Phillips A J K, Chen P Y, Robinson P A
School of Physics, University of Sydney, New South Wales, Australia.
J Biol Rhythms. 2010 Jun;25(3):217-27. doi: 10.1177/0748730410369208.
The physiological mechanisms underlying interindividual differences in chronotype have yet to be established, although evidence suggests both circadian and homeostatic processes are involved. A physiologically based model is developed by combining models of the sleep-wake switch and circadian pacemaker, providing a means of examining how interactions between these systems affect chronotype. Specifically, chronotype is shown to depend on the relative influences of homeostatic and circadian drives, with a stronger homeostatic drive causing morningness. Changes to intrinsic circadian and homeostatic properties, including homeostatic clearance and production rates, and circadian period and amplitude, are also shown to affect chronotype. These results provide a framework for explaining several experimentally observed phenomena, including age-related morningness, adolescent eveningness, and familial advanced and delayed sleep-phase disorders. Additionally, experimental studies have shown that healthy adults on the extremes of the morningness-eveningness spectrum fall into two subtypes: those whose circadian phase markers are unaffected by chronotype, and those whose circadian phase markers track their chronotype. The model demonstrates that this spectrum likely results from interindividual differences in homeostatic kinetics in the first group, and differences in circadian period in the second group. Physiologically based modeling can thus guide diagnosis of sleep pathologies.
尽管有证据表明昼夜节律和稳态过程都参与其中，但个体间昼夜节律类型差异背后的生理机制尚未明确。通过结合睡眠 - 觉醒开关模型和昼夜节律起搏器模型，构建了一个基于生理的模型，为研究这些系统之间的相互作用如何影响昼夜节律类型提供了一种方法。具体而言，昼夜节律类型显示取决于稳态驱动力和昼夜节律驱动力的相对影响，稳态驱动力越强导致越倾向于早晨型。内在昼夜节律和稳态特性的变化，包括稳态清除率和生成率，以及昼夜节律周期和振幅，也显示会影响昼夜节律类型。这些结果为解释一些实验观察到的现象提供了一个框架，包括与年龄相关的早晨型、青少年的夜晚型，以及家族性的早睡型和晚睡型睡眠相位障碍。此外，实验研究表明，处于早晨型 - 夜晚型频谱两端的健康成年人可分为两种亚型：一种是其昼夜节律相位标记不受昼夜节律类型影响的人，另一种是其昼夜节律相位标记跟踪其昼夜节律类型的人。该模型表明，这种频谱可能是由于第一组中个体稳态动力学的差异，以及第二组中昼夜节律周期的差异所致。基于生理的建模因此可以指导睡眠病理学的诊断。
