Why We Yawn

Previous explanations claim that yawning provides a boost of oxygen, but there’s little evidence to support that. To test the hypothesis that it helps regulate brain temperature, researchers observed yawning patterns among people outdoors in Austria and Arizona and found that people are most likely to succumb to a bout of contagious yawning when the mercury is hovering around 68 degrees Farenheit. Meanwhile, yawning wanes below freezing and above 98.6 (normal body temperature). The study authors believe that’s because the mechanism uses ambient air to cool the brain, which it can’t do if it’s too hot or dangerously cold outside.

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