Many holidaymakers will discover the joys of jet lag. Positive in the east-west direction. Painful in the opposite direction. How better to live it?
All our organs, all our vital functions have a rhythm whose frequency is different. Indeed, a team of Inserm researchers, led by Howard Cooper (Inserm Unit 1208 "stem cell and brain institute"), recently demonstrated in a study that organs do not function in the same way depending on the time of the day.
It is not a clock that manages our lives but rather a set of watches obeying an hourly oscillation, daily, weekly, monthly, or even annual for certain functions. All essential functions of the body are synchronized with time by the circadian clock of the body. A small area at the bottom of the brain near the mouth reminds us to wake up and go to bed at regular times each day. This internal clock is scientifically called the suprachiasmatic nucleus or NSC. When this system is disrupted, by staggered work schedules or a trip to another continent, for example, the 20,000 nerve cells in this area are struggling to adjust the body to a new rhythm.
We do not know the name of the great watchmaker, but that of one of his assistants, melatonin. Melatonin is a natural hormone secreted by the brain when the light goes down to tell it is time to go to sleep. It allows the body to orient itself in time, thanks in particular to the light / dark alternation that triggers its secretion.
The protective effects of melatonin
In the treatment of breast cancer, for example, it has been found that its blood level in American women is lower than that of Japanese women, who develop far fewer breast cancers. The flight attendants - who, because of their travels, have anarchic secretions of melatonin and thus a lower rate - also have twice as many cancers of this type as the women who stay on Earth. All the major biological functions are directly or indirectly controlled by this system: the hormonal secretions, but also the functioning of the heart, digestion, immunity, and of course the brain.
How to better live the jet lag?
It is quite possible to gradually shift your biological clock (your pace and your sleep cycles) a few days before departure, so as not to impose it brutally on your body. Go forward, or back (depending on your destination) the time of lunch, dinner and bedtime. You can also shift the time of your watch, so that it sticks to your new pace. If you are on treatment, talk to your doctor.
During the flight, remember to hydrate regularly, but avoid sodas, tea or coffee. Eat light. Regularly stretch your legs. If your flight is long, opt for compression stockings to facilitate your blood circulation. If you land very early in the morning, rest, but make the most of the natural light of the day. For example, do not go to bed at 5am to get up at 2pm.
American biologists have managed to develop a tool against jet lag on mice by activating a subset of neurons involved in setting daily rhythms. The results were published Thursday, July 12 in the scientific journal Neuron.
For more information: Neurological sleep disorders
"Neurological sleep disorders": a very practical program concerning the exercise of all doctors. - Restless leg syndrome, sleepwalkers and night terrors, elderly people screaming and falling from their beds, hypersomnia, sleep apnea, not forgetting two high-profile subjects: the influence of screens, whatever they are (TV, computer or smartphone) about the quality of sleep, and this "exploding head syndrome" that made headlines last week. Our guest is a great specialist in these unrecognized but widespread sleep disorders! Isabelle Arnulf is indeed professor and head of service of exploration of the sleep disorders, with the Pitié-Salpêtrière in Paris.
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