Some would argue that its the brain firing off before it dies and that nde's are a phenomenon of a brain dying.
However, there are DE's that go far beyond near death experience into the realm of death experience. This is where someone has been dead for a an hour or more and then miraculously comes back to life.
Mellon Thomas is such an account.
I find it much easier for people to try and explain away things that there is no scientific measurement of...YET!