Researchers from Lehigh and Northwestern Universities say, being in the heat makes people crankier, less cooperative, and less likely to help others.

In one experiment, researchers looked at the behavior of sales people in stores during a summer heatwave. And the data showed that on really hot days, in stores with no air conditioning, sales staff were 59% less likely to ask customers if they needed help, make suggestions, volunteer assistance, or even listen to the customers!

In another experiment, students attended a class in either an air-conditioned room, or one with no AC, on a stiflingly-hot summer day. After the class, students were asked to stay and complete an optional 100-question survey to help underprivileged children. Well, the students in the room with AC answered most of the survey questions. Students in the room with no AC? They only answered 6 questions out of 100 before bailing.

The researchers say, people are less helpful when the weather is uncomfortably hot. And these findings carry over into the workplace. And if companies want the best from their employees, they should keep them cool and comfortable.