When outdoor nighttime temperatures topped 86°F, people lost an average of about 15 minutes a night. That may not sound like a lot, but it’s “actually quite a big deal,” says Sara Mednick, [professor of cognitive sciences], a sleep researcher at the University of California, Irvine. First off, other scientific studies suggest that those 15 minutes likely come from the uber-valuable “slow wave” sleep stage, she theorizes. We only get about an hour of that type of sleep a night, so taking away 15 minutes—or even five—cuts a big chunk of restorative time.

For the full story, please visit https://www.nationalgeographic.com/environment/article/climate-change-is-eroding-a-precious-resource-sleep.