Hot weather: Why it's normal to feel grumpy in the heat

Think back to the last time you felt insanely hot. It may have been on the beach. It may have been at work. It could have been during the night recently. Few of us are able to sleep during hot weather, after all.

One thing's for sure: you probably felt a little irritable. And there’s a good reason for that.

Experts have theorised that factors such as a lack of sleep and dehydration due to the heat can lead to increased aggression and a general bad mood.

But various studies have proven the link between hot weather and bad moods exists.

Researchers at Pennsylvania's Lehigh University decided to test the theory that heat causes antisocial behaviour.

Professor Liuba Belkin led the three-part study which looked at three different environments.

Read more: Does drinking hot drinks really cool you down?

The first analysed secret shopper data from a Russian shop. They compared reports from July and August of 2011 – a normal summer – to the same months in 2010 when Moscow was experiencing a mega heatwave.

In the summer of 2010, secret shoppers' data showed a significant drop in the helpfulness from store employees.

Researchers found that 59% of retail employees were less likely to help customers as well as make suggestions and listen actively.

Belkin believed the heat was the reason for the change in attitude. "To our knowledge, this was the first study to establish the connection between ambient temperature and a reduction of prosocial behaviour with data," she told Quartz at the time.

However, other experiments have proven similar behaviours. One Minnesota-based study even showed that we're more likely to tip more generously on cooler days.

Read more: What happens to your body when it gets too hot?

Belkin went further, embarking on two more studies that examined the relationship between heat and how people felt.

She recruited 160 subjects in the US, asking half of them to close their eyes and think of a time when they felt extremely hot. Participants were then asked to answer survey questions about their mood and energy levels followed by a round of trivia questions.

Finally, they were asked to fill in an extra survey as a final courtesy.

A control group did the exact same thing. However, they weren't asked to recall a warm environment.

The results showed that 44% of the first group agreed to the optional survey compared to a much higher 77% in the control group. The first group also reported suffering from fatigue and lower moods more than the second did.

Belkin concluded that simply thinking about a hot environment can lead to tiredness and a bad mood.

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The final study involved a group of students. Some were made to listen to a lecture in a room with a temperature of 26.7 degrees. Another class did the same but in a fully air-conditioned room.

Both classes were asked to answer some questions and then fill out a 100 question survey.

The people in the hot room answered an average of six questions whereas the students in the cooler location answered an average of 35.

"The point of our study is that ambient temperature affects individual states that shape emotional and behavioural reactions," Belkin added. "So people help less in an uncomfortable environment, whatever the reason they come up with to justify why they cannot do something."

If your office is complaining about a less-than-productive workforce, try hinting at a better air con system, or make sure you crack some windows open at home and rummage around for that fan.

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