wrote:

When flying at night. I didn't believe it would make a difference
either until I tried (the most noticeable effect is the improvement
in your vision)

It is my understanding that it is time and age dependant.

Two questions; how old are you and do you see an immediate improvement
or does it depend on how long you are flying.

early 40s, but I heard similar comments from kids in their 30s. :-) The
improvement is noticeable quite rapidly (I'd say within minutes of
getting supplemental oxygen); for instance, the lights on the ground
that looked like seen through a little haze become sharp.

Get yourself through one of these high altitude training thing; you'll
be able to experiment a few other interesting side effects of hypoxia.

--Sylvain