What are circadian rhythms?
Circadian rhythms are physical, mental and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in an organism's environment. They are found in most living things, including animals, plants and many tiny microbes. The study of circadian rhythms is called chronobiology.
Are circadian rhythms the same thing as biological clocks?
No, but they are related. Our biological clocks drive our circadian rhythms.
What are biological clocks?
The biological clocks that control circadian rhythms are groupings of interacting molecules in cells throughout the body. A "master clock" in the brain coordinates all the body clocks so that they are in synch.
What is the master clock?
The "master clock" that controls circadian rhythms consists of a group of nerve cells in the brain called the suprachiasmatic nucleus, or SCN. The SCN contains about 20,000 nerve cells and is located in the hypothalamus, an area of the brain just above where the optic nerves from the eyes cross.
Source: NIGMS (NIH)1
• • •
Biological Clocks: The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioral phenomena.2
Read about these related anatomy topics:
Read about these related symptoms:
- Behavioral symptoms: Summary:
An abnormality of mental functioning including various affective, behavioural, cognitive and perceptual abnormalities.3,4
... More on Behavioral symptoms »
Related Symptom Topics
Read more about these related symptoms:More »
• • •
- Source: NIGMS (NIH): nigms.nih.gov/ education/ pages/ Factsheet_CircadianRhythms.aspx
- Source: MeSH (U.S. National Library of Medicine)
- [from HPO]
- Source: GTR (NCBI/NIH): ncbi.nlm.nih.gov/ gtr/ conditions/ CN000665/
• • •
Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.