(CN) – New research highlights a potential consequence of human-caused climate that extends beyond direct damage to the environment: disrupted sleep.
In a study published Friday in the journal Science Advances, researchers present findings which suggest that global warming could cost people in the United States millions of nights of sleep a year.
Each 1.8-degrees Fahrenheit increase in nighttime temperature will translate to three nights of sleep lost per 100 U.S. residents a month, according to the study. That translates to 110 million more nights of insufficient sleep each year.
“Too little sleep can make a person more susceptible to disease and chronic illness, and it can harm psychological well-being and cognitive functioning,” lead author Nick Obradovich said. “What our study shows is not only that ambient temperature can play a role in disrupting sleep but also that climate change might make the situation worse by driving up rates of sleep loss.”
Obradovich was inspired to examine the connection between warming temperatures and sleep during a heat wave that hit San Diego in October 2015. He was a doctoral student in political science at the University of California, San Diego, at the time and noticed that his fellow students also looked exhausted.
The study relies on data from 765,000 U.S. residents between 2002 and 2011 who responded to a public survey from the Centers for Disease Control and Prevention. The team linked the survey responses to daily temperature data from the National Centers for Environmental Information. Finally, the researchers combined the effects of warmer temperatures on sleep with climate-model projections.
The negative impact of warmer nights is most acute in summer – nearly three times as high as during any other season, according to the study. The research also predicts that people with incomes below $50,000 and individuals who are 65 or older will be the most affected. It will be three times worse for the lower-income group than for people who are better off financially if greenhouse gas emissions are not curbed.
Their findings represent the largest real-world study to establish a relationship between insufficient sleep and warmer nighttime temperatures, but it also has limitations. The CDC data relies on the responders’ memories, for example.
However, the study presents a new, concerning side effect of climate change – one that’s even more significant for people in hotter and poorer nations.
“The U.S. is relatively temperate and, in global terms, quite prosperous,” Obradovich said. “We don’t have sleep data from around the world, but assuming the pattern is similar, one can imagine that in places that are warmer or poorer or both, what we’d find could be even worse.”