Comment by seadan83
Re: yawning
I listened to a "Science Vs" podcast on it (or perhaps it was "unexplainable"), yawning is not yo increase oxygen levels. Study participants sat in an oxygen enriched room and also a depleted room without a change in yawn rates.
What did affect yawn rates was brain temperature. Yawning lowers brain temperature. Importantly, when ambient temperature is higher than body temperature, yawn rate dramatically goes down.
These resource [1] [2] goes into some of the details if you want to skip listening to the podcast
[1] https://www.google.com/amp/s/www.pbs.org/newshour/amp/scienc...