Frightening or Unpleasant Near-Death Experiences

I am currently preparing a paper about frightening near-death experiences to present at a forthcoming conference. (I’ll post a future comment with links to the conference over the next few days). I am very interested in the frightening NDEs as well as the pleasant NDEs. However, there is far less information about the frightening NDEs so I am looking for people who have specifically experienced a frightening NDE.