why people yawn oxygenWhy do people yawn? lack of oxygen to the brain, or lack of moisture in the eyes?

We yawn when we are bored AND tired. And that is because when we are bored and/or tired our breathing pattern slows and we inadvertantly take in less oxygen. The yawn is the result forcing us to take in a much larger breath so not to deprive the body of oxygen. Next time your tired, notice how much slower you breathe. And listen to someone breathe while they're sleeping. They take long deep breaths. That;s why we don't yawn in our sleep! The moisture in the eyes is from the lack of oxygen as well. (It's the same principle of strangulation, only not as severe)
I think your all wrong, they did a study that shows yawning decrease when the body has enough oxygen nor does it increase when the body lack oxygen...

lack of oxygen to brain and also for proper distribution of blood in why people yawn oxygenbrain
Probably lack of oxygen.
You created a false dichotomy. I don't think it's either. You yawn when you are communicating a change in circumstances, even if there is no one there to communicate with. For instance, if you are going to head to the bedroom to get ready for bed. But it could also be if you're at a party and are getting ready to leave.
Its to do with the brain needing a boost of oxygen.

But someone also once told me it also has to do with mimicry. You see someone yawning and you start to do the same you copy what you see. Its also the same if you see someone scratching themselves or saying they are itchy you start clawing yourself to. Its so weird, isn't it.

People also yawn when they are bored and have no interest in someone/something. They aren't being stimulated and the oxygen levels start to fall resuwhy people yawn oxygenlting in yawning.
Lack of oxygen to the brain!
Its from your brain momentarily forgetting to send the signal to breathe rhythmically. When your breathing is irregular yawning is your bodies best way of evening it out. That's why we yawn when we are tired because our brains aren't functioning at the same level as when we are fully alert. And some people yawn when they're bored because they are paying so much attention to their breathing that it becomes irregular.

And the reason yawning is contagious is because we are conditioned to regulate our behaviour according to certain social cues. The more innate the action, the more powerful the connection of 'hey he's doing that, I need to do it too'
ther are lots of rumers to why and about all of them are true