I think nothing happens, you just die and the passing over operating tables and seeing yourself while your dead is either, a deep dream (we all have those anyway when they seem so real), made up to make us feel better or safe (others around us) or their high at the time.
The body and mind are more complex than we can understand at this moment in time, and I think this light or whatever is kind of a defence mechanism to numb the fear of death, for example I once seen a documentary about a man who fell into a huge cement mixer (Type of thing) and it was turned on, he said something like, it was tearing his limbs apart, he was bleeding to death, yet he felt so nice and like he was candy-floss floating around, but when the machine was stopped by someone, he was in so much pain it was unbearable.
Same here, had a dream I got shot in the back of the head, I woke up and could feel the blood and coldness there where I was shot, it was mad because it was like that for 5 minutes or more, by that time I was fully awake.
Point is our mind can trick itself into feeling things that are not there or are there but should have the adverse effect (pain being comfort), same as we try to trick ourselves and loved ones into the religious heaven and hell stuff, it's to make us and the people around us feel safe.
I don't believe in god one bit, but I tell my kids he exists, hypocrite maybe, but if it makes them feel safer to think they are going to live on even when they die, then I'm happy to be a hypocrite all day long.