M. Tesla, you have narrowed your topic to Near-Death Experiences when in fact the larger question might be about experiences beyond this physical existence, or experiencing ourselves in the afterlife while we still have a viable physical body here on earth, of which a near death-experience is only one such method.
People also have out-of-body experiences not related to a near-death episode, or they might have an experience of expanded consciousness which takes them beyond this physical world, and that may not be related to a near-death episode either.
There may even be more but these are at least three that I am aware of, and I am also aware that near-death experiences receive most of the attention by the public in Europe and the Americas, while out-of-body experiences, and cosmic consciousness, may receive more attention elsewhere.
Whether it is an experience of expanded consciousness, commonly called an experience of cosmic consciousness, an out-of body experience, while sitting in meditation, etc., or a near-death experience, they all have the potential of revealing a greater truth about the afterlife.
Whether they are healthy or not depends on how they are handled by the person who experiences them. An while they have a great impact on people’s lives, I think they are not required for growth and development. They are not caused by the brain or body, rather they are caused by a person’s ability to let go of their brain and body. Whether they are planned by the “soul” before birth is a question I cannot answer, but I can say that I do not believe in random events.
"Life is like a box of chocolates." Forrest Gump