[mrkgnao]

> you become dizzy with too much O2 in your blood

I've never heard of this, can you elaborate?

[ridgeguy]

This may be hyperventilation [1], which is too little CO2 in the blood, not too much O2. Symptoms include dizziness and loss of consciousness.

I discovered this in 7th grade by doing about 30 seconds of rapid breathing followed by holding my breath. Reliably passed out in 5-10 seconds, regained consciousness in <15 seconds.

[1] https://en.wikipedia.org/wiki/Hyperventilation