if yawning is caused by the brain’s need for oxygen, how does that relate to being tired?
In: Biology
Yawning can be caused by the brain needing oxygen but that is not the only possible cause of yawning. A lack of oxygen does cause you to become tired which is one of the things that can trigger yawning. The yawning might increase the oxygen in our blood which will releave some of the tiredness caused by lack of oxygen but will also cause you to wake up a bit, if only temporarily. This is however just a possible explanation for why we yawn when tired and it is not actually improving the oxygen levels in your blood by a lot so it may not be a good reason. However yawning is a very common social signal not only among people but also other social animals. It is also contaious so you may start to yawn when you see others do it. So it might have started as some way of releaving the lack of oxygen or making you wake up but it have evolved into more of a social message.
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