Sunday October 27 at 3 am, France will switch to winter time. Unsurprisingly, this time change upsets our biological clock, with harmful consequences for the body. But what is really going on in our body at this time?
It’s the time of year we all dread. November is coming, winter is approaching and with it the dreaded time change. The transition to winter time will take place on Sunday October 27 at 3 am. It will then be necessary to remove 60 minutes from legal time. Introduced in France following the oil shocks of 1973-1974 to save energy, this time change disrupts the biological clock and can therefore have various unpleasant consequences on the body. According to some scientists, it would be even more harmful to health than jet lag related to changes of time zones during travel. Why Doctor takes stock.
1/ A hormonal upheaval and sleep disturbance
Unsurprisingly, the main disturbance concerns sleep. The latter, which operates in 24-hour cycles, can be disrupted for several days following a time change. If the transition to summer time, which cuts our nights by one hour, is more brutal, that to winter time can also cause inconvenience. Because, overall, the time change influences the biological clock and therefore the secretion of the sleep hormone: melatonin. “We fall asleep at night when the melatonin peak occurs. However, the transition to winter time will modify its secretion”, explains Dr Marie-Laurence Vent, pneumolologist and co-head of the unit dedicated to sleep at the Vichy hospital center, in LaMontagne.fr.
2/ A possible mood disturbance
This lack of sleep can lead to drowsiness, loss of concentration, nervousness and end up cruelly degrading the mood. The transition to winter time can also have a psychological influence on seasonal depression, associated with reduced exposure to daylight. In detail, this combines with the drop in melatonin production to block the happiness hormone, serotonin, causing mood swings and chronic irritability. This phenomenon would affect about one in six people, especially women.
3/ Blood pressure, heart rate, body temperature
If there are several clocks in our body, the main one is located in the brain, in the suprachiasmatic nucleus of the hypothalamus. The latter coordinates all our biological rhythms. Thus, “the time change disrupts our internal clock which controls our different biological rhythms. These rhythms correspond to the periodic variations of a physiological function. Blood pressure, heart rate, body temperature, sleep-wake cycles and even mood and attention vary throughout the day,” explains Véronique Fabre, research fellow at the Neurosciences Paris Seine-IBPS laboratory (Sorbonne University /CNRS/Inserm) on the Sorbonne website.
4/ A disturbance of the appetite
A disturbed rhythm can lead to loss of appetite. Our stomach has to get used to experiencing the feeling of hunger again at a different time. In some people, however, it happens on the contrary that the upheaval in the secretion of leptin and gherlin, hormones that regulate appetite, increase it.
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