Psychophysiology of Sleep

Sleep is a complex behavior, neurophysiological, psychological, and neurochemical phenomenon, which shows striking phylogenetic and ontogenetic changes. Among its numerous and vital functions, research has identified energy conservation, brain waste clearance, immune response modulation, development, learning, cognition, optimal performance, recovery from disease, modulation of vigilance, and several other mental/psychological processes. This chapter provides a condensed overview of the normal and pathologi-cal human sleep, and of the main neurophysiological tool (polysomnography) that has been for decades the gold standard for its study. This chapter is intended as an introduction to this complex and fascinating topic, especially in the field of Psychophysiology, and provides a basis for needed future research combining the “physical” and “psychic” aspects of sleep, especially concerning the origin of sleep and its stages, as well as the psychophysiological characteristics of normal sleep and their changes occurring in sleep disorders.