Sleep Disorders: Circadian Rhythm Disorders
Circadian rhythm disorders are disruptions in a persons circadian rhythm -- a name given to the "internal body clock" that regulates the (approximately) 24-hour cycle of biological processes in animals and plants. The term circadian comes from Latin words that literally mean around the day. There are patterns of brain wave activity, hormone production, cell regeneration, and other biological activities linked to this 24-hour cycle.
The circadian "clock" in humans is located mainly in the suprachiasmatic nucleus (SCN), which is a group of cells located in the hypothalamus (a portion of the brain). Circadian rhythms are important in determining human sleeping patterns.
What Causes Circadian Rhythm Disorders?
Circadian rhythm disorders can be caused by many factors, including:
Common Circadian Rhythm Disorders
How Are Circadian Rhythm Disorders Treated?
Circadian rhythm disorders are treated based on the kind of disorder that is present. The goal of treatment is to fit a persons sleep pattern into a schedule that can allow the person to meet the demands of a desired lifestyle. Therapy usually combines proper sleep hygiene techniques and external stimulus therapy such as bright light therapy or chronotherapy. Chronotherapy is a behavioral technique in which the bedtime is systematically adjusted. Bright-light therapy is designed to reset a persons circadian rhythm to a desired pattern. When combined, these therapies may produce significant results in people with circadian rhythm disorders.
Reviewed by The Sleep Medicine Center at The Cleveland Clinic.
Edited by Michael J. Breus, PhD, WebMD, September 2004.
Portions of this page © The Cleveland Clinic 2000-2005
Last Editorial Review: 6/20/2005
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