Yes the problem isn't a lack of O2...it is actually an excess of it. Often people say, 'I am not getting enough air'...when in fact, they are (reverse) 'suffocating' in it! The blowing off of CO2, increases the PH of the blood, and constricts blood vessels to the brain...preventing the transport of O2, thus causing the symptoms that we all know too well!
Keep singing and blowing those bubbles everyone.:) (or do the breathing exercises...but B.R. knows which is more fun!)
S.C.