spektrum, I trust you are not questioning my ability, fitness or health. I followed my employers instructions regarding the use of O2 above 5000 at night as did my colleagues.
Perhaps as it appears as though you do not understand some aspects of the human body that you should avail yourself of a visit to a facility with a Hypobaric Chamber and undertake their course.
I believe you will not only be surprised by the experience but you may also be enlightened.
CC