Klerman E B, Dijk D J, Kronauer R E, Czeisler C A
Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.
Am J Physiol. 1996 Jan;270(1 Pt 2):R271-82. doi: 10.1152/ajpregu.1996.270.1.R271.
The sensitivity of the human circadian system to light has been the subject of considerable debate. Using computer simulations of a recent quantitative model for the effects of light on the human circadian system, we investigated these effects of light during different experimental protocols. The results of the simulations indicate that the nonuniform distribution over the circadian cycle of exposure to ordinary room light seen in classical free-run studies, in which subjects select their exposure to light and darkness, can result in an observed period of approximately 25 h, even when the intrinsic period of the subject's endogenous circadian pacemaker is much closer to 24 h. Other simulation results suggest that accurate assessment of the true intrinsic period of the human circadian pacemaker requires low ambient light intensities (approximately 10-15 lx) during scheduled wake episodes, desynchrony of the imposed light-dark cycle from the endogenous circadian oscillator, and a study length of at least 20 days. Although these simulations await further experimental substantiation, they highlight the sensitivity to light of the human circadian system and the potential confounding influence of light on the assessment of the intrinsic period of the circadian pacemaker.
人类昼夜节律系统对光的敏感性一直是相当多争论的主题。我们使用最近关于光对人类昼夜节律系统影响的定量模型进行计算机模拟，研究了不同实验方案下光的这些影响。模拟结果表明，在经典的自由运行研究中观察到的日常室内光暴露在昼夜节律周期上的不均匀分布（在这些研究中，受试者自行选择光照和黑暗暴露时间），即使受试者内源性昼夜节律起搏器的固有周期更接近24小时，也可能导致观察到的周期约为25小时。其他模拟结果表明，要准确评估人类昼夜节律起搏器的真正固有周期，需要在预定的清醒时段保持低环境光照强度（约10 - 15勒克斯），使施加的明暗周期与内源性昼夜节律振荡器不同步，且研究时长至少为20天。尽管这些模拟结果有待进一步的实验证实，但它们突出了人类昼夜节律系统对光的敏感性以及光对昼夜节律起搏器固有周期评估的潜在混杂影响。
