Circadian rhythms, sleep, and sleep disorders covers the topic in two sections focusing on basic science and clinical application. In the basic section, new developments and research findings focusing on basic circadian rhythm and sleep physiology in animals and humans is highlighted. The chapters are written in short mini-review formats in order to concisely describe the fundamentals, and current hot topics. The basic part starts with a chapter on the fundamentals and new discoveries on oscillating circuitries in the sleeping rodent and human brain. This sets the stage for chap 2, focusing on circadian and homeostatic aspects of human sleep regulation. Chap 3 extends these aspects to human cognition. The next chapter reports on visual and non-visual effects of light on human behavior, particularly endocrine and electrophysiological correlates. Chap 5 covers chronic sleep restriction effects on functional connectivity states. The last two chapters (6 and 7) give a broad overview on sleep modeling across physiological levels, with a focus on a quantitative model of sleep-wake dynamics based on the physiology of the brainstem ascending arousal system. The clinical section of the book describes the circadian rhythm sleep-wake disorders, from epidemiology to clinical picture and treatment. Disorders covered include delayed and advanced sleep phase syndrome, Irregular sleep-wake rhythm disorder, shift work disorder, restless legs syndrome, nocturnal eating syndrome, narcolepsy, and sleep apnea. Pharmacological and non-pharmacological treatments of insomnia are explored, as well as the role of sleep-wake modulation in the pathogenesis and clinical profile of neurodegenerative disorders, such as Parkinson’s disease and Alzheimer’s disease.