Why do we yawn?

Answer 1

No one is sure. It has something to do with stretching and relaxing the muscles, in preparation for sleep. However, they also know that yawning can increase alertness. Research continues...

Here is the Wikipedia page with all the info on yawning:
http://en.wikipedia.org/wiki/Yawn

Answer 2

We yawn because when we experience a lack of oxygen in the body. The sole purpose of a yawn is to take in more air.

Answer 3

your answer as to why we yawn would be that sometimes our brains, yes believe it true, need more oxygen. This is apparent when we are pretty tired or when we, out of no where, just yawn. Its just a way of re-oxygenating our bodies as well as our brains. some people have a different breathing pattern and they dont get as much oxygen in their bodies because their breathing rate is a bit slower than what the breathing rate should be.

i hope that this answers your question thoroughly.

Answer 4

Could be between two reasons. We are tired so we yawn to get a rush of oxygen to our body to wake us up, or our brain is has a lack of oxygen at the moment and we yawn to get a rush of oxygen to it♥

Answer 5

When we are bored or sleepy so we yawn to raise out alertness.

Answer 6

we're not breathing properly/evenly and our body wants more oxygen in the blood, thus forcing you to yawn..

Answer 7

It is because there is a lack of oxygen to the brain.

Answer 8

Cause it's fun? Kidding-apparently like hiccups, it's telling us we need a sudden boost of o2 in our lungs

Answer 9

Cause we stayed up too late last night playing playstation

Answer 10

It is our body telling us that Dan Aykroyd movies are achieving their intended purpose.