Book excerpt: The orexin system, discovered in 1998, has emerged as a crucial player in regulating the sleep and wake balance inside our brain. This discovery has sparked a burst of novel and dynamic research on the physiology and pathology of sleep. The Orexin System: Basic Science and Role in Sleep Pathology honors this research and the authors share their ideas and perspectives on the novel developments within the field. The book examines the intricate role of the orexin system in regulating sleep and wake, and its interaction with other wake-regulating systems. The orexin system is dissected at the cellular and molecular level to explore the diversity of the orexin-producing neurons, their projections, and their signaling pathways. Additionally, the book discusses the diseases which are associated with a dysfunctional orexin system, such as narcolepsy, insomnia, substance abuse, and Alzheimer’s disease, and explores the new potential therapeutic applications derived from the burst of research around this fascinating system. This publication is essential reading for neurobiologists, neurologists, psychopharmacologists, sleep researchers, and other researchers and clinical scientists interested in sleep, sleep research, insomnia, and medicine in general.