Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans
Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans
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DOI：
10.1073/pnas.201530198
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发表时间：
2001-11-20
影响因子：
11.1
通讯作者：
Czeisler, CA
中科院分区：
文献类型：
--
作者：
Wright, KP;Hughes, RJ;Czeisler, CA
内源性生物钟是生理和行为的强大调节器。生物钟与环境时间的同步或夹带对于生理稳态和物种特异性行为的适当定时是适应性的和重要的。我们在实验室中对受试者进行了长达55天的研究，以确定在三个大约24小时的时间段（23.5、24.0和24.6小时）将人体生物钟引入弱昼夜同步刺激（在非常昏暗（注视角度约为1.5勒克斯）的光暗周期中预定的活动-休息周期）的能力。这些研究使我们能够测试两个相互竞争的假设，即人类昼夜节律起搏器的周期是否接近或远长于24小时。我们在这里报告说，实施一个睡眠-觉醒时间表，在清醒期间暴露于相当于烛光的光线下，在睡眠期间暴露于黑暗中，通常足以维持昼夜节律到24小时，但不能维持到23.5小时或24.6小时。我们的研究结果从功能上证明，在正常视力的成年人中，人类生物钟的平均固有昼夜节律周期非常接近24小时。暴露于非常昏暗的光线和/或预定的睡眠-觉醒周期本身可以将人类昼夜节律起搏器的近24小时内在周期带入24小时。
Endogenous circadian clocks are robust regulators of physiology and behavior. Synchronization or entrainment of biological clocks to environmental time is adaptive and important for physiological homeostasis and for the proper timing of species-specific behaviors. We studied subjects in the laboratory for up to 55 days each to determine the ability to entrain the human clock to a weak circadian synchronizing stimulus [scheduled activity-rest cycle in very dim (approximate to1.5 lux in the angle of gaze) light-dark cycle] at three approximate to 24-h periods: 23.5, 24.0, and 24.6 h. These studies allowed us to test two competing hypotheses as to whether the period of the human circadian pacemaker is near to or much longer than 24 h. We report here that imposition of a sleep-wake schedule with exposure to the equivalent of candlelight during wakefulness and darkness during sleep is usually sufficient to maintain circadian entrainment to the 24-h day but not to a 23.5- or 24.6-h day. Our results demonstrate functionally that, in normally entrained sighted adults, the average intrinsic circadian period of the human biological clock is very close to 24 h. Either exposure to very dim light and/or the scheduled sleep-wake cycle itself can entrain this near-24-h intrinsic period of the human circadian pacemaker to the 24-h day.