n. the internal mechanism which controls the rhythm of activities in a living organism. Referred to as biological rhythm or biorhythm, it involves a pattern of activity and rest within a 24-hour period. This behavior pattern occurs even without external cues. Also called internal clock.

BIOLOGICAL CLOCK: "The human biological clock is a hypothalamic function that enables an individual to alternate between activity and rest within a 24-hour period."
Cite this page: N., Pam M.S., "BIOLOGICAL CLOCK," in, April 7, 2013, (accessed April 19, 2021).