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[Yawn] Oh, sorry. I'm not tired, my brain's just overheated.
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At least that's what a new study says. Researchers at the University of Vienna found that the
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amount of yawning we do increases when our brains are hot. (Via ScienceDirect)
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"Much like a computer, your brain works best at a certain temperature and tries to avoid
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over-heating. And it turns out, yawning increases your heart rate, blood flow and the use of
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muscles in your face, which are all essential to cooling the brain." (Via YouTube / AsapSCIENCE
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)
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So, why is yawning associated with being tired? Well, exhaustion and sleep deprivation are
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known to increase overall brain temperature. (Via Flickr / twob / nate2009)
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But as the Daily Mail points out, researchers found people yawn less when it's hotter than
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normal body temperature outside, which makes sense — you would be breathing in hot air.
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Not exactly cooling.
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The research says people also yawn less at the other extreme. When it's super cold outside
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— like, say, frozen — brain cooling may not be necessary. (Via Walt Disney Studios
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/ "Frozen")
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Time notes this study builds on research that showed yawns are preceded by sporadic rises
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in brain temperatures and are followed immediately by decreases in brain temps.
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We still don't know why yawning is contagious, but the researchers argue it might be an evolutionary
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trait to improve overall alertness.
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TED says it's an empathetic response.
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"In fact, contagious yawning starts occurring when we are about 4 or 5 years old, at the
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point when children develop the ability to identify other emotions properly."
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And now I'll be yawning all day.