There was a time when I was so obsessed with Near Death Experiences (NDEs) that I wished I had one myself. That was, however, at the start of my spiritual journey. As I progressed in my spiritual journey, I had what people label as Spiritual Experiences (SEs) and now, I feel these are much more gentle. I have come to the personal conclusion that not all of us need NDEs to learn spiritual lessons, and that perhaps those who do needed something much more drastic to "wake up". There is no judgment in what I just wrote. It's just an observation.
I want to recommend three books if you want to learn about NDEs: the first book is called After by Dr Greyson, the second is Dying to be Me by Anita Moorjani and the third is Proof of Heaven by Eben Alexander.
Contrary to popular belief, not all NDEs are pleasant. Not everyone goes to "heaven". Some people go through to a very dark place that some even describe as Hell. My understanding of this is the reason you go to the place of light as opposed to the place of darkness has nothing to do with how good you have been but more to do with the proportion of light you have inside of you as opposed to the darkness. We all have both light and darkness in us. Anyone who tells you that they are pure light is lying to you. As humans, we are born into duality. And we all have done things when gripped with fear that we are not very proud of.
What are the main teachings that Near Death Experiencers bring back from their experience?