昼夜节律是一种定时机制，几乎所有生物种类的细胞和生理功能会产生大约24小时的节律。这些内部时钟系统使生物能够预测和应对环境中每天的变化，优化时间生理和行为。昼夜节律受遗传和环境风险因素的调控。昼夜节律在系统和组织水平上维持稳态具有重要作用。这种节律的紊乱为人类健康和疾病奠定基础。这些节律的紊乱增加了许多疾病（如癌症、精神障碍和神经退行性疾病）的易感性。本章将讨论昼夜节律的特征及其与疾病的关系。版权所有 © 2023. Elsevier Inc.出版。

The circadian rhythm is the timing mechanism that creates approximately 24-hour rhythms in cellular and bodily functions in almost all living species. These internal clock systems enable living organisms to predict and respond to daily changes in their environment, optimizing temporal physiology and behavior. Circadian rhythms are regulated by both genetic and environmental risk factors. Circadian rhythms play an important role in maintaining homeostasis at the systemic and tissue levels. Disruption of this rhythm lays the groundwork for human health and disease. Disruption in these rhythms increases the susceptibility to many diseases, such as cancer, psychiatric disorders, and neurodegenerative diseases. In this chapter, the characteristics of circadian rhythm and its relationship with diseases will be discussed.Copyright © 2023. Published by Elsevier Inc.