• Question: Why do we yawn?

    Asked by scientists321 to Anouk, Chris, Judith, Leisha, Seyyed on 19 Jun 2012. This question was also asked by erinmason30.
    • Photo: Judith Sleeman

      Judith Sleeman answered on 19 Jun 2012:

      My old home economics (domestic science?) teacher used to say it was lack of oxygen when we yawned in her lessons. So she used to open all the windows all the way, even in the middle of winter, to teach us a lesson! Not sure if it’s true, or if she was just being mean.

    • Photo: Chris Kettle

      Chris Kettle answered on 19 Jun 2012:

      It was always believed that it was due to la k of oxygen and that our bodies needed a sudden oxygen rush- hence the uncontrollable nature of a yawn. Itsblieved that a yawn is contagious as others in your group would realise that oxygen was low and take great gulps air

    • Photo: Anouk Gouvras

      Anouk Gouvras answered on 20 Jun 2012:

      No one knows for sure but yes the lack of oxygen seems the most plausible explanation. And people have suggested that when tired or bored you breath less deeply so the body yawns to take deep gulps of air and oxygen. However studies have not confirmed this as even when breathing more oxygen this does not decrease yawning. So we still don’t know if this is the correct explanation. Another theory is that yawning is a way of stretch the lungs and the lung tissue as well as muscles and joints, increase blood pressure and hence make you feel more awake. And yet another theory is that it helps re-distribute surfactant, a substance that lubricates the lungs.
      In Africa, whenever I yawned people asked me if I was hungry. The associated yawning with hunger.

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