Circadian rhythm
These cycles are also called circadian clocks. The word "circadian" comes from the Latin circa, "around", and diem or dies, "day", meaning "about a day".  Biological time-keeping rhythms include daily, tidal, weekly, seasonal, and annual rhythms. However, most of these rhythms repeat once a day, so they are called circadian  from the Latin circa (about) dies (a day).