Global warming also influences the way we sleep. This is the first time that a study has been conducted on this subject on a global scale. These researchers analyzed the sleep of 47,000 people in 68 different countries, using sensors on bracelets and compared the results to local weather data. First lesson: the probability of sleeping less than seven hours a night is multiplied by three as soon as the temperature exceeds 25°C outside because the heat delays falling asleep. On average, global warming already causes each inhabitant of the planet to lose 44 hours of sleep per year on average. By the end of the century we could lose up to 58 hours if we keep the same trajectory, which is the equivalent of seven sleepless nights over the year, if we take an average of eight hours of sleep per night.
In fact, the human body doesn’t adapt that well to heat. The researchers themselves were surprised, sleep is more disturbed than they initially thought. Because it is physiological, our body needs to cool off during sleep, the body temperature should normally drop during the night until the early morning. For this, the body releases heat to the outside by dilating the blood vessels, but obviously for the heat exchange to take place, the surrounding temperature must be sufficiently cool.
All this means that behind the average, which is very global, certain populations are even more vulnerable: the loss of sleep is three times higher than the average: for the populations of the less wealthy countries, which have fans less often, air conditioning or even shutters, and it is twice as high as the average for those over 65, because it’s a fact, we regulate our body temperature less well as we age.
The researchers raise the alert. Since the quality of sleep is essential for preserving cardiovascular health, mental and cerebral balance and good immunity, this impact of global warming must be taken into account by political decision-makers, believe the researchers. In particular for the development of cities, the fight against heat islands, and the insulation of housing.