Corroborated reports: After the Brain stops
Evidence for NDE’s includes some corroborated reports with some limited scientific means of testing and systemising them. We have 4 types of evidence we will use in this case: Almost dead; post-heart stoppage; Post-brain activity and Loved ones whose death was at the time unknown. 
The third type of evidence is when NDE’s have been reported during a period when the patient registered an absence of any brain waves. Fred Schoonmaker, a distinguished cardiologist conducted the largest sample of this nature. He managed an 18 year study of 1,400 NDE’s. Included in his analysis were the cases of about 55 patients whose experiences unfolded while having flat EEG readings being recorded, sometimes for periods as long as 30 minutes to 3 hours! Furthermore, the pattern of these experiences fits those of other researchers, and many of the patients reported incidents that were also corroborated by others. 
What’s critical here is how the most vivid memories to these people had were events that happened while their brains registered no known activity. The absence of any EEG brain-wave function is the best and widely accepted indication that the brain is not operative. What is also crucial is that flat brain waves on the EEG, when present over long stretches of time, are the key contemporary definition of the nature of death.  So any ordinary life during these periods of time is strong evidence for life after physical death, that the mind can be independent of the brain and body in general.
Case Study: Woman flat EEG & declared dead
A specific example to meet the above criteria was a woman with Flat EEG, with no vital signs and was declared dead. However, she spontaneously revived about 3½ hours later. And even more shockingly, when she regained consciousness, she lifted the sheet off her face as she was being taken to the morgue by an orderly (That would freak me out!). When giving her report, she described floating over her body during the resuscitation attempts many hours prior, she precisely described details of not only the procedures used in her attempted rescue but also the number of people who came into the hospital room, what they said (which included a joke she could repeat that one of the people told to relieve the tension), and perhaps more intriguingly, she described the doctors’ ties.
All of these claims were rigorously checked with the medical records and the doctors present. It was determined that her whole description was accurate, despite her EEG reading had been flat during that entire time. 
- John Audette, “Denver Cardiologist discloses findings After 18 Years of Near-Death Research,” Anbiosis, vol. 89, no. 1 (1979), pp. 1-2; Dina Ingber, “Visions of An Afterlife,”Science Digest, vol. 89, no. 1 (Jan.-Feb. 1981), pp. 94-97, 142; Gary Habermas had a personal conversation with Fred Schoonmaker, 1 June, 1982
- Exceptions are cases of “drug overdose or extreme hypothermia,” where brain function may not be repressed, See “Definitions of death, Science Digest, vol. 89, no. 1 (Jan.-Feb 1981), p.96; “A Definition of the Irreversible Coma: Report of the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brian Death,” Journal of the American Medical Association, vol. 205 (1968), pp. 337-340.
- Elisabeth Kubler-Ross, “The Experience of Death,” In the Vestibule, ed. Jess Weiss (New York: Pocket Books, 1972), pp. 57-64, pp. 57-64; “when Face to Face with Death,” Readers Digest, (Aug. 1976), p. 84; Cf. “Life After Death?” Newsweek (12 July 1976), p. 41.