You searched for: “circadian rhythm
circadian rhythm
The regular recurrence, in cycles of about 24 hours, of biological processes or activities; such as, sensitivity to drugs and stimuli, hormone secretion, sleeping, feeding, etc.

This rhythm seems to be set by a "biological clock" which seems to be set by recurring daylight and darkness.

This entry is located in the following unit: rhythm-, rhythmo- + (page 2)