If the ego or personal self isn't present to experience unconsciousness, how could any particular sleeper do so or form a memory of it? It's like a report of what life is like in the afterlife. There's no way the brain could process that information because the brain would have to be dead at that point.

My experience back then was a bizarre screwup of some kind. I was aware of the physiological aspects of unconsciousness from the outside, as it were. It was like the movie Inception except I didn't observe dream contents. But the fact that a shrunken version of my conscious self was intact throughout the ordeal is the only reason I can be said to have observed and remembered it.

I'm not at all interested in retriggering that accidental interference with my sleep cycle. But as I say at the end of the article, what's interesting is that the experience has some implications for the nature of consciousness, although they're hard to explain.