Human Circadian Rhythms

Circadian Rhythms and the Human covers the basic principles behind the human circadian rhythms. This book is composed of 12 chapters that discuss the detection, analysis, and definition of rhythms, specifically exogenous and endogenous rhythms. This book also demonstrates the mechanism of metabolic and gastrointestinal rhythms. The opening chapters deal with the rhythms in living organism; establishing the endogeneity of rhythms; definition of nychthemeral rhythm; methods of measuring the frequency of rhythms; exogenous effects upon the temperature rhythm; interaction between exogenous and endogenous influences; and possible origins of renal rhythmicity. The succeeding chapters consider the effect of exercise at different times of day and the concept of sleep-wakefulness rhythm. The discussion then shifts to the effects of repeated time-zone transitions and the effects of time on drug administration. The closing chapters are devoted to the assessment of work performance during shift work. The book can provide useful information to doctors, students, researchers, and the general reader.

Biological rhythmicity has been a subject of scientific research for a relatively short time. In the special case of daily, or circadian rhythms, it is only during the past twenty years that rapidly increasing efforts have been undertaken in evaluat ing properties and mechanisms. As a consequence of these efforts, the study of biological and, in particular, circadian rhythmicity is no longer a somewhat dubious occupation but rather a serious branch of science which combines the interdisciplinary efforts of numerous researchers around the world. The general result of these efforts is that many features of circadian rhythms of many different species of living beings are well known today. In addition to studies with lower organisms, the evaluation of human circadian rhythms was originally more or less a compulsory exercise done in order to extend the "catalogue of species"; of course, the work was of unusual impor tance due to the special position of man in biology. In the course of the very first experimental series, it became clear that humans possess an "internal clock" as had been established in various organisms, protists, plants, and animals, and that human circadian rhythms fit the general regularities of biological rhythms known at that time. However, it soon became apparent that circadian rhythmicity of man shows, additionally, particularities of great general interest, for practical and theoretical reasons.

The earth's daily rotation affects just about every living creature. From dawn through to dusk, there are changes in light, temperature, humidity, and rainfall. However, these changes are regular, rhythmic and, therefore, predictable. Thus, the near 24 hour circadian rhythm is innate: a genetically programmed clock that essentially ticks of its own accord. This Very Short Introduction explains how organisms can "know" the time and reveals what we now understand of the nature and operation of chronobiological processes. Covering variables such as light, the metabolism, human health, and the seasons, Foster and Kreitzman illustrate how jet lag and shift work can impact on human well-being, and consider circadian rhythms alongside a wide range of disorders, from schizophrenia to obesity. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.

With the invitation to edit this volume, I wanted to take the opportunity to assemble reviews on different aspects of circadian clocks and rhythms. Although most c- tributions in this volume focus on mammalian circadian clocks, the historical int- duction and comparative clocks section illustrate the importance of various other organisms in deciphering the mechanisms and principles of circadian biology. Circadian rhythms have been studied for centuries, but only recently, a mole- lar understanding of this process has emerged. This has taken research on circadian clocks from mystic phenomenology to a mechanistic level; chains of molecular events can describe phenomena with remarkable accuracy. Nevertheless, current models of the functioning of circadian clocks are still rudimentary. This is not due to the faultiness of discovered mechanisms, but due to the lack of undiscovered processes involved in contributing to circadian rhythmicity. We know for example, that the general circadian mechanism is not regulated equally in all tissues of m- mals. Hence, a lot still needs to be discovered to get a full understanding of cir- dian rhythms at the systems level. In this respect, technology has advanced at high speed in the last years and provided us with data illustrating the sheer complexity of regulation of physiological processes in organisms. To handle this information, computer aided integration of the results is of utmost importance in order to d- cover novel concepts that ultimately need to be tested experimentally.

This book is a concise, comprehensive and up-to-date account of fundamental concepts and potential applications of biological timekeeping mechanisms in animals and humans. It also discusses significant aspects of the organization and importance of timekeeping mechanisms in both groups. Divided into seven sections, it addresses important aspects including fundamental concepts; animal and human clocks; clock interactions; clocks and metabolism and immune functions; pineal, melatonin and timekeeping; and clocks, photoperiodism and seasonal behaviours. The book also focuses on biological clock applications in a 24x7 human society, particularly in connection with life-style associated disorders like obesity and diabetes. It is a valuable resource for advanced undergraduates, researchers and professionals engaged in the study of the science of biological timekeeping.