matters of life

The living under influence: "rhythms & blues

The Tuesdays of the Université Populaire will resume this evening, Tuesday, October 20, 2015 at 7:00 pm, as part of the Cycle VIES QUESTIONS of the Living Festival, thereon "Living Under the Influence: Rhythms & Blues"with André Klarsfeld, biologist, professor at the ESPCI, author of "Les cloges du vivant" (Odile Jacob). A conference for the general public to better understand our biological clock, in order to better understand what we are. 
For this new cycle of meetings and debates, the Université Populaire du 2e offers you in five fun lectures to discover and participate in visions, ideas, points of view and initiatives that inaugurate the world of tomorrow from the perspective of the living.
Illustration: Golnaz Behrouznia
Taking into account the changes in the climate, which everyone has been observing in recent years, wherever they live on this planet, these meetings will attempt to question the life to come - our lives.
Are we vulnerable? Do we have the right techniques? Why should we be standardized? Is automation inexorable? Will we be able to adapt? Should we speed up or slow down?
Between concern and hope to change this threat: concrete questions and answers.
First conference: Tuesday, October 20, "Rhythms & blues" with André Klarsfeld

Many biological functions follow a 24-hour cycle, discreetly regulated by our internal clocks: the alternation between sleep and wakefulness, but also food intake, body temperature or hormonal secretions. However, modern life is increasingly disrupting these clocks...
Is the acceleration of our rhythms sustainable? Should we always accelerate or catch our breath? And what if the "Tempo of our bodies" was the key to avoiding illness and insomnia and to optimizing our memory and performance...? 
Biological clocks, which punctuate our lives without us being aware of it most of the time, are an essential dimension of the animal, plant and even microbial worlds. They facilitate adaptation to the immutable cycles of days and seasons, and explain seasonal depressions as well as the onset of the mating season in animals. It is this order, with its occasional or lasting upheavals, that André Klarsfeld has shown us in his book "Les cloges du vivant" published in 2009 by Odile Jacob.
The understanding of the functioning of the "master clock" has benefited from advances in molecular genetic tools to identify "clock genes" within many cells. « What remains to be understood is the language that this conductor uses with his musicians and how the latter carry out their function, writes André Klarsfeld. These two major areas of research could indeed have immense potential medical benefits. » 
His book ends with a chapter devoted to the past and future impact of chronobiology in the field of health with questions as pragmatic as those of jet lag, "morning" and "evening" subjects, problems of shift work, links between chronobiology and depression, summer and winter time.
André Klarsfeld is currently Professor at the École Supérieure de Physique et de Chimie Industrielles (ESPCI ParisTech) of the City of Paris, Neurobiology Laboratory (ESPCI/CNRS). He is a member of the Société francophone de chronobiologie. With Frédéric Revah, he wrote Biology of Death.

Out of sync. Why is it out of sync? Why? 
A healthy organism is one that is synchronized with environmental factors. Otherwise, the desynchronization of the internal clock is the cause of various health problems, some of which can be important and serious when the situation of desynchronization is chronic, such as in shift work and night work.
The internal clock, located in the suprachiasmatic nuclei of the anterior hypothalamus, is under the control of external factors (environmental factors, social life) and genetic factors. When the internal clock is no longer in phase with the environment, the organism is out of sync. The causes of this desynchronization are numerous and may be related to synchronizers that are in conflict with the internal clock (shift work, night work, trans-meridian flight), or to synchronizers that are ineffective (aging, certain psychiatric illnesses...), or to synchronizers that are poorly or not perceived (blindness), or to a lack of clock drive (circadian sleep disorders such as phase delay or phase advance syndromes), or to certain medications or drugs (lithium, propofol, alcohol...). Situations of desynchronization, especially if it is chronic, can lead to disorders of the body that can be serious. The resynchronization of the clock is achieved with the administration of melatonin or by exposing the patient to strong light.
Living organisms are subject to the 24-hour day-night cycles imposed by the rotation of the earth. They have developed a circadian clock that makes it possible to anticipate environmental changes in order to adapt physiology and behaviour to this cyclical environment . Clocks are present throughout the living world, including some prokaryotes (cyanobacteria), and show an astonishing similarity in the mechanisms that generate molecular oscillation. In the animal world, the conservation of clock genes is important and many of them play the same role in insects and mammals. 
The synchronization of the brain clocks with the day-night cycles is mainly achieved through changes in light and temperature. In the laboratory, flies synchronize within a day to a light-dark cycle shift of several hours.
Academy of Medicine Alert: Exposure to light at night can be harmful to health
The National Academy of Medicine alerts social actors (1)The Commission is also working with the European Commission, at all levels of prevention and decision-making (legislators, occupational physicians, employers, workers, etc.), on this new pollutant, exposure to light at night, and the urgent need to take concrete measures. 
Light is a key factor in the functioning of our internal clock. When the clock receives the message transmitted by light during the day, as is usually the case, the body is synchronized. On the other hand, when the clock is chronically exposed to light at night, the body is out of sync and suffers from various disorders, some of which can be serious (increased risk of sleep disorders, cardiovascular disorders, cancer, etc.).  
15 % of the active population is concerned: En 2012 in France, 15.4% of the working population (21.5% of men and 9.3% of women), i.e. 3.5 million people worked at night on a regular or occasional basis.
In industrialized countries, including France, about 75 % of the working population work atypical hours, i.e. outside normal working hours, typically from 8 a.m. to 5 p.m.. A retrospective Danish case-control study of 7565 women indicates that women working predominantly at night for more than six years have a significant increase of 70 % in the relative risk of breast cancer.
On the other hand, more and more teenagers are accumulating a sleep debt because of the time they spend in front of the screens, at the risk of developing fatigue, daytime sleepiness, but also metabolic abnormalities, neurocognitive disorders with a drop in school results, or mood disorders. A study by Cajochen et al. shows that light from the latest generation of LED screens, enriched in the blue spectrum, had a more powerful effect on the circadian system compared to fluorescent screens, and thus the potential to further reinforce the vicious circle of chronic sleep debt in adolescence. 
Location 2nd District Town Hall, 8, rue de la Banque, 75002 Paris, France
Registration is free but compulsory (there are still places left!)
(1) Dedicated session of 6 October 2015 : "Desynchronization of the internal clock and public health."  
References :
1- Y. Touitou, Pollution of the internal clock by light at night, a public health problem. 
2- CM. Schröder, Circadian Sleep Disorders in Adolescents: The Role of Multimedia. 
3- F. Rouyer. Clock genes: from drosophila to man 
3- Y. Touitou. Adolescent sleep misalignment and chronic jet lag, a matter of public health. J. Physiol. 2013, 323-326.

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