Not getting enough sleep? Well, bad news: Climate change might just make things much, much worse.
In a new study published Friday in the journal One Earth, researchers in Denmark have found that as the planet warms due to climate change, how much sleep we get a night may tank because of how poorly our bodies respond to heat. This reduction in such an essential bodily function could have an even bigger negative impact on people vulnerable to heat, like older adults, or those living in low-income areas and countries.
“In this study, we provide the first planetary-scale evidence that warmer-than-average temperatures erode human sleep,” Kelton Minor, a doctoral student at the University of Copenhagen and the study’s lead author, said in a press release. “We show that this erosion occurs primarily by delaying when people fall asleep and by advancing when they wake up during hot weather.”
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The team analyzed 7 million anonymous sleep records collected from sleep-tracking wristbands from more than 47,000 adults across 68 countries. The study took a look at how many hours of sleep users got at night when they slept, their geographical location, and climate. The researchers found adults fall asleep later, rise earlier, and sleep less during hot nights when temperatures were 86 degrees Fahrenheit or higher.
There’s a physiological reason for this: When we sleep, we naturally release heat from our bodies to maintain our body’s core temperature. Past studies have shown we can adapt heat release in colder temperatures, but not so well for hotter temperatures. To sleep well, we need to be sleeping in a room or area that’s cooler than us.
People living in developing countries seemed to be hardest hit by the spike in the temperatures, as well as older adults and women, who are more sensitive to temperature than men. While this analysis is far from a complete picture of what happens to sleep in a world on fire, it's mounting evidence of climate change’s immediate and potentially devastating effect on our health.
“In order to make informed climate policy decisions moving forward,” said Minor, “we need to better account for the full spectrum of plausible future climate impacts extending from today's societal greenhouse gas emissions choices.”
