Why do we yawn?

Originally Published: March 2, 2001 - Last Updated / Reviewed On: January 11, 2013
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(1) Hello Alice,

I have a bet with someone on the correct meaning of a YAWN. I think it is because we yawn as our bodies aren't getting enough oxygen. He claims it is specifically from being tired? What is the correct meaning please and thanks?

(2)
Alice,

What is the purpose of a yawn?

Dear Readers,

Yawns are involuntary reactions to a variety of stimuli including being tired and seeing someone else yawn. But it doesn’t just happen after a long day or when you’re so bored you want to go to sleep. Yawning can happen even when you wake up after a good night’s rest. Despite the yawns reputation as something that happens when you’re feeling relatively inactive, it has been known to happen to paratroopers before their first parachute jump — hardly a dull experience! Experts and laypeople alike consider yawning to be “contagious” because when one person yawns someone else in the room is likely to follow suit. In fact, cutting edge yawn research has shown that yawning can be induced by talking about yawning, seeing a video of someone yawning or a still image of a person in mid yawn. Even reading about yawning can cause you to start yawning (you may have noticed this happening to you as you read this answer).

Yawning is more than simply opening your mouth wide and breathing in deeply, it’s a complex action involving stretching your facial muscles, narrowing or closing your eyes, tearing, and salivating. The physiological effects of yawning are equally varied. Yawning opens the Eustachian tubes connecting your ears to your oral cavity, as well as briefly (less than 20 seconds) increasing your alertness, among other things. Researchers have a hard time pinning down the exact meaning or purpose of yawning due to its multifaceted nature. Some people believe that yawning’s primary purpose is about oxygenating the blood. However, research has shown that yawning does not occur more frequently when blood oxygen levels become low. Experts seem to think that the true meaning of yawning may have to do with it’s social role which may be related to empathy; yawns seem to be connected to minor displeasure like feeling sleepy, mildly stressed, or bored — all of which may happen to you or your classmates during a 9 AM lecture.

So who wins the bet? It’s hard to say: yawning doesn’t happen only when you’re sleepy, but it’s also not about getting enough oxygen either. You may want to call this bet a draw.

Alice

January 17, 2013

521839
Well I think this is one of those questions that doesn't really have a concrete answer; it's kinda like ask why do we dream? Maybe there isn't a "reason" for that, or maybe it's impossible to know. I...
Well I think this is one of those questions that doesn't really have a concrete answer; it's kinda like ask why do we dream? Maybe there isn't a "reason" for that, or maybe it's impossible to know. I mean just look at mother nature itself, some other animals dream and yawn too, just like us. But why and what for, still remains unanswered. My personal opinion though is that yawning, just like stretching, is a practical way the body finds to increase blood levels on certain areas (face muscles and brain in this case), consequently producing an increase in alertness.