Sleep Architecture and Physiology

Sleep architecture is organized into nonrapid eye movement (Stages N1, N2, and N3) and rapid eye movement sleep that rotate through a given sleep period in discrete cycles. Each stage has specific characteristics including different electroencephalography waveforms, muscle tone, and eye movements. This chapter reviews those features and specific physiological characteristics of different stages of sleep. It also reviews how sleep architecture varies across lifespan and the importance of the knowledge of normal architecture to understand many sleep disorders. In addition, understanding physiology of normal sleep in different stages and their role in the pathophysiology of various sleep disorders are discussed. Physiological changes that occur during sleep are usually well tolerated in healthy people, but these changes may adversely affect people with vulnerable organ systems.