People who have these near-death experiences often describe leaving their bodies and watching themselves being resuscitated from above, but verifying such accounts is difficult. The images would be visible only to people who had done that.
"We've added these images as objective markers," says Sam Parnia, a critical-care physician and lead investigator of the study, which hopes to include 1,500 resuscitated patients. Dr. Parnia declined to say whether any have accurately described the images so far, but says he hopes to report preliminary results next year.
The study, coordinated by Southampton University's School of Medicine in England, is one of the latest and largest scientific efforts to understand the mystery of near-death experiences.
At least 15 million American adults say they have had a near-death experience, according to a 1997 survey—and the number is thought to be rising with increasingly sophisticated resuscitation techniques.
- About 75% included an out-of-body experience
- 76% reported intense positive emotions
- 34% described passing through a tunnel
- 65% described encountering a bright light
- 22% had a life review
- 57% encountered deceased relatives or other beings
The once-taboo topic is getting a lot of talk these days. In the new movie "Hereafter," directed by Clint Eastwood, a French journalist is haunted by what she experienced while nearly drowning in a tsunami. A spate of new books details other cases and variations on the theme.
Yet the fundamental debate rages on: Are these glimpses of an afterlife, are they hallucinations or are they the random firings of an oxygen-starved brain?
"There are always skeptics, but there are millions of 'experiencers' who know what happened to them, and they don't care what anybody else says," says Diane Corcoran, president of the International Association for Near-Death Studies, a nonprofit group in Durham, N.C. The organization publishes the Journal of Near-Death Studies and maintains support groups in 47 states.
Dr. Corcoran, a retired Army colonel who heard wounded soldiers talk of such experiences as a nurse in Vietnam, says many military veterans have had near-death experiences but are particularly hesitant to talk them for fear of being branded psychologically disturbed.
Some investigators say the most remarkable thing about near-death reports is that the core elements are the same, among people of all cultures, races, religions and age groups, including children as young as 3 years old.
In his new book, "Evidence of the Afterlife," Jeffrey Long, a radiation oncologist in Louisiana, analyzes 613 cases reported on the website of his Near Death Research Foundation and concludes there is only one plausible explanation: "that people have survived death and traveled to another dimension."
Skeptics say there is no way to verify such anecdotal reports—and that many of the experiences can be explained by neurobiological changes in the brain as people die.
In the 1980s, British neuroscientist Susan Blackmore theorized that oxygen deprivation was to blame and noted that fighter pilots also encountered tunnel vision and hallucinations at high altitudes and speeds.
This year, a study of 52 cardiac-arrest patients in Slovenia, published in the Journal of Critical Care, found that the 21% who had near-death experiences also had high blood levels of carbon dioxide, which has been associated with visions, bright lights and out-of-body experiences.
A study of seven dying patients at George Washington University Medical Center, published in the Journal of Palliative Medicine, noted that their brainwaves showed a spurt of electrical activity just before they were pronounced dead. Lead investigator Lakhmir Chawla, an intensive-care physician, notes that the activity started in one part of the brain and spread in a cascade and theorized that it could give patients vivid mental sensations.
Some scientists have speculated that the life review some patients experience could be due to random activation of the dying brain's memory circuits. The sensation of moving down a tunnel could be due to long-buried birth memories suddenly retrieved. The feeling of peace could be endorphins released during extreme stress.
Other researchers say they have produced similar experiences by stimulating neurons in parts of the brain—or by giving patients ketamine, a tranquilizer and sometime party drug.
Yet researchers who have studied near-death experiences note that such experiments tend to produce only fragmentary visions and hallucinations, not the consistent, lucid and detailed accounts of events that many resuscitated patients report. One study found that people who had near-death experiences had higher blood oxygen levels than those who didn't.
Several follow-up studies have found that people undergo profound personality changes after near-death experiences—becoming more altruistic, less materialistic, more intuitive and no longer fearing death. But some do suffer alienation from spouses or friends who don't understand their transformation.
Other relatives understand all too well.
Raymond Moody, who first coined the term near-death experience in his 1975 book "Life After Life," explores the even stranger phenomenon of "shared death experiences" in a new book, "Glimpses of Eternity." He recounts stories of friends, family and even medical personnel who say they also saw the light, the tunnel and accompanied the dying person partway on his or her journey. "It's fairly common among physicians who are called to resuscitate someone they don't know—they say they've seen a spirit or apparition leave the body," says Dr. Moody.
Meanwhile, in his book, "Visions, Trips and Crowds," David Kessler, a veteran writer on grief and dying, reports that hospice patients frequently describe being visited by a deceased relative or having an out-of-body experience weeks before they actually die, a phenomenon called "near-death awareness." While some skeptics dismiss such reports as hallucinations or wishful thinking, hospice workers generally report that the patients are otherwise perfectly lucid—and invariably less afraid of death afterward.
Mr. Kessler says his own father was hopeless and very sad as he was dying. "One day, he had an amazing shift and said, 'Your mother was here—she told me I'd be dying soon and it will be fine—everyone will be there."
Dr. Parnia, currently an assistant professor of critical care at State University of New York, Stony Brook, says verifying out-of-body experiences with pictures on the ceiling is only a small part of his study. He is also hoping to better understand whether consciousness exists apart from the brain and what happens to it when the brain shuts down. In near-death experiences, people report vivid memories, feelings and thought processes even when there is no measurable brain activity.
"The self, the soul, the psyche—throughout history, we've never managed to figure out what it is and how it relates to the body," he says. "This is a very important for science and fascinating for humankind."