The timing of life on Earth is remarkable: between individuals of the same species, a highly similar temporal pattern is observed, with shared periods of activity and inactivity each day. At the individual level, this means that over the course of a single day, a person alternates between two states. They are either upright, active, and communicative or they lie down in a state of (un)consciousness called sleep where even the characteristic of neuronal signals in the brain shows distinctive properties. The circadian clock governs both of these time stamps—activity and (apparent) inactivity—making them come and go consistently at the same approximate time each day. This behavior thus represents the meeting of two pervasive systems: the circadian clock and metabolism. In this article, we will describe what is known about how the circadian clock anticipates daily changes in oxygen usage, how circadian clock regulation may relate to normal physiology, and to hypoxia and ischemia that can result from pathologies such as myocardial infarction and stroke.

中文翻译：

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昼夜节律时钟和缺氧

地球上生命的时间安排是引人注目的：在同一物种的个体之间，观察到高度相似的时间模式，每天都有共同的活动和不活动时期。在个人层面上，这意味着在一天的时间内，一个人在两种状态之间交替。它们要么是直立的、活跃的、善于交流的，要么是处于一种称为睡眠的（无）意识状态，在这种状态下，甚至大脑中神经元信号的特征也显示出独特的特性。生物钟控制着这两个时间戳——活动和（明显的）不活动——使它们每天在相同的大致时间一致地出现和消失。因此，这种行为代表了两个普遍系统的相遇：生物钟和新陈代谢。在本文中，我们将描述生物钟如何预测每日用氧量的变化、生物钟调节如何与正常生理机能以及心肌梗塞和中风等病理导致的缺氧和缺血之间的关系。