Near-death experience
A near death experience (NDE) is the sensation of an out of body experience reported by a person who nearly died or who was clinically dead and revived. They are somewhat common, especially after the development of cardiac resuscitatation techniques, and are reported in approximately one-fifth of persons who experience clinical death.
Typically a near death experience involves the sensation of floating above one's body and seeing the surrounding area, followed by the sensation of passing through a tunnel, meeting departed relatives, and encountering a being of light.
Although near death experiences have been taken as evidence of an afterlife, it has been pointed out that there are no known elements of near death experiences which cannot be explained in natural terms. In particular, it has been pointed out that children who experience NDE's sometimes report seeing their living friends and playmates in their visions. In a addition, there have been numerous experiments in which a random message was placed in a hospital in a manner that it would be invisible to patients or staff yet visible to a floating being, and thus far, no person experiencing a near death experience has been able to reproduce the message. However, there have also been accounts of patients seeing things they could not have seen had they not been out of their bodies.
Somebody please check the following paragraph, my memory of the subject is a little fuzzy, but I'm certain that the basic idea is right.
There was also a drug used as an anesthetic on U.S. soldiers during the Vietnam War that was abandoned and never spread to civilian use because the soldiers complained about sensations of floating above their body and seeing bright lights. It turns out that the anesthetic mimics a neurotransmitter released when brain cells start dying that prevents the dying cells from causing other cells to die.
Dr. Raymond Moody has chronicled and studied many of these experiences in his books:
Another researcher in the field is Dr. Kenneth Ring.
See: