Here's another bit about it including the name of the Dr. who conducted the study for the military while I search for the video that I can't seem to find:
It turns out that extensive research has been done to characterize a person's experience with loss of blood to the brain when there is no risk of death, by that patron saint of human experimentation, the US military. For 15 years, Dr. James Whinnery put hundreds of healthy young fighter pilots into centrifuges to understand what a pilot might experience under extreme gravitational loads. He put them in until they blacked out. Once they reached a point where there was inadequate bloodflow to the brain, they lost consciousness; and among the frequently reported experiences were the following: Bright light, floating through a tunnel, out of body experiences, vivid dreams of beautiful places, euphoria, rapid memories of past events, meeting with friends and family, and more. The list is an exact match with the events attributed by believers to a brush with the afterlife.