Woelders Tom, Beersma Domien G M, Gordijn Marijke C M, Hut Roelof A, Wams Emma J
Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
Chrono@Work B.V., Groningen, The Netherlands.
J Biol Rhythms. 2017 Jun;32(3):274-286. doi: 10.1177/0748730417696787. Epub 2017 Apr 28.
Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual's daily light perception and intrinsic pacemaker period under free-running conditions. Establishing individual estimates of circadian phase and period can be time-consuming. We show that circadian phase can be accurately predicted (SD = 1.1 h for dim light melatonin onset, DLMO) using 9 days of ambulatory light and activity data as an input to Kronauer's limit-cycle model for the human circadian system. This approach also yields an estimated circadian period of 24.2 h (SD = 0.2 h), with longer periods resulting in later DLMOs. A larger amount of daylight exposure resulted in an earlier DLMO. Individuals with a long circadian period also showed shorter intervals between DLMO and sleep timing. When a field-based estimation of tau can be validated under laboratory studies in a wide variety of individuals, the proposed methods may prove to be essential tools for individualized chronotherapy and light treatment for shift work and jetlag applications. These methods may improve our understanding of fundamental properties of human circadian rhythms under daily living conditions.
光是使昼夜节律起搏器与24小时太阳周期同步（校准）的最有效时间线索。这种校准过程是个体日常光感知与自由运行条件下内在起搏器周期之间的相互作用。确定昼夜节律相位和周期的个体估计可能很耗时。我们表明，使用9天的动态光和活动数据作为人类昼夜节律系统Kronauer极限环模型的输入，可以准确预测昼夜节律相位（暗光褪黑素开始分泌时间，DLMO的标准差为1.1小时）。这种方法还得出了24.2小时的估计昼夜节律周期（标准差为0.2小时），周期越长，DLMO出现得越晚。更多的日光照射会导致更早的DLMO。昼夜节律周期长的个体在DLMO和睡眠时间之间的间隔也较短。当基于现场的τ估计能够在广泛个体的实验室研究中得到验证时，所提出的方法可能被证明是个体化时间治疗以及用于轮班工作和时差应用的光疗的重要工具。这些方法可能会增进我们对日常生活条件下人类昼夜节律基本特性的理解。
