Why do we yawn?

Dont really have a reason asking, just curious.

It's a reflex in place to increase blood flow (and, thus, oxygenation) to the brain, IIRC.

Which means that it only happens wen we are tired and our blood flows rather slowly?

Mags said:

Which means that it only happens wen we are tired and our blood flows rather slowly?

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I don't think blood flows slower than a certain threshold (as when you're resting.
BRB
It is definitely a reflex and my first answer may not be a complete/definite one. Link

We yawn because a flashlight is to dim and yellow.

73
dim

Yawning is definitely a mystery. I see my turtles yawn when they are under water so I know it isn't to increase oxygen in the body. They are already holding their breath as it is.

Maybe they just think I'm boring... :sleepy:

It seems nobody knows:
http://science.howstuffworks.com/question572.htm

Isn't that a Chinese thing? Yin & Yawn?

dcarch8

I thought it was a reflex to protect your eyes from the sun.

Thats another things thats always confused me - lots of people sneeze when they look at the sun..

Piers

It's also a social thing that we have inherit from a long time ago. Yawning is a way of telling the group that it is time to move on to the next thing, sleep, eat, get up and do something etcetera.
If you are a group of people and someone yawns, you usually are about to end what you are currently doing.
I read it in "Illustrarad Vetenskap" (Illustrated Science, a Swedish science magazine) some time ago.

Pook said:

Thats another things thats always confused me - lots of people sneeze when they look at the sun..

Piers

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Thats me! It really bothers me, ever time I come out of class into the bright sun, I have to sneeze. Who else is like that?

If thats the case why am I around 6 dogs that yawn and many cats that yawn.

I think I recall something about a fairly quick change in barometric pressure
causes a yawn not the only one but a factor.
Topper

JonSidneyB said:

If thats the case why am I around 6 dogs that yawn and many cats that yawn.

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Little babies yawn too. It's hard to imagine that being a learned social trick.

Exposure to bright halogen lights always makes me yawn. I haven't figured out why.:shrug:

Its to keep us awake.

I read that somewhere.

A few years ago I had 17 snakes as pets. They yawned all the time! I cant imagine being any more bored than a snake in a cage!? My dog and 3 cats yawn. I read somewhere that it to increase oxygen intake, cannot remember where.

Yawnin's contagious...

Sometimes subconsciously i yawn when i see others yawn on the train, or anywhere for that matter.. But sometimes i do see someone yawn and tell myself: "No. You won't juz follow.. " Any one else has this syndrom (is that way to spell it? suddenly i juz forgot.) yawwwnnzz...

Pook said:

Thats another things thats always confused me - lots of people sneeze when they look at the sun..

Piers

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I heard that any bright light stimulates the little hairs in our nose, causing a tickling sensation and therefore we sneeze. Ever feel a sneeze coming, but it won't come out...look at a bright light........gazzontight !!!

Ever have to sneeze, but you just don't want to make that loud noise ? Just tickle the roof of your mouth with your tongue and it should make the sneeze go away for a while.

Yawning...that sudden deep inhale we do may be to introduce new foriegn substances (bacteria, germs, cooties) so that our body can learn to fight and eliminate them. This was one persons theory on some tv channel. So if you have to yawn because someone else just did, try not to suck in the air they expelled.