I definitely think it has to do with the lack of oxygen. I almost drowned when I was about 15. Believe it or not, it was the fault of a 5 year old...anyway, something unnerving happened to me and then I had my OTHER freaky experience (still in the water).
The kid had latched onto me in such a way that I could not move my arms and she was facing my face. I was seriously losing the fight and had inhaled loads of water...the last thing I did before I...whatever happened to me...was start headbutting her and biting her face in an effort to get her to let go of me. I call this unnerving because I would never in my wildest dreams imagine that I would purposely seek to harm a child at all and I was biting her so hard that she had scars on her face from it. But a switch had been flipped and it seems my reptile brain took over.
Then I was simply not there anymore. Everything in reality ceased to be and I did the whole life-before-your-eyes thing and everything went white. Next thing I knew, I was coming to on the other side of the creek (mind you, now, it was an insanely deep and large creek, a true Arkansas creek if ever there was one). Her brother was there and he was tending to her wounds and giving me what I considered a pretty harsh look seeing as she almost killed me, and a friend of mine was rolling me out of my own vomit. Pretty, I know.
They said I was pretty fuckin' brutal, though, before going under for the last time. I barely remember attacking her, just feeling shocked because there was a part of me freaking out about what I was doing to her, but the part in charge was screaming "fuck her! let her die!"...
Anyway, I didn't get a hallway or anything, I just got my little movie and then the full white screen.