Historical Perspective In 1842, in a paper entitled "Further Development of a General Law of Vital Periodicity," which was part of a series of seven Lancet papers on periodicities in health and disease, Thomas Laycock wrote: "As everything finite must have a period within which its existence is circumscribed, so every period so circumscribing the finite, being a measure of time, must be divisible into lesser periods. But it has always been found easier to reason from generals to particulars than to ascend from particulars to generals, especially in questions in volving the phenomena of life" (p. 423). From a historical perspec tive, Laycock's insight indeed anticipated the progress of chronobio logic research. In spite of the abundant evidence pointing at the existence of short-term rhythms with periodicities much shorter than 24 hours, termed "ultradian" rhythms after Halberg (1964), it has gen erally been found much easier to investigate circadian rather than uI tradian rhythms. In m st cases, ultradian rhythms have been ignored, or dismissed as insignificant phenomena, even in cases where they could be easily "eyeballed" in the data. Laycock himself believed that the most basic periodicity in vital phenomena was 12 hours. Short-term fluctuations in the levels of certain behaviors, which could not be accounted for by external stimulation or by internal stimuli, have been known to ethologists and other observers of animal behavior for many years."

An authority in sleep research tells us everything we need to know about sleep apnea—its history, symptoms, risks, and treatment. An engaging book that is a “must read” for every snorer. People with severe sleep apnea may struggle for breath all through the night, not breathing for as long as ninety seconds at a time during their sleep. This syndrome, which affects at least four percent of men and two percent of women, can cause daytime fatigue, traffic and work accidents, deteriorating cognitive abilities, and cardiovascular problems. Yet until now there has been no accessible discussion of the history, physiology, and risk factors of sleep apnea. In this book Peretz Lavie, an expert in sleep research, tells the complete story of sleep apnea for the first time.

Why do we sleep? How much sleep do we really need? What causes sleep apnea, narcolepsy, and insomnia-and what can be done about these sleep disorders? Why do older people have more trouble sleeping than young people? We have all puzzled over-or been plagued by-the mysteries of sleep. Now a leading researcher on sleep provides an engaging and informative introduction to the subject that answers many of our questions. Peretz Lavie surveys the entire field of sleep research and sleep medicine-from the structure of sleep stages and the brain centers involved in sleep regulation to the reasons for and significance of dreams, the importance of sleep in maintaining good health, and the function of biological rhythms-interweaving facts with fascinating case histories, anecdotes, and personal reflections. We learn, for example, about: *development of sleep patterns from infancy to adulthood and in the aged; *the wide variety of sleep habits in animals; *dreams of Holocaust survivors; *sleep under the threat of Scud missile attacks; *how melatonin influences sleep; *the story of the "Acrobat's Leap" sleep-deprivation experiments in the Israeli army; *how to treat insomnia; *what to do with a baby who refuses to go to sleep; and much more. Originally published in Hebrew to great acclaim, this book will enlighten and entertain everyone interested in how and why we sleep.

Recent years have seen a rapid evolvement of sleep medicine as a new medical subspecialty. It is estimated that at least 30% of the adult population suffer at least once from some sort of sleep disturbance. Patients with sleep disorders are frequently among the most difficult to treat and account for a high percentage of absenteeism in the workplace. Furthermore, recent evidence indicates that sleep apnoea can be a major underlying factor of cardiovascular disease. This authoritative handbook covers the whole area of sleep, from the history of sleep medicine to the pathophysiology of sleep disorders, effective treatment and long-term management of the problem. The Sleep Disorders Handbook has been written for those working in specialist clinics as well as GPs, internists and non specialists. The editors have developed strategies for the management and agressive treatment of sleep disorders which are now used worldwide and which are clearly presented here. Enhanced by an entertaining selection of literary quotations on the subject of sleep and sleeplessness, this unique book will provide practical and much needed support in this new area of medicine.