Introduction to Sleep and Circadian Disorders offers an integrated framework for understanding how sleep biology and circadian regulation interact to influence human health, behavior, and disease across the lifespan. The book begins by outlining the fundamental mechanisms that govern sleep-wake regulation, including the dynamics of rapid eye movement (REM) and non-rapid eye movement (non-REM) sleep, sleep homeostasis, and the circadian timing system. These core processes are presented as interconnected systems that coordinate physiology with the external environment and help maintain cognitive performance, mood stability, metabolic balance, cardiovascular function, and brain health.The text guides readers through essential diagnostic approaches used in sleep medicine, including polysomnography (PSG), home sleep apnea testing (HSAT), and actigraphy, emphasizing how these tools support the evaluation of sleep quality, circadian alignment, sleep fragmentation, and sleep-disordered breathing. The book provides structured introductions to key conditions such as insomnia, obstructive sleep apnea, hypersomnia, circadian rhythm sleep-wake disorders, and disorders associated with insufficient or irregular sleep. Evidence-based treatment principles are presented where clinically relevant, grounding management strategies in physiology and patient-centered practice.A central theme of the book is the broad impact of sleep and circadian disruption on health. Chapters explore connections to chronic disease, cognition, neurodegeneration, mental health, and aging, illustrating how behavioral, biological, and environmental factors interact to shape long-term outcomes. The book also addresses developmental considerations, describing age-related changes from infancy through older adulthood. It equips readers with the conceptual tools needed to interpret sleep-wake patterns, recognize common disturbances, and understand the role of sleep and circadian health in promoting wellbeing throughout life.
