The body is essentially a collection of clocks. ~ Indian biologist Satchindananda Panda
Every single cell in our body has its own molecular clock, including all the machinery required for the body to know what time it is. ~ American neurobiologist Andrew Gaudet
All organisms coordinate their biology and behavior according to an endogenous circadian clock which is based upon Earth’s daily rotation. The circadian clock is an evolutionarily highly conserved physiological timing mechanism.
One way that bacteria manage antibiotic tolerance is by slowing their biological clock, allowing dormancy during dosing, thereby letting toxicity flow past without taking it in.
The many biological processes that oscillate via the circadian clock are under sway of circadian rhythm. All manner of functions are timed, including the wake/sleep cycle and even blood production. The common clock-winder is exposure to light.