An astonishing new study claims that people are losing sleep for a very strange reason, and it has nothing to do with diet or stress. If you’re tossing and turning at night, it may be because of climate change, as global warming may be causing a rise in our core body temperatures the study found.

Researchers at Harvard University focuses on how rising temperatures could affect sleep patterns, analyzing responses of 765,000 Americans who were surveyed by the Centers for Disease Control and Prevention between 2002 and 2011, and they found that there was indeed a close correlation between bad sleep patterns and warm weather.

The researchers used information from regional weather reports when the survey stook place to examine the issue, and they found that respondents who said they didn’t sleep well had to deal with the most warm weather, especially hot summers. To break it down into numbers, for every month with an average of 1 degree Celsius higher than normal, three out of every 100 people lost a night of sleep.

“Climate change may keep you awake — and not just metaphorically,” a statement from the University of California San Diego reads. “Nights that are warmer than normal can harm human sleep, researchers show in a new paper, with the poor and elderly most affected. According to their findings, if climate change is not addressed, temperatures in 2050 could cost people in the United States millions of additional nights of insufficient sleep per year. By 2099, the figure could rise by several hundred million more nights of lost sleep annually.

“The study was led by Nick Obradovich, who conducted much of the research as a doctoral student in political science at the University of California San Diego. He was inspired to investigate the question by the heat wave that hit San Diego in October of 2015. Obradovich was having trouble sleeping. He tossed and he turned, the window AC in his North Park home providing little relief from the record-breaking temperatures. At school, he noticed that fellow students were also looking grumpy and bedraggled, and it got him thinking: Had anyone looked at what climate change might do to sleep?”