Many studies on the impacts of climate change focus on extreme events such as hurricanes or floods.
But global warming is already affecting a daily and vital action for health: sleep.
A new study published in the journal One Earth by researchers in Denmark and Germany indicates that rising temperatures are negatively affecting night rest globally.
“Our study presents the first evidence on a planetary scale that warmer-than-average temperatures are eroding human sleep,” said Kelton Minor, a researcher at the University of Copenhagen and lead author of the study.
“We show that this erosion occurs mainly when the time people go to sleep is delayed and the time they wake up during hot weather is advanced.”
How much sleep are you missing
Researchers used data from sleep monitoring wristbands from 47,000 adults between 2015 Y 2017 in 68 countries.
Researchers say that by the end of the century suboptimal temperatures could cause us to lose, on average, between 50 a 58 hours of sleep per year.
But Minor emphasizes that the impact of climate change on rest is already a reality.
Lack of sleep affects the health and cognitive abilities. (Photo: GETTY IMAGES)
People are already losing an average of 44 hours of sleep each year.
Scientists also found that people sleep more when the outside temperature is below the °C.
Above this threshold, the probability of sleeping less than 7 hours increases.
And when the outside temperature exceeds 10 °C, people lose on average about 15 minutes per night.
Although it may seem like a minor loss, this decrease could take place in the stage of deep and restorative sleep called slow-wave sleep, whose first The phase lasts about an hour.
Which groups are most affected
The impact of temperature in sleep increases with age.
People older than 70 years lose about 30 minutes instead of 15 with a similar temperature.
Women are also more affected.
The study indicates that “under identical conditions , the core body temperature of women decreases earlier in the night compared to men, possibly exposing women to higher environmental temperatures around their usual time of onset of sleep”.
“It has also been shown that women have a greater thickness of subcutaneous fat, which could affect nocturnal heat loss.”
On the other hand, inhabitants of low- and middle-income countries experience an impact on sleep about three times greater than those of high-income countries.
It is possible that the higher prevalence of air conditioning in developed countries plays a key role, but the researchers clarified that they could not quantify its importance because they did not have data on access to air conditioning among study participants.
The impact of temperature on sleep increases with age. (Photo: GETTY IMAGES)
Lack of sleep not only affects our health but also our cognitive performance, according to previous research.
A study by José Guillermo Cedeño Laurent and his colleagues at Harvard University measured the impact of a heat wave of 2016 in students.
Students who slept in newer, air-conditioned dorms performed better on cognitive tests in subsequent days than those who lived in newer buildings. older and less adapted to increased temperature.
Body temperature
It has been known for a long time that hot days increase deaths and hospitalizations, but the biological mechanisms underlying these impacts are still poorly understood.
“Our bodies are highly adapted to maintain a stable core body temperature, something our lives depend on,” says Minor.
“However, every night they do something remarkable without that most of us are consciously aware of: they release heat from our core to the environment by dilating our blood vessels and increasing blood flow to our hands and feet.”
Minor adds that for our bodies transfer heat, the surrounding environment must be colder than us.
Researchers found that people have not changed their daily behavior to cope with the lack of sleep, such as taking a nap.
Scientists found no evidence that it is easier to sleep on a warm night in late summer than on a warm night in early summer. “We found no evidence that people are adapting well,” Minor said.
“The full spectrum of climate effects”
The global temperature at the level of the earth’s surface was on average 1,10 °C highest between 2011 Y 2020 to enter 1850 Y 1900, according to the August report 2021 of the UN Panel on Climate Change, IPCC.
A report by the Climate Action Tracker analysis center indicates that, without drastic cuts and taking into account current policies, the world is on the way to an increase in temperature by the end of the century of 2.7 °C compared to pre-industrial levels.
People in low- and middle-income countries experience a 3 times greater impact on sleep than those in high-income countries. (Photo: GETTY IMAGES)
The authors of the new study believe that due to the uneven impact on sleep in different populations, future research should especially consider the most vulnerable populations, particularly those residing in the hottest and poorest regions of the world.
Minor points out that the impact of temperature on sleep should be included in more studies on the possible consequences of global warming.
“In order to make informed decisions about climate policies in the future, we must take into account the full spectrum of plausible future climate impacts”, stated the researcher.
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