Normal sleep and circadian processes.
The onset of sleep is associated with a variety of changes in both behavioral and physiologic states. Sleep is not a uniform state either: it has different stages that affect different areas of the brain and body. Nonrapid eye movement sleep stages are as different from rapid eye movement sleep as is wakefulness. Circadian rhythms of physiologic systems also impact wake, sleep, sleepiness, and alertness. There are characteristic changes in both sleep patterns and circadian rhythm that occur with aging. The cardiovascular, respiratory, endocrine and gastrointestinal systems also undergo changes with sleep onset. This article reviews the aspects of normal sleep, physiologic changes that occur in the human body with sleep, and how sleep changes over the lifespan.
Collop
Nancy A
NA
Division of Pulmonary/Critical Care Medicine, 1830 East Monument Street, Room 555, Johns Hopkins University, Baltimore, MD 21205, USA. ncollop1@jhmi.edu
Salas
Rachel E
RE
Delayo
Michael
M
Gamaldo
Charlene
C
D000375:Aging; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D012894:Sleep Stages / Q000502:physiology*