Studies have shown that being in a warm environment decreases cognitive performance, while a short walk improves cognition. But what happens when you go for a short walk on a hot summer day, as so many students and office workers do during lunch or a midday break? It turns out you might be better off avoiding the heat.
Researchers at the University of Tsukuba found that just 15 minutes of walking outdoors on a hot day reduced cognitive performance, most notably in men who don't get enough sleep.
Those who work or study in urban heat islands, such as major cities in Japan, generally enjoy the convenience of indoor air conditioning during the summer months, which largely counteracts the negative impact of heat on learning and productivity. However, brief exposure to warm environments during commutes or breaks is unavoidable, and whether such exposure affects cognition is unknown. “Previous experiments have used specialized climate chambers to test these effects. However, the outdoor thermal environment differs significantly from the indoor thermal environments in terms of radiation and wind,” said senior author Professor Hiroyuki Kusaka. “Radiation and wind have significant effects on thermal perception. Therefore, experiments should be conducted in real outdoor environments to assess the effects of outdoor heat stress on cognitive performance.”
Researchers simulated a real-life scenario during the Japanese summer in which workers or students leave an air-conditioned indoor environment to walk or take a break in a warm urban outdoor environment. Ninety-six students completed a simple math test in an air-conditioned room before either staying indoors, walking outside, or resting outside for 15 minutes. Then they returned inside to complete a second math test, and any performance changes were measured. Walking in a hot outdoor environment reduced cognitive performance; however, it wasn't just exposure to the warm environment that diminished cognition. Rather, it was the combination of walking and being outside in the summer heat that affected cognitive performance. In addition, this effect was more pronounced in people, especially men, who were sleep deprived and had slept less than 5 hours.
“Japanese office workers and students, especially men, should be aware of this situation during their work and studies,” says Kusaka. The team hopes their findings will help improve productivity and learning for workers and students in Japan, and perhaps even beyond as the impact of climate change comes to the fore.
