Normal Sleep and Circadian Processes

Nancy A. Collop, Rachel E. Salas, Michael Delayo, Charlene Gamaldo

Research output: Contribution to journalReview articlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)449-460
Number of pages12
JournalCritical Care Clinics
Issue number3
StatePublished - Jul 1 2008

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


Dive into the research topics of 'Normal Sleep and Circadian Processes'. Together they form a unique fingerprint.

Cite this