Climate Change Could Erode Your Sleep

Add another tally to the "woes of climate change" column. A new study suggests that by the year 2099, people will get as many as 58 fewer hours of sleep annually due to the impacts of heat on slumber. Researchers had 47,000 adults in 68 countries wear sleep-tracking wristbands for six months on average between 2015 and 2017. CNN reports an analysis of the 7 million sleep records that resulted indicated that the likelihood of getting fewer than the recommended minimum 7 hours of sleep a night increased by 3.5% if the outside temp was above 77 degrees at night, as compared with temps in the 41- to 50-degree range. What that looks like in minutes: On very warm nights, defined as over 86 degrees, sleep time dropped by about 14 minutes.

"In this study, we provide the first planetary-scale evidence that warmer-than-average temperatures erode human sleep," says lead author Kelton Minor of the University of Copenhagen 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." And the sleep erosion didn't hit people equally. "The elderly, residents of lower-income countries, females, and those already living in hotter climates are disproportionately impacted," per the study published in One Earth.

The Guardian explains some of the science behind that last finding: Our bodies cool prior to the onset of sleep. In addition to having more subcutaneous fat, women's bodies "cool earlier in the evening than men’s when going to sleep, meaning higher night time temperatures may have a bigger impact on women." It adds that older people's body temperature regulation isn't as good, and people in lower-income countries may not have cooling devices, like fans and air-conditioners, at their disposal. Minor says the reality might end up being worse: "It’s very likely our estimates are conservative." (More climate change stories.)