It's a very interesting phenomenon.

I think a lot of people dismiss phenomena like this, and say, "it's just such and such process in the brain", but I don't think that kind of explanation will ever get to the heart of the issue. To me, it's as if I ask "Why is JFK on the TV?" and someone says "The TV station is broadcasting signals which are being picked up by the antenna." It is an explanation, but it's quite obviously not the full story.

I like that you took the approach of saying, whatever they are, they do have an impact on people's lives. That's a very important point that many overlook. There's a hypothesis about John the Baptist, that he was a drowner - he induced NDEs in his followers, so they could experience this intense experience and "meet God", though nowadays of course, the baptism is conducted purely ceremonially, perhaps as a symbol of this practice. Personally, I think I'd rather go with the ketamine.