Hypnos (the Greek god of sleep) and Thanatos (death) were the twin sons of Nyx, the goddess of night (Fox, 1964). Hypnos lived in a dusky valley in the land of the Cimerians, watered by Lethe, the river of forgetfulness. He brought sleep to both men and gods, and sometimes sent his sons Morpheus, Icelus, and Phantasus to appear in dreams. At the door of his abode grew poppies and other herbs which induce sleep (Hamilton, 1961). This book deals with these herbs and their subsequent imitations. Before launching into an examination of hypnotics, it might be well to comment briefly on the manner in which this was written, and to acknowledge the help of a number of individuals. My intention was that this be useful not only for the physician or scientist, but also for the student. Thus each chapter contains an introductory section which pro vides background material. Chapter 3, for instance, describes the general principles of drug absorption, distribution, and metabolism before dis cussing the pharmacologic properties of each hypnotic. In addition, each chapter concludes with a section which summarizes the main issues.