Posted at 5:00 a.m.
11 nights
According to a recent study published in the journal One Earth, the average Earthling already loses 44 hours of sleep each year due to above-average nighttime temperatures. That’s the equivalent of 11 nights with less than 7 hours of sleep, the generally accepted minimum. However, lack of sleep can have significant health consequences when it becomes chronic.
7 million
The study titled Rising temperatures erode human sleep globally analyzed data from 7 million nights in 47,000 people in 68 countries, from 2015 to 2017. Participants wore a bracelet on their wrist, connected to a mobile phone, which collected a lot of physiological data. Weather data was also taken into account. The research, conducted primarily by researchers at the University of Copenhagen, Denmark, was published last April.
Quantify the phenomenon
We already knew that too hot nights can affect sleep. The interest of this new study, according to DD Claudel Pétrin-Desrosiers, president of the Quebec Association of Physicians for the Environment, is that she quantifies the phenomenon. A situation that is not likely to improve by the end of the century. “Climate change is the greatest threat to human health in the 21ste century,” she recalls.
10 degrees
“Clear” effects on sleep were observed in all countries as soon as the night temperature was above 10 degrees. If the minimum temperature at night exceeds 25 degrees, the risks of not sleeping at least 7 hours are even higher.
15 nights
In a scenario of high greenhouse gas (GHG) emissions, rising temperatures could increase the number of nights of less than 7 hours to 15, on average, by the end of the century.
22 nights
People living in the hottest regions of the globe could experience up to 22 nights of less than 7 hours, by 2099. For those living in less affluent countries, which have less easy access to air conditioning, for example , this number of amputated nights of sleep could be up to three times higher, underlines the study. The authors admit, however, that they lack data on people from the world’s poorest countries. “People on low incomes are underrepresented in the data and we’re very transparent about that,” study leader Kelton Minor told the Daily. The Guardian.
The limits of the body
The study shows that heat-related sleep problems are greater in the hottest regions, thus suggesting limits to the adaptive capacities of the human body, beyond a certain threshold. “There are indeed limits for the body to adapt to such heat, explains the DD Petrin-Desrosiers. And several consecutive nights of poor sleep can have significant impacts. »
The women
Research points out that women are generally more affected than men by heat. Their bodies cool down earlier in the evening, so they are more affected by higher nighttime temperatures. They also have higher levels of subcutaneous fat on average, which can slow down the body’s cooling process.
Old people
The study also found that nighttime heat affects people aged 65 and over twice as much as an adult in their 40s. This effect is even more marked among those aged 70 and over.
Multiple consequences
While a poor night’s sleep can make us groggy the next day, lack of sleep can have adverse health effects if it becomes more frequent. The authors of the study recall in particular the consequences on cognitive performance and its effects on the immune and cardiovascular systems. Lack of sleep also affects mental health.
40.9 nights
According to forecasts by the Ouranos consortium, which specializes in the study of climate change in Quebec, Montreal could experience up to 40.9 nights when the temperature will be above 22 degrees by the end of the century. “Several consecutive days when it will be 26-27 degrees in an apartment without air conditioning in Montreal, it will become more and more frequent, reports the DD Petrin-Desrosiers. The impact of global warming will be disproportionate for the poor. »