The last three decades have shown that a number of physiologic functions in organisms ranging from single-celled algae to humans are regulated by a system of clocks controlling base levels of activity and responsivity to changes in the environment. This proceedings volume presents 98 contributions reflecting recent advances in the study of biological rhythms in areas such as molecular genetics, cell functions, neurobiology, biochemistry, physiology, and pharmacology, as well as advances in the understanding of how periodicity affects health and disease. The papers are arranged in five molecular, cellular, and genetic aspects of biological rhythms; environmental signals, entrainment, and regulation of biological rhythms; melatonin and the pineal gland; neuroendocrinology , metabolism, and nutrition; and clinical perspectives in experimental medicine. Annotation c. by Book News, Inc., Portland, Or.