Why do you yawn when you're tired or bored?

Ok, so I know that when you yawn, it means you need more oxygen. So why do you need more oxygen when you're bored, or when you're tired?
Answer:
Good question Christen. When we become tired, blood circulation slows and pools in vienules (very small viens). We instinctively stretch our muscles to work and squeeze the vienules to push the pooled blood out to circulate again. (This function is all hard-wired in the brain.) There is a great amount of blood circulation in the face, because this is where most of our senses are. As funny as it sounds, yawning is a way of stretching the face.

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Because like when your active, your musles work hard. It works the same way when your bored or tired. its your body and musles relaxing. Or simply because your tired and need sleep.

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I guess because when you're bored or tired you usually aren't very active.

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i think it's probably that ur brain lacks oxygen when u r tired and u yawn so that u take in more oxygen.

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