Summer heatwaves may slow down our brains, according to new research published in PLOS Medicine. For the study, which confirms what many groggily suspected, researchers asked 44 college students, only half of whom lived in air conditioned dorms, to take daily math tests on their smartphones when they woke up each morning, for two weeks. They found that students waking up to air temperatures near 80 degrees performed worse on these tests, and answered more slowly, than students living in air-conditioned dorms.
“Students who were in the non-air-conditioned buildings actually had slower reaction times,” coauthor on the study Joe Allen of Harvard University told NPR. “Thirteen percent lower performance on basic arithmetic tests, and nearly a 10 percent reduction in the number of correct responses per minute.”
This is not the first study to demonstrate that heat slows cognition. In 2006, researchers noted that employees perform poorly as office temperatures near 80 degrees and more recent work has confirmed that high office temperatures are among the major factors that can hinder productivity. High school students, too, have been shown to perform poorly on standardized tests when exams are administered on very hot days. Allen and colleagues’ new study, despite its small sample size, adds to a growing body of research on how heat clouds our minds.
In the office and in the classroom, this emphasizes the importance of keeping an air conditioner up and running. Employees and students simply do not perform well when they are sweltering. But the findings have perhaps more dire implications for people working in factories and riskier environments, where poor cognition can lead to workplace accidents or fatal mistakes.
These concerns drive home the importance of remaining hydrated and cool during the summer months. Basic precautionary steps such as these can help mitigate “heat exposures among populations normally considered resilient to them,” according to the study. “Especially in settings in which cognitive processes are critical to ensuring learning, safety, or productivity.”