I wouldn't even consider oxygen deprivation a means to improve brain activity without consulting a physician first.
I might guess that the reason you don't want to consult your doctor about this is because you already know there's a 90% chance your doctor is going to tell you this is "new age bullsh*t" ... and you know he or she will probably think less of you for even considering such a thing.
Without meaning to offend, I think your doctor would be right. There are a lot of new age profiteers and genuinely lost and confused souls who get sold on the idea that some activity that triggers a change in conciousness or perception is also going to produce some other useful and sometimes even magical result. Some are offered hope that Brainwave entrainment makes you smarter or better or even psychic because they experience a certain tiredness or dreaminess. Maybe it does make you psychic, but then again, maybe it just makes you tired and dreamy. Same thing with marijuana, although very few people confuse getting high with spiritual enlightenment today, it used to be the Holosync of its time -- with some potentially negative social and physical side effects. Holding your breath or denying oxygen to your brain and then taking a big gulp of oxygen will trigger a real response, probably unpleasant. Don't let anyone tell you that the diziness and nausea is proof that its working and that you'll get added benifits later. It's probably just proof you're killing brain cells and they probably don't grow back.
I should refer you to Wim Wenger's self-read audio rendition of The Einstein Factor. He sounds even more like he may have experienced some kind of brain damage with slurred speech as a result than in the Genius Code. I wouldn't want to sample the same medicine as that guy's been taking.
Bottom Line: There are hundreds if not thousands of ways to improve yourself physically and mentally. Why pick the one that risks brain damage? Why not try some other practice first?
Best,
-- B.
