Burnt out: heatwaves can lead to poor decisions and thinking, studies say

Arwa Mahdawi
A heatwave can fry the brain. Photograph: aryos/Getty Images

If you feel like having to work during a heatwave should be banned, you may have a point. A new study conducted by the Harvard TH Chan School of Public Health suggests that hot weather can make your thinking 13% slower.

The study, published on Tuesday in the journal PLOS Medicine, examined cognitive performance during a 2016 Boston heatwave among students who lived in buildings without air conditioning versus those who had it. Researchers found that students without air conditioning demonstrated about a 13% longer reaction time on cognitive tests compared with students who had AC. Not only were the students who had air conditioning faster in their responses, they were also more accurate.

The study suggests this decrease in cognitive ability might be attributable to “an increase in thermal load” along with the combined influence of other factors associated with heat exposure including sleep loss and dehydration.

In a statement, Jose Guillermo Cedeño-Laurent, a lead author of the study, said that “knowing what the risks [of excessive heat] are across different populations is critical considering that in many cities ... the number of heat waves is projected to increase due to climate change”. Examining the impact of indoor temperatures is also important, considering that adults in America spend 90% of their time indoors.

While this study was fairly limited in scope, looking at just 44 students, there has been some other research that shows hot weather can impair our decision-making or cause us to just give up on making decisions altogether. A 2012 study, for example, examined sales data for lottery games in St Louis county across a full year. The researchers found that sales of scratch tickets, which require a choice between various options, fell by $594 with every 1F increase in temperature. Meanwhile, sales for lotto tickets, on which buyers are faced with far fewer decisions, were not affected by temperature changes.

In the same study, researchers also asked participants to proofread an article in a room that was either warm (77F/25C) or cool (67F/19C). They found that those in warm rooms made significantly more errors than those in the cooler room. In a subsequent study, they asked participants to choose between different cellphone plans in a warm room or a cool room. People in the warmer room picked the worse plans, leading researchers to conclude that heat makes people likely to rely on less sophisticated patterns of decision-making, which leads to worse choices.

All of this is not say that you should start cranking up the air conditioning at work: that opens up a whole new set of problems, as women tend to feel colder than men do at the same air temperature. Studies have found that women prefer rooms at 77F (25C), and men prefer the temperature to be set to 72F (22C). Further, working in heavily air conditioned offices has been linked to lower productivity and in increase in icy behavior from women who are sick of AC standards being tailored around men.