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.
Circadian
rhythms are produced by natural factors within the body, but they are also
affected by signals from the environment. Light is the main cue influencing
circadian rhythms, turning on or turning off genes that control an organism's
internal clocks.
Circadian
rhythms can influence sleep-wake cycles, hormone release, body temperature and
other important bodily functions. They have been linked to various sleep
disorders, such as insomnia. Abnormal circadian rhythms have also been
associated with obesity, diabetes, depression, bipolar disorder and seasonal
affective disorder.
Source:
National Institute of General Medical Sciences
