Do you feel a bit of brain fog in these hotter months? It’s logical to think that your sleep pattern may be to blame, but the heat may have a bigger influence on brain health than you realize. A few summers ago, researchers in Boston studied young adults living in college dorm rooms during a heat wave. Some of the participants had central air conditioning (AC) and slept in a 71-degree Fahrenheit (F) environment. Other participants did not have AC and the room averaged 80 degrees F.
For nearly two weeks of the study, students took a few tests every morning administered via their cell phones. The students who had to sleep in the hotter environment performed measurably worse on the tests than the students who slept in the cooler environment. One of the tests involved math, requiring simple addition and subtraction. A second test, the Stroop test, jumbled words and colors. If the participants saw the word “red” in a blue circle, they had to respond “blue,” according to the study authors.
If your reaction time is slower, then you may get tripped up more easily on certain questions. Researchers behind the study found that heat slows your reaction time. In fact, they saw reductions in the order of 10% in response times and accuracy. Part of that may stem from interrupted sleep, or lack of sleep. When the sleeping environment is hotter and you are not accustomed to heat, it is much more difficult to get quality sleep. That said, a body of research suggests that the heat itself interferes with cognition.
What Does Other Research Say?
A similar study from 2021 documented reduced cognitive performance at temperatures of 79 degrees F. As the temperatures rose during the study, researchers observed lower activity in the parasympathetic nervous system, which is the anti-stress system that can help you remain calm. Additionally, researchers noticed that oxygen saturation levels in the blood were much lower at higher temperatures. That most likely explained the reduction in cognitive performance.
Other studies found that higher temperatures in an office setting made office workers score lower on standardized tests. One of those studies found that productivity in the workplace was higher when the air temperature averaged 72 degrees F. Productivity began to decrease once temperatures reached the mid-70s. Additional research found that high school students performed more poorly on standardized tests when the days were hotter. Hotter days also made students more irritable or moodier, which may result from elevated cortisol levels. Too much cortisol in the body can induce frequent stress responses.
Given that extreme heat waves are more common nowadays, health experts are more interested in understanding how heat can influence mechanisms that influence anxiety-related problems and mood. A study from 2022 found that hospital visits for mental health-related issues rose during extremely hot weather. That is consistent with what a lot of physicians explain.
How Do You Combat The Effects Of Heat?
First and foremost, you need to hydrate as much as possible when the weather is hot. In hotter weather, you lose more sweat, so you have to replenish those fluids. In addition to water, drink electrolyte beverages (preferably not sugary sports drinks) that help replenish lost nutrients. In regards to the first study we discussed at the beginning of the article, students that slept in hot rooms drank less than six glasses of liquid per day. Prior research showed that being slightly dehydrated led to impaired cognitive performance. Drink plenty of water to keep your physical and mental health working optimally!
