What causes us to yawn?

Question

Now, chances are you all going to tell me it's because of a lack of Oxygen. ITS NOT.

It may be in some cases, but not always, so it's not the simple solution I have seen so many times on this website.

I often yawn with barely any breath being taken in, it's more of a stretch than a yawn. Plus, fetuses (or whatever the plural is) have been observed yawning and they're in the womb, they don't breathe!

Plus, wouldn't there be a simpler way to intake more air other than yawning? Like a massive hiccup?

Answer 1

i thought the exact cause wasn't known.

but tiredness makes it more likely, and so does other people around you yawning. and dogs can catch a yawn from humans lol.

Answer 2

damm...  just looking at the word made me YAWN

Answer 3

I was told that one possible reason that yawns are contagious is the "animal" side of us showing off our teeth. It's a non-threatening way of showing you've got menacing teeth.

I'm not 100% sure about this, and it would only be one reason for yawning if it was true.

Answer 4

Yawning is an involuntary act usually associated with drowsiness or boredom, in which mouth is opened wide and slow, deep breath taken through it. Yawning is accompanied by a momentary increase in heart rate;slight constriction of sum blood capillaries, and in many cases, watering of the eyes (possibly because the pressure on the tear glands as a result of facial movements).

The purpose of yawning is unknown, but one theory suggests that it is triggered by raised levels of carbon dioxide in the blood; thus, its purpose may be to reduce blood carbon dioxide level and increase the blood oxygen level.

Answer 5

being tired..