What is the name of the daily cycle?

The biological process or daily cycle that keeps most organisms functioning on a 24-hour schedule is called a circadian rhythm. Circadian rhythms are most closely studied in humans, but they also occur in nonhuman organisms, including fungi, plants and even bacteria.

Circadian rhythms are characterized by three main aspects: They last approximately 24 hours without external input, or endogenously; they can be reset, such as when traveling across time zones; and they compensate for changing temperatures without altering the 24-hour cycle. These three characteristics allow organisms to rely on circadian rhythms for regulating sleeping and eating patterns that are essential to survival.