If our biological clock goes out of whack, we waste our health. And we stay tired all day.

Following and supporting natural rhythms is a guarantee of well-being. And of excellent sleep during the right hours.

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Biological clock

We have a time for everything. For eating and sleeping, for exercising or concentrating on work and study, when the temperature rises or falls. We are equipped with a biological clock , whose rhythm is regulated by the alternation of light and dark, which we must respect to maintain good physical and psychological balance. Let's take an example. The biological clock predicts that the body is not structured to eat at night, when rest is instead supposed to be. So if at midnight we eat the same pizza or pasta dish we could have had at noon, the metabolism will be very different and slower. The result is that we gain more weight.

BIOLOGICAL CLOCK

The biological clock regulates the body's metabolic processes by controlling the circadian rhythm . It is located in the hypothalamus, where a group of cells called the suprachiasmatic nucleus (SCN) is able, thanks to a highly complex mechanism, to synchronize all the body's biological activities. This nucleus operates on a 24-hour cycle, adapting the body's biological rhythms to external day/night rhythms. The biological clock is regulated by light and darkness: light blocks melatonin, the hormone that regulates sleep, keeping us awake. The opposite happens with darkness.

But is everyone's biological clock the same? The answer is no, because it varies depending on individual characteristics. It's no coincidence that some people are more active in the morning, while others are more active at night. However, regardless of these differences, respecting the circadian rhythms dictated by the biological clock is beneficial to your health. This is why it's important to prioritize certain activities over others depending on the time of day.

HOW THE BIOLOGICAL CLOCK WORKS

Our biological clock is regulated by the suprachiasmatic nucleus of cells , which receives information about external light and adapts internal biological rhythms to the external day/night cycle. This information influences the clocks of various organs and, therefore, must be carefully considered. In fact, there are activities, depending on the time of day, that are suited to certain time slots and others that should be avoided, following the clock.

In the morning, for example, when cortisol increases and melatonin decreases, the body needs to wake up slowly because it is not yet fully active at this stage. From 9:00 a.m. to 12:00 p.m., cortisol increases further and the body becomes fully active, allowing us to carry out the most demanding activities of the day. After lunch (especially if heavy), digestion causes some drowsiness. In the afternoon, up until 6:00 p.m., the heart and lungs become particularly efficient, body temperature rises, and muscles are more toned. This is the recommended phase for exercise.

As evening approaches, it's best to avoid heavy dinners because the intestines and liver tend to digest both fats and sugars poorly. Melatonin, which helps promote sleep, arrives at night; this isn't the ideal time for sports or activities that require concentration, or even for eating. Melatonin levels increase progressively throughout the night, allowing us to reach a state of total relaxation. At the same time, our body temperature gradually drops as the body's energy is used elsewhere, for example, to regenerate certain cells.

CIRCADIAN RHYTHMS

The circadian rhythm is the system that dictates the body's internal variations over the course of a 24-hour period . It depends on both external stimuli, such as the alternation of light and darkness, and genetic characteristics. It appears that we are genetically wired to follow a specific circadian rhythm that varies from person to person. Sixty percent of us have a sleep-wake cycle that roughly coincides with the external light-dark cycle, 30% have a shifted circadian rhythm, and 10% have an advanced circadian rhythm.

Biological clock out of whack: what's happening?

Your biological clock gets thrown off when your circadian rhythm isn't respected or if your rhythms and habits are too irregular . This often happens, for example, in business travelers who move across several time zones in a short time—the infamous jet lag. However, jet lag can also occur in everyday life, especially during the transition from weekends to Mondays. We sleep longer on weekends than on Mondays, the day we return to work, and the time difference can throw your biological clock off, especially if you wake up at a darker time each week. This shift increases the risk of obesity and smoking.

The biological clock can also be affected by other circumstances. For example, those in the 30% of people with a shifted circadian rhythm should prefer a job that respects their chronotype, starting late in the morning and finishing late at night. But we often find ourselves forced to adapt our genetic rhythms to our professional ones, rather than the other way around.

Another factor that disrupts the biological clock is sleep deprivation , which is closely linked to increased risks of high blood pressure (more common among those who work night shifts), breast cancer, obesity, stroke, type 2 diabetes, and heart attacks. Even failing to respect one's circadian rhythm can increase the risk of certain cancers, and it's no coincidence that certain anticancer drugs are administered at specific times, according to a person's biological clock, making them more effective.

How can you fix this? Simply maintain regular rhythms and habits, such as going to bed at the same time every night and for a sufficient number of hours. And do activities suited to different times of the day.

READ ALSO: How to sleep better and avoid wasting your health

TESTS FOR THE BIOLOGICAL CLOCK

There are several tests for our biological clock , from one that tells us whether we're "night owls" or "larks" based on our habits, to a blood test that determines whether our biological clock is out of sync. The test in question, called "TimeSignature," is the result of studies by biologists at Northwestern University Feinberg School of Medicine in Chicago, published in the Proceedings of the National Academy of Sciences.

The test compares the genetic profile of 40 biological markers, identified by researchers using a machine learning algorithm, through two blood samples, and can be performed at any time.

The owl-lark test was used by Russian scientists to identify the most common chronotypes among people. Analyzing the results, they identified a group of "owls," people with a forward-shifted circadian cycle; a group of "larks," people with an early-shifted circadian cycle; and two other chronotypes corresponding to a group of people who are very active both in the morning and evening, and a group who are tired throughout the day.

LOTS OF TIPS FOR STAYING HEALTHY:

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