Circadian rhythms influence most of our life activities, notably getting up and going to sleep every day. This new edition of Circadian Physiology delves into the mechanisms surrounding how these rhythms work, the physiology and biology behind them, and the latest research on this cutting-edge field. The book also discusses a wide variety of practical topics including the prevention of jet lag, management of shift work, sleep disorders, depression, and the optimal times for physical and intellectual activities. To facilitate its use as a textbook, the book contains summaries, suggestions for further reading, links to pertinent websites, and exercises at the end of each chapter. It also includes software for data analysis, tutorials, and simulation programs discussed throughout the text. In addition, more than a thousand references have been added, resulting in a total of more than 6000 references. The text has been thoroughly updated as a result of major advances in recent years. This edition adds discussion on the anatomical and physiological characterization of photoresponsive ganglionic cells in the mammalian retina, molecular circadian clocks in cells of multiple organs other than the hypothalamus and the pineal gland, and advances in the understanding of post-translational mechanisms in the operation of the molecular clock.