The functioning of the human body varies throughout the hours of the day, in what seems like a biological clock that is deeply ingrained in it, and more information is available about it, to the point that some doctors resort to using it as a effective tool. against a series of diseases.
“There is a set of clocks in the body to improve its performance: this is called the circadian system,” says Claude Grunvier, a researcher at the National Institute for Health and Medical Research in France.
The existence of these clocks has been known for a long time. Over the last several decades, research has shown that limb activity varies at different times of the day; The intestines, liver, and heart tend to work harder at certain times, regardless of the timing of meals or physical activity.
At the same time, research in animals and later in humans has shown that this rhythm was not just a response to the outside world, like the alternation of day and night. It turns out that E registers in our cells, starting with neurons in the brain.
But while the research has advanced enough for three researchers in the field to win the Nobel Prize in Medicine in 2017, it has accelerated further in recent years, in particular to show how this clock exists in cells all over the world. the body.
“There are clocks in the liver, heart, lung, kidney, retina…” explains Grunvier.
It turns out that day by day these hours have very different effects. A study led by Claude Grunvier, the results of which were published this summer in the journal Brain, indicates that pain perception varies in intensity over a 24-hour period.
During this work, twelve men were isolated from all external stimulation for about a day and a half, and every two hours they were exposed to a heated probe. Their pain threshold varied systematically over time.
The researcher believes that this is a crucial step towards a better understanding of pain, and points out that one day we will be able to better manage it by taking into account its fluctuations during the day.
The research is part of a broader school in this sense. To some researchers and doctors, these rhythms are well known enough to be used against many diseases.
This is known as “chronotherapy” or “daily medicine.” For its promoters, the applications will be very diverse, from oncology to cardiology and neuroscience.
In Alzheimer’s disease or Parkinson’s disease, for example, the circadian rhythm is previously known. But it is now known that this disorder often precedes symptoms and therefore may be a preventable cause rather than an effect.
Overall, however, “we are still challenged to apply this knowledge about the role of circadian clocks in the medical world,” researchers Ravi Allada and Joseph Bass warned last year, writing in a scientific paper in the New England Journal of Medicine.
Therefore, there is a lack of techniques that allow the clinician to easily diagnose the alteration of the circadian clock and, therefore, advise the patient in a way aimed at changing the rhythm of their life to avoid health problems.
There are other ways it could clash with reality, such as the idea Claude Gronvier has fervently advocated of taking the time of day into account when administering chemotherapy to a cancer patient.
“Let’s imagine that experience shows that the treatment must be carried out between 10:00 p.m. and 8:00 a.m.: this will lead to small organizational problems,” oncologist Pierre Santini told AFP.
And he continues: “We already live in a world, at least in France, where the health system is on the verge of collapse”, “You have to be very convincing to fundamentally change an organization where there is enormous pressure in the first place. .”
Therefore, not only is it necessary to test the effect, but it also has a “significant impact on the response to treatment and patient survival,” concludes Santigny, who believes that studies in this area are currently insufficient.