On the night of Saturday to Sunday October 30, you will have to move the hands of your watch back one hour: at 3 am it will be 2 am. What are the effects of this time change on our circadian rhythm? How does this impact our health? Answers.
- On the night of October 29 to 30, 2022, we will switch to winter time: at 3 a.m. it will be 2 a.m.
- The time change is more difficult to manage for young children, teenagers, the elderly, night workers and people with sleep disorders.
- Summer time or winter time? The majority of chronobiologists (specialists in the biological rhythm of the organism), lean towards winter time because it would allow the body to have the necessary dose of light when waking up, and this, all year round. .
It’s a habit established more than 40 years ago, in 1976: in the spring we switch to summer time and have to increment the clock by an additional hour, and in the fall it’s reverse, we switch to winter time and move time back one hour. The origin of this idea? A compelling need to save energy by synchronizing sunshine duration with daily activities. If even today, the “Pros” and the “Cons” debate the usefulness of such a system, the scientific literature shows that the change of time does indeed have significant consequences on our health. .
Chronobiology: the time change impacts our circadian rhythm
The circadian rhythm, or “biological clock”, is the body’s internal clock. Like an orchestra conductor, it regulates certain physiological processes, such as sleep and food, over a 24-hour cycle. Its synchronization is mainly done through light, and disturbances of this rhythm are associated with many diseases.
The time changeimpacts our internal biological clock and can induce harmful effects on our health (sleep disorders, vigilance disorders, work and road accidents, depression, myocardial infarction and cerebrovascular accidents)”, details Inserm in an article.
“The body’s adaptation to this jet lag that we impose on it will vary from one individual to another and can last from a few days for morning chronotypes (people who tend to be more efficient in the morning), to several months. for late chronotypes (people who tend to be more efficient in the evening).” Young children and the elderly are most at risk of experiencing these negative effects. “But this is also the case for teenagers, night workers, and all those suffering from a sleep disorder who will have more difficulty adapting to the new schedule.”
The transition to summer time is more difficult to manage for the body
According to several chronobiologists, including neurobiologist and researcher at Inserm Claude Gronfier, President of the French Society of Chronobiology, the transition to summer time would be more difficult to manage for the organism because of the loss of a hour of sleep and the fact that the biological clock will also have to be advanced by one hour.
In 2019, the abolition of the seasonal time change was voted in France during an online consultation. A favorable vote was also made in the European Parliament and the end of the time change was scheduled for 2021, but member countries are struggling to tune their hands.
Winter time would be healthier
The majority of the French lean for their part to keep summer time. Nevertheless, the scientific community recommends opting for winter time. Indeed, with summer time, waking up in winter and falling asleep in summer would be physiologically more difficult.
On the shortest day of the year, December 21, the sun would rise in Paris at 9:41 a.m. (instead of 8:41 a.m. for winter time). Coming out of sleep in the morning, the body would therefore not have its dose of light to synchronize its biological clock. However, the scientific team of the Lyon Neuroscience Research Center observed that “certain exposures to light at very precise times have beneficial effects on the physiology of sleep and the non-visual functions of the body such as the secretion of melatonin (a hormone controlled by the circadian clock and involved in the regulation of sleep), pupillary reflex, brain activity, temperature and cardiovascular system“, And this, “even at very short exposures and very low light levels”.