Do you believe in life after death?
Many people believe in ghosts and heaven, and about three in 100 Americans report actually having near-death experiences. These typically include an awareness of being dead, out-of-body experiences, meeting dead people, entering tunnels of light, and so on.
But these are stories and anecdotes; what does science have to say?
A new article published in Trends in Cognitive Sciences by neuroscientist Dean Mobbs, of the University of Cambridge's Medical Research Council Cognition and Brain Sciences Unit, and Caroline Watt, of the University of Edinburgh, finds that "contrary to popular belief, research suggests that there is nothing paranormal about these experiences. Instead, near-death experiences are the manifestation of normal brain function gone awry, during a traumatic, and sometimes harmless, event."
Mobbs and Watt noted that many classic NDE symptoms are actually reported by people who were never in danger of dying in the first place. This suggests that the perception that one is near death is traumatic and disturbing enough to cause some of the experiences.
Researcher Susan Blackmore, author of Dying to Live: Near-Death Experiences (Prometheus Books, 1993), notes that many NDEs (such as euphoria and the feeling of moving toward a tunnel of white light) are common symptoms of oxygen deprivation in the brain.
The new paper also discussed something called "walking corpse" syndrome, named after French neurologist Jules Cotard. Co-author Watt told Discovery News, "The sufferer feels that he or she is dead, even though not actually near death. It can be associated with trauma and some illnesses. It's not fully understood why individuals suffer from Cotard syndrome, but one possibility is that it's the brain's attempt to make sense of the strange experiences that the patient is having.
"This is relevant to NDEs because the near-death experience may also arise out of an attempt to interpret unusual physiological and psychological experiences, and the NDE includes the perception that one is not alive in the normal sense of the word."
Watt's research also busts another myth: that people have "returned from the dead" — if by dead you mean clinical brain death.
No one has survived true clinical death (which is why the experiences are called near-death). Many people have been revived after their heart stopped for short periods of time — around 20 minutes or more — but anyone revived from brain death would be permanently and irreparably brain damaged and certainly unable to report their experiences.
"The idea of surviving clinical brain death is mythical," Watt said. "NDEs are sometimes reported after a person experiences some of the preliminary 'stages' of death — for instance, when the heart stops beating for a while and the person is then revived. I think it's curious, however, that a survey has shown that 82 percent of individuals who have survived being actually near death do not report a near-death experience. That would seem to undermine the idea that these experiences give a glimpse into life after death."
Watt believes that near-death experiences hold an enduring fascination for people because they like the idea that humans survive bodily death.
"Some people find this a comforting idea," Watt said, "because it suggests we are not simply like other biological organisms on our planet."
The fact that near-death experiences can be chemically induced and explained by neurological mechanisms suggests a natural — instead of supernatural — cause.