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What Makes You Yawn?

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Yawning, self-portrait
Joseph Ducreux

Today I want to talk about something that is infectious. This doesnít involve bugs. However, you might catch it just listening to me! I am talking about yawning.

Although the yawn may be triggered by physiological needs we donít yet understand, its origin seems almost entirely psychological. We often yawn simply because we see someone else yawning. Just hearing me talk about it may tempt you to yawn!

Physiologically, yawning may have some connection with a need to accelerate the body by inducing a more rapid and thorough exchange of carbon dioxide for oxygen.

Yawning is often accompanied by stretching movements. Other physical effects of yawning include opening the tubes between the ears and the throat, adjusting the air pressure in the middle ear, and watering the eyes and mouth. This latter effect results from pressure put on the tear and salivary glands.

The desire to yawn and the frequency of yawning is increased markedly with either boredom or sleep deprivation.

Itís curious that we tend to yawn shortly before sleeping and immediately after waking. If a yawn were simply to increase alertness by giving us an extra shot of oxygen, it would be inappropriate just before sleeping. Perhaps its main function at this point is to encourage relaxation. But weíre not sure. All this needs more research.

So next time you see someone yawning, be careful! Remember, itís catching!



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