ABSTRACT
This chapter deals with the history of circadian physiologyfrom ancient times to the present. Before we address its history, we must dene circadian physiology. Physiology (or “integrative biology”) is the study of vital processes of living organisms, particularly at the level of organs and organ systems and at the level of the organism as a whole.1 Because physiological processes are dependent on anatomical and biochemical factors, and because they constitute the physical basis of behavior, the discipline of physiology must incorporate the disciplines of anatomy, endocrinology, molecular biology, pharmacology, neuroscience, and psychology. Circadian physiology is the branch of physiology that deals with the temporal organization of vital processes in the course of a day. Thus, circadian physiology is integrative biology at its best: it deals with the integration of functions in both the spatial and temporal dimensions. A discussion of the conceptual and practical importance of circadian physiology will be initiated in Section 1.3 and will continue throughout this book.
