How Do You Explain "Near Death Experiences"?

I don't mean far out there claims that cannot be proven... (e.g. I floated on an Amber Bubble to Kingdom Hall and God said "You aren't done" and I went back into my body).

I'm talking about people who saw themselves on an operating table, and can describe tools the doctors used, conversations they had, how people were operating on their body. 

You know, stuff like that. How can it be explained?