“We have two types of biological clocks in the brain,” explains neuropsychiatrist Marc Schwob, author Rhythms of the body (Odile Jacob 2007). The first, sensitive to natural rhythms, such as the day-night alternation, determine the cycles of hormonal secretions, cell regeneration and, in cascade, the activity of the organs. The second, located in the cortex, the intelligent part of the brain, allows us to control our time in accordance with social synchronizers (alarm clock, business lunch, TV news…). However, the latter influence us more than the natural synchronizers which are the length of the days or the variations in temperature. We therefore shake up our biological tempo to match that of modern life. Problem: our body cannot keep up with it. “Nor to adapt to it in a healthy way,” adds James H. Bendayan, researcher in the medical genomics of human biological rhythms. Not respecting our natural rhythm has biological consequences that the body cannot bear. ”
“We have thus turned the periods of productivity upside down,” notes Marc Schwob. Rather than working in the summer and resting in the winter, like our ancestors, we do the opposite. »Fixed at the time of harvest and harvest, the summer holidays have become, with the decline in agricultural activity, times of idleness. Result: in winter, we work too much and too late in relation to the sun’s cycle. And, to see our friends or hang out in front of the TV, we go to bed two or three hours apart.
As a result of these changes, “the secretions of melatonin and serotonin, hormones regulating sleep rhythms, antioxidants, are shifted, affecting the immune system and not allowing cells to repair themselves, deplores James H. Bendayan. Disastrous for the body, this desynchronization is implicated in the development of certain pathologies – obesity, diabetes, mental illnesses, cancer… ”. In December 2007, the Lyon International Cancer Research Center even declared night work to be probably carcinogenic. Installed, this shift would also modify the expression of the genes of the cerebral and peripheral central biological clock in the tissues and the organs, to the point of making it adopt an anarchic behavior in the protection and the integrity of our genome. The machine is racing. James H. Bendayan adds that “these epigenetic alterations [dues à l’impact de l’environnement sur les gènes, ndlr] are probably also transmitted from the mother to the fetus when, while pregnant, she “carves” the cells of her offspring. Inheriting these desynchronizations, the child will be more vulnerable in the future ”.
A body on constant alert
Another disruption of our modern life: immediacy. Continuous access to information, requests by e-mail, text message, telephone… The body is under constant tension. “The alert system, beneficial for fleeing or for self-defense, is never at rest,” emphasizes Marc Schwob. Stress hormones – cortisol, catecholamine and adrenaline – are secreted more and more often, making us feel overwhelmed. »A feeling accentuated by a permanent hubbub: noise from the street in the morning, from the office during the day, revelers or garbage collectors at night … Overwhelmed by our social life, we no longer take the time to dream, to yawn, to relax , “What the body needs every ninety minutes,” recalls the neuropsychiatrist. Feeling intense fatigue, great difficulty concentrating, nervousness, tremors, and having sweaty hands are all signs that can indicate desynchronization. “Stimulated too often, weakened by a sleep debt, the parasympathetic nervous system no longer controls the sympathetic, which regulates anxiety and pain,” continues Marc Schwob.
Hence, to limit the damage, the importance of activities that stimulate pleasure hormones (endorphins) and neutralize those of stress: playing sports, love, relaxing, laughing, looking at the horizon … occupations often reserved for vacation time. Moreover, “continued for more than eight days, ideally two weeks, they make it possible to resynchronize”, adds the neuropsychiatrist. On condition, two days before the start of the school year, to get back to office hours so as not to undergo a new change of tempo. The ideal being, of course, to harmonize every day its social rhythm with its biological rhythm. But, for that, it is still necessary to succeed in decelerating …
Three keys to resynchronize
1. Take the time to wake up
The body needs time to wake up from REM sleep, a phase of regeneration of nerve pathways and cell repair. The morning light gives him the signal to increase the secretion of cortisol, which prepares him to face the aggressions of the day. “In the morning, the fall in the rate of melatonin, a sleep hormone, also induces us to wake up. In addition, it is better to replace the stress of a ringing tone, which weakens our cortisol stock, with a dawn simulator, ”advises neuropsychiatrist Marc Schwob.
2. Rebalance your meals
An English breakfast (cereals, dairy products, proteins) meets the requirements of the food clock. It corrects the hypoglycemia of the night by the absorption of sugars (slow and fast) and ensures reserves for the activities to come. “In order to respect the cycle of insulin and digestive juices, lunch should be simpler (lean meat and vegetables),” says Marc Schwob. Same menu at dinner, which thus provides the body with sufficient carbohydrate content to repair itself during sleep. Some nuts, hazelnuts or almonds, rich in magnesium, also give the brain the signal to secrete melatonin, therefore to prepare for sleep.
3. Go to bed two hours after the sun
That’s the advice of James H. Bendayan, a researcher in the medical genomics of human biological rhythms. When the daylight begins to fade, our internal clocks send signals to the body of fatigue (drop in temperature, attention, yawning, etc.) that should be respected in order not to be out of phase. Especially since the sleep before midnight is of better quality. As long as you are in complete darkness and silence.