Summer is unbearable. The fiery rays of the sun, those sweat-soaked shirts and the chafing between your legs all make it hard to be chipper on those 100-degree days. Thankfully, science is on your side with a new study that says hot weather can be blamed for your bad attitude.

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Quartz reports on research from Professors Liuba Belkin of Lehigh University in Bethlehem, Pennsylvania, and Maryam Kouchaki, assistant professor at Northwestern in Evanston, Illinois, who found that environmental temperatures actually reduce prosocial behavior.

Analyzing data from a retailer in Russia, the professors compared secret shopper feedback from summer 2011, which had temperatures representative of a typical summer in Moscow, to 2010 during the city’s heatwave. According to the article, in 2010, customer service associates were 59 percent less likely to offer customers help, ask if they were shopping for something in particular, listen or make suggestions. Quartz writes that the store itself remained in the same condition and that customer service training had not been added the following year.

“To our knowledge, this was the first study to establish the connection between ambient temperature and a reduction of prosocial behavior with data,” Belkin said in Quartz.

Wanting to find out why people weren’t helpful in the heat, the team enlisted 160 Americans to complete an online survey. First, 80 people had to remember a time they were very warm before answering questions about attitude and energy. Next they answered trivia questions and were asked to complete one last survey as a bonus. The other half completed everything as the first group except they didn’t visualize being warm. The researchers found that only 44 percent of the warm memory group agreed to the additional survey compared to 77 percent of the control.

Belkin told Quartz that simply thinking of the heat made people more tired and fatigued, which led to more antisocial, unfriendly attitudes.

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The researchers performed one last study in one of Belkin’s classes. Students sat through a lecture in a room reaching 80 degrees Fahrenheit in one class session while students in another section listened to the same lecture in an air conditioned space. At the end, they were asked to complete a 100-question survey which was being used to help underprivileged children. On average, students in the air conditioned room completed 35 questions, compared to six in the other.

“The point of our study is that ambient temperature affects individual states that shape emotional and behavioral reactions,” Belkin told Quartz.

Not only does the heat make us cranky, but apparently it causes people to commit more crimes too. A study from 2012 indicated that the heat is linked to aggression and violence. Researchers attribute these mood changes to sleepless nights, dehydration and being cooped up due to the weather.

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