• Question: why do we yawn

    Asked by haleema <3 to Susan, Rebecca, Josh, Chris, Rob on 16 Jun 2015. This question was also asked by Zealousy, Jodi Proctor, krazykatie.
    • Photo: Rebecca Dewey

      Rebecca Dewey answered on 16 Jun 2015:

      There are lots of theories. They mostly agree that yawning is used by the body to keep us awake, or make us more alert. It could be to cool the brain, or to get more oxygen to the brain or to the limbs and other organs, but I don’t think scientists are completely decided on that!

    • Photo: Susan Cartwright

      Susan Cartwright answered on 16 Jun 2015:

      As Rebecca said, there are lots of theories: helping regulate temperature, stretching the jaw muscles, expelling excess carbon dioxide, increasing alertness. Some of these have evidence to support them: if you put an ice pack on someone’s head, they are less likely to yawn in response to a video of people yawning (supporting the idea that yawning may act to cool the brain). Some don’t – changing the oxygen or carbon dioxide content of the air wasn’t found to change the rate of yawning, which tends to suggest that taking in more oxygen or expelling carbon dioxide isn’t the main factor.

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