Most organisms display endogenously produced ∼ 24-hour fluctuations in physiology and behavior, termed circadian rhythms. Circadian rhythms are driven by a transcriptional-translational feedback loop that is hierarchically expressed throughout the brain and body, with the suprachiasmatic nucleus of the hypothalamus serving as the master circadian oscillator at the top of the hierarchy. Appropriate circadian regulation is important for many homeostatic functions including energy regulation. Multiple genes involved in nutrient metabolism display rhythmic oscillations, and metabolically related hormones such as glucagon, insulin, ghrelin, leptin, and corticosterone are released in a circadian fashion. Mice harboring mutations in circadian clock genes alter feeding behavior, endocrine signaling, and dietary fat absorption. Moreover, misalignment between behavioral and molecular circadian clocks can result in obesity in both rodents and humans. Importantly, circadian rhythms are most potently synchronized to the external environment by light information and exposure to light at night potentially disrupts circadian system function. Since the advent of electric lights around the turn of the 20th century, exposure to artificial and irregular light schedules has become commonplace. The increase in exposure to light at night parallels the global increase in the prevalence of obesity and metabolic disorders. In this review, we propose that exposure to light at night alters metabolic function through disruption of the circadian system. We first provide an introduction to the circadian system, with a specific emphasis on the effects of light on circadian rhythms. Next we address interactions between the circadian system and metabolism. Finally, we review current experimental and epidemiological work directly associating exposure to light at night and metabolism.

中文翻译：

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夜间光线对昼夜节律和新陈代谢的影响。

大多数生物体在生理和行为上表现出内生的〜24小时波动，这被称为昼夜节律。昼夜节律是由转录-翻译反馈环驱动的，该环在整个大脑和身体中分层表达，下丘脑的上交叉眼神经核在该层级的顶部充当主要的昼夜节律振荡器。适当的昼夜节律调节对于许多稳态功能（包括能量调节）很重要。与营养物质代谢有关的多个基因表现出节律性振荡，并且与代谢相关的激素（例如胰高血糖素，胰岛素，生长素释放肽，瘦素和皮质酮）以昼夜节律的方式释放。昼夜节律基因中携带突变的小鼠会改变喂养行为，内分泌信号传导和饮食中的脂肪吸收。此外，行为和生物钟之间的偏差可能导致啮齿动物和人类肥胖。重要的是，昼夜节律通过光信息最有效地与外部环境同步，而夜间暴露于光线可能会破坏昼夜节律系统的功能。自20世纪初电灯问世以来，暴露于人工和不规则光照计划中已变得司空见惯。夜间暴露在光线下的增加与肥胖症和代谢紊乱的患病率全球增加平行。在这篇综述中，我们建议晚上暴露于光线通过破坏昼夜节律系统来改变代谢功能。我们首先介绍昼夜节律系统，特别强调光线对昼夜节律的影响。接下来，我们讨论昼夜节律系统与新陈代谢之间的相互作用。最后，我们回顾了当前与夜间光照和新陈代谢直接相关的实验和流行病学工作。