The book provides an overview of the entire field of sleep medicine, from the basics of sleep physiology to the diagnosis and treatment of specific sleep disorders. It offers a valuable introduction to the field of sleep medicine, but also serves as a reference work on all aspects of clinical practice, including diagnosis, differential diagnosis and treatment of all relevant sleep disorders in children and adults. It starts by presenting sleep physiology and the classification of sleep disorders, and explains in detail all the relevant diagnostic measures in the field. Based on these introductory chapters, it discusses the relevant sleep disorders, including insomnia, sleep-related breathing disorders, hypersomnia, sleep-wake-rhythm disorders, parasomnia, sleep related movement disorders, and secondary sleep disorders, as well as various isolated symptoms. In addition, an entire chapter is dedicated to sleep disorders in children. Drawing on the long-time experience of five board-certified sleep physicians with different professional backgrounds, the book reflects the interdisciplinary nature of sleep medicine. It includes the current international classification systems as well as scoring rules and clinical guidelines. It is intended for physicians and therapists from various specialities, including internal medicine (e.g. pulmonology and cardiology), psychology, psychiatry, neurology, paediatrics, otorhinolaryngology and general medicine who are interested in sleep medicine. It also serves as a textbook in these specialties. To optimize its clinical value, a uniform structure is used for the various chapters, including practical tips, comprehension questions and clinical case presentations.