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Health, Stuff, The Mind

Does hot weather make you act like an idiot?

. by ЯAFIK ♋ BERLIN, on FlickrAt the height of summer, tempers fray: drivers honk their horns and couples bicker in the car park. It’s a hot day and I’m in a rage because the person in front of me has decided to walk at a pace that would embarrass a very slow snail. With a mobility impairment.

‘GET OUT OF MY WAY! Can’t you see I’m in a rush?’

Mercifully, I refrain from shouting at the slow walking woman (with child) in the middle of the street. Thank goodness for good ol’ British self-control.

Along with men’s eye-wateringly white legs (revealed for the first time this year), odd things happen when the mercury rises up the scale. But can you really blame the weather for being an irrational grump? Or do you just need a vacation?

Does getting hot make you angry and irrational?

Body temperature doesn’t change very much. Sure, it goes up and down by a degree or so throughout the day, but on the most part it’s tightly controlled by our biological thermostat. However, force the body temperature up or down by more than a couple of degrees and you see some interesting changes.

If you were to put someone in a tank of hot water (41°C) and wait for their internal temperature to go up to about 39°C (similar to having a fever) then their brain stops functioning normally.

Back in 1985, this experiment was performed: a group of delightfully warm and soggy volunteers were given a variety of tests while floating in the heated bath (and slowly turning into a prune). They had faster than normal reaction times. And they also became more irritable.

You could say that they got irrational and snappy.

But it doesn’t just stop there…

Hot weather makes us sadistic

In more recent tests, volunteers playing video games in warm rooms get angrier and more hostile than in cool rooms. On a warm day we also become more suspicious of other people. But more worryingly, if we were to inflict a painful punishment on someone else then we would most probably be crueller if we were doing it in a hot environment.

It isn’t just in the lab: violent crime and murder rates increase in hot weather. It is also possible to predict the number of car-horn honks in a city from the temperature.

But why?

Similar changes happen in uncomfortably cold weather (only less so). It’s not clear what happens in the brain at extremes of temperatures, although it is most probably related to our inbuilt survival mechanisms: Staying in a very hot or cold environment for a prolonged period of time would be hazardous to health. Therefore, becoming fired-up makes us more likely to do something to move us into a more pleasant place.

Even if that means having a bust up with a family member and getting sent inside to simmer down.

My safety advice: Don’t go driving on a hot day. Avoid the crime ghettos when the sun is out. Sit in the shade with an ice cold glass of the drink of your choice. And relax.

It’s far better than shouting at a stranger in the street.

Thanks for reading – all opinions expressed are my own. Feel free to add your thoughts in the comments below.

References for the interested:

Craig A. Anderson, Kathryn B. Anderson, Nancy Dorr, Kristina M. DeNeve, & Mindy Flanagan (2000). Temperature and aggression Advances in Experimental Social Psychology, 32, 63-133

Rotton J, & Cohn EG (2000). Violence is a curvilinear function of temperature in Dallas: a replication. Journal of personality and social psychology, 78 (6), 1074-81 PMID: 10870909

Holland RL, Sayers JA, Keatinge WR, Davis HM, & Peswani R (1985). Effects of raised body temperature on reasoning, memory, and mood. Journal of applied physiology (Bethesda, Md. : 1985), 59 (6), 1823-7 PMID: 4077790

About Stuart Farrimond

I love writing about science and health subjects. Strange, because I also teach the same things. I trained as a medical doctor before turning my hand to other things. Shortlisted for The Guardian/Observer for Science Writer of the Year 2011 and editor for Guru Magazine I also like to grow large pumpkins...


5 thoughts on “Does hot weather make you act like an idiot?

  1. I find it interesting when the data bear out a commonly held belief. I half-expected, when clicking on the link to this post, to find that the data showed this piece of “common sense” was wrong.

    Posted by Jeremiah Stanghini | July 16, 2013, 12:24 am
  2. Dear Dr. Stu…..I would like to hear your hypothesis on why hot weather/climate increases sex drive and sex acts when clearly being too hot & sweaty makes one irritable and drained. Please your thoughts…..

    Posted by Debs | July 18, 2013, 8:14 am

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