Marion Gauthier, edited by Laura Laplaud 07:29, May 25, 2022

According to a Danish study published in the journal "One Earth", rising temperatures lead to a disruption of our sleep cycles.

The Danish team collected data provided by 47,000 people, living in 68 different countries, equipped with a connected bracelet, which they crossed with local weather data.

You may already know that screens affect your sleep...just like global warming.

A Danish study published Friday, May 20 in the journal

One Earth

reveals that our nights will get shorter as temperatures rise.

Scientists analyzed connected bracelets, worn by nearly 47,000 adults living in 68 different countries.

In total, 7 million nights were recorded between 2015 and 2017.

Lack of sleep can have health consequences

To sleep well, you have to cool down.

When the body temperature is low, the body secretes more sleep hormones.

The outside temperature can therefore interfere with this process by delaying falling asleep and causing waking up during the night, as explained by Rachel Debs, head of the sleep unit at the Toulouse University Hospital.

"Beyond 25 degrees outside temperature, there will be a significant impact on the amount of hours of sleep. It is a decrease that has been noted, we go from short nights, to less than 7 hours."

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Still, 7 hours of sleep is enough time for a restful night.

The study shows that the risk of not reaching this minimum sleep is multiplied by 3.5 from the 25 degrees reached.

The consequences can be numerous, explains Rachel Debs: "Sleep is a recovery phase for different organs. For the brain, so if you sleep less, you have modified concentration and memory abilities, mood changes as well. , and other impacts such as weight, metabolism, more infection, etc."


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The study highlights inequalities, especially for older people who regulate heat less effectively and lose more sleep, just like people in developing countries.

The fault, perhaps, with the absence of air conditioning, according to the scientists.