The circadian rhythm is the mechanism through which the body regulates between day and night. From it, physiological processes are adjusted so that the body can carry out its activities, such as waking up, feeling hungry, feeling sleepy, etc. The 24-hour period, that is, a full day, is what drives the circadian rhythm. It is our "clock."
Light during the day and absence of it during the night influence our biological clock, which regulates activities for each period of the day, determining the behaviors of the body.
The circadian rhythm interferes with body temperature, hormone production and release, and appetite. That is, its influence on metabolism is direct.
During the day, cortisol helps to wake up, and insulin assists in the processes of using glucose obtained from food. During the night, melatonin prepares the body for sleep. Because of this, our choices of schedules and habits can positively or negatively influence hormonal balance. In other words, attention to this is essential so that hormonal imbalance does not trigger any illness.
Have you noticed that there are "morning people" and "night owls"? Inside the brain, there is an area responsible for the command that defines our preference for day or night. That is, the "choice" for moments to perform daily activities is cerebral. This means that the circadian rhythm, to some extent, is very personal. And the name given to this is chronotype, the tendency of each individual's needs during periods of the day.
Diurnal or nocturnal habits interfere with all the habits and activities that we carry out throughout each day, especially because of light. Genetics is already a recognized factor as a condition for determining individual chronotype. It is not determinant, but it influences predisposition.
Chronotype is directly associated with metabolism, and it is essential to understand how the body functions based on individual genetics. Knowing your own metabolism and the times when you produce more, rest more deeply, feel more or less hungry, is a huge advantage when the goal is quality of life, balance, and a healthier life. The biological clock has everything to do with habits.