Monk T H
Sleep Evaluation Center, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pennsylvania 15213.
Exp Gerontol. 1991;26(2-3):233-43. doi: 10.1016/0531-5565(91)90015-e.
The human biological clock or "circadian system" serves the function of preparing the body and mind for restful sleep at some times of day and active wakefulness at others. The observed circadian rhythms result from three interacting processes: endogenous rhythm generation mechanisms, entrainment mechanisms to keep these rhythms "on track," and exogenous masking processes stemming from changes in environment and behavior. In both advanced age and extraterrestrial travel these processes, particularly the latter two, can be dramatically effected with a consequent disruption in sleep and daytime functioning. We are currently studying the age-related effects on these processes in healthy 80 year olds using two different protocols. The first involved 36 h of constant wakeful bedrest which "unmasked" the endogenous component of circadian rhythms in various physiological and psychological functions. This experiment revealed little difference between nine old men and four young men in the endogenous body temperature rhythm, but revealed quite marked differences between the age groups in subjective activation and objective performance rhythms. A similar pattern occurred in the second experiment, which was a phase shift study comparing five old women with eight middle-aged men in their response to an acute 6 h phase advance in routine. Despite rather short-lived age-related differences in circadian rhythms, there were dramatic differences between the age groups in measures of sleep, mood, activation, and performance efficiency lasting for a week or more after the phase shift.
人类生物钟或“昼夜节律系统”的功能是，在一天中的某些时段让身心为安稳睡眠做好准备，而在其他时段则为活跃清醒做好准备。观察到的昼夜节律源自三个相互作用的过程：内源性节律产生机制、使这些节律“步入正轨”的同步化机制，以及源自环境和行为变化的外源性掩盖过程。在高龄和太空旅行中，这些过程，尤其是后两个过程，可能会受到显著影响，进而导致睡眠和日间功能紊乱。我们目前正在使用两种不同的方案，研究健康的80岁老人中这些过程的年龄相关影响。第一个方案涉及36小时持续卧床清醒，这“揭开了”各种生理和心理功能中昼夜节律的内源性成分。该实验显示，9名老年男性和4名年轻男性在内源性体温节律方面几乎没有差异，但在主观激活和客观表现节律方面，年龄组之间存在相当明显的差异。第二个实验也出现了类似的模式，这是一项相位偏移研究，比较了5名老年女性和8名中年男性对日常安排中急性提前6小时相位的反应。尽管昼夜节律中与年龄相关的差异持续时间较短，但在相位偏移后长达一周或更长时间内，年龄组之间在睡眠、情绪、激活和表现效率等指标上存在显著差异。
