[mlsu]

In general, anecdotes about "they raise the oxygen levels in [x] to induce [y]" are completely false. I've heard this about airplanes and casinos.

For one, it's really difficult/energy intensive to increase the level of oxygen in a space. Second, it's very very difficult to purify oxygen -- because oxygen oxidizes stuff. Even if you could do that, raising the level of oxygen is extremely dangerous, because it radically increases flammability of things and makes fire much worse. For an example of this: Apollo 1.