Circadian Rhythm is a 24 hour cycle in the physiological,
behavioral or biochemical processes of living beings, including
humans, animals, plants and micro-organisms.
Although circadian rhythms are endogenous to the living being,
they are affected by external triggers, such as light. To classify
a rhythm as circadian, it should persist in the absence of external
cues, should persist over a range of temperatures, and should be
possible to adjust to local time.
The impact of circadian rhythm can be seen in the patterns of a
variety of activities such as eating, sleeping, brain activity,
temperature, hormone production and cell regeneration.
The importance of circadian rhythm in psychology stems from the
fact that disturbances in this rhythm can lead to disorders such as
Delayed Sleep Phase Syndrome (DSPS), fatigue, disorientation and
insomnia. Other disorders such as bipolar disorder and sleep
disorders are associated with irregular function of the circadian
rhythm.