Sack R L, Lewy A J
Department of Psychiatry, School of Medicine, Oregon Health Sciences University, Portland 97201, USA.
J Biol Rhythms. 1997 Dec;12(6):595-603. doi: 10.1177/074873049701200615.
Although the causes are different, totally blind people (without light perception) and night shift workers have in common recurrent bouts of insomnia and wake-time sleepiness that occur when their preferred (or mandated) sleep and wake times are out of synchrony with their endogenous circadian rhythms. In this article, the patterns of circadian desynchrony in these two populations are briefly reviewed with special emphasis on longitudinal studies in individual subjects that used the timing of melatonin secretion as a circadian marker. In totally blind people, the most commonly observed pattern is a free-running rhythm with a stable non-24-h circadian period (24.2-24.5 h), although some subjectively blind people are normally entrained, perhaps by residually intact retinoypothalamic photic pathways. Experiments at the cellular and behavioral levels have shown that melatonin can produce time dependent circadian phase shifts. With this in mind, melatonin has been administered to blind people in an attempt to entrain abnormal circadian rhythms, and substantial phase shifts have been accomplished; however, it remains to be demonstrated unequivocally that normal long-term entrainment can be produced. In untreated night shift workers, the degree and direction of phase shifting in response to an inverted sleep-wake schedule appears to be quite variable. When given at the optimal circadian time, melatonin treatment appears to facilitate phase shifting in the desired direction. Melatonin given prior to a night worker's daytime sleep also may attenuate interference from the circadian alerting process. Because melatonin has both phase-shifting and sleep-promoting actions, night shift workers, who number in the millions, may be the most likely group to benefit from treatment.
尽管原因不同，但全盲者（无光感）和夜班工作者有一个共同之处，即当他们偏好的（或规定的）睡眠和清醒时间与内源性昼夜节律不同步时，都会反复出现失眠和清醒时困倦的情况。在本文中，将简要回顾这两类人群的昼夜节律失调模式，特别强调针对个体受试者的纵向研究，这些研究将褪黑素分泌时间作为昼夜节律标记。在全盲者中，最常见的模式是具有稳定的非24小时昼夜周期（24.2 - 24.5小时）的自由运行节律，不过一些主观上失明的人可能通常能被内源性昼夜节律所调节，这可能是由于视网膜 - 下丘脑光通路仍有残余功能。细胞和行为水平的实验表明，褪黑素可产生时间依赖性的昼夜节律相位偏移。基于此，已对盲人使用褪黑素以试图调节异常的昼夜节律，并且已实现了显著的相位偏移；然而，能否明确产生正常的长期调节仍有待证明。在未经治疗的夜班工作者中，对颠倒的睡眠 - 清醒时间表的相位偏移程度和方向似乎变化很大。在最佳昼夜节律时间给予褪黑素治疗，似乎有助于向期望方向的相位偏移。在夜班工作者白天睡眠前给予褪黑素也可能减轻昼夜警觉过程的干扰。由于褪黑素兼具相位偏移和促进睡眠的作用，数以百万计的夜班工作者可能是最有可能从治疗中受益的群体。
