring;6(1):81-91. doi: 10.1177/074873049100600109.
Simulated time zone transitions were performed in an isolation unit upon groups of one to four human subjects. In the first series of experiments, the adjustment of the circadian rhythm of body temperature, measured in the presence of sleep and other masking factors, was assessed by cosinor analysis and by cross-correlation methods. These methods modeled the circadian timing system either as a single component or as the sum of two components, those due to exogenous and endogenous influences. The one-component models described a more rapid adjustment of the temperature rhythm to the time zone transition than did the two-component models; we attribute this difference to the masking effects of the exogenous component. In a second series of experiments, we showed that the shift of the endogenous component, as assessed by the two-component models, was not significantly different from that measured during constant routines. The results also showed that, if the zeitgebers were phased in advance of the endogenous component, then advances of the endogenous component were produced only if this mismatch was less than about 10 hr. Mismatches greater than this, and cases where the zeitgebers were delayed with respect to the endogenous component, both produced delays of the endogenous component. We conclude that the two-component cross-correlation methods can be used to estimate shifts of the endogenous component of a circadian rhythm in the presence of masking factors. They are therefore an alternative to constant routines when these latter are impracticable to carry out.
在一个隔离单元中，对一至四名人类受试者进行了模拟时区转换。在第一系列实验中，通过余弦分析和互相关方法评估了在睡眠和其他掩盖因素存在的情况下测量的体温昼夜节律的调整。这些方法将昼夜节律计时系统建模为单个成分或两个成分的总和，即外源性和内源性影响的成分。单成分模型描述的温度节律对时区转换的调整比双成分模型更快；我们将这种差异归因于外源性成分的掩盖效应。在第二系列实验中，我们表明，通过双成分模型评估的内源性成分的偏移与在固定日常活动期间测量的偏移没有显著差异。结果还表明，如果时间线索比内源性成分提前相位，那么只有当这种不匹配小于约10小时时，才会产生内源性成分的提前。大于此的不匹配以及时间线索相对于内源性成分延迟的情况，都会导致内源性成分的延迟。我们得出结论，双成分互相关方法可用于在存在掩盖因素的情况下估计昼夜节律内源性成分的偏移。因此，当固定日常活动难以实施时，它们是一种替代方法。
