We are close to release the Reality Expansion Pack V2.3 and with it you will get a newer hypoxia effect.
It will be much more real than the default X-Plane’s one.
Everytime you go up to the flight levels, the air is so thin that the amount of oxygen in it is too low to let you to breathe normally.
In the Cessna 210, to avoid this problem you can turn on the oxygen system. In the Bonanza, by the way, you do not have any oxygen system so all you can do is to descend to a lower altitude.
The effects of hypoxia are tunnel vision and difficult breathing, as you can see in this video:
Pretty scary, eh? 🙂