All humans have a circadian rhythm. Specifically this is your 24 hour daily cycle.
Organisms from bacteria with a mere single cells, to plants, to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation and in part specifically due to the light and dark, weather, and tides, that our Earth’s cycle produces.
These internal circadian clocks that regulate many aspects of behavior, such as our sleep cycles, physiology and metabolism. Our physiology then adapts and can both anticipate and and synchronize internal time-keeping to changes in the cyclical environment.
Some of us are night creatures, some are set to morning rising. Some of us are more variable like the lowly mosquito that is active both at dawn and dusk.
Our modern technology, with light bulbs, and heating and cooling of our environment has radically altered rhythms we would naturally follow.
Resulting consequences can be weight gain, mood alterations, menstrual cycle changes, hormonal changes, and much more far reaching consequences. If you have health concerns or issues, or just want to live your healthiest life, you can reset your biological clock.
For many of us, we’ve live with technology so long, it’s not clear what our real ‘nature’ is.
Of course changing your sleep patterns will help you reset, changing when you work out, and when you hydrate can all work to stabilize your circadian rhythms. Specifically altering your daily rhythm by changing when you eat, and duration of fasts can be one relatively simple way to reset your biological clock.