Near Death Experiences
A comparison of the effects of hypoxia to the reports of a brush with the afterlife.
June 7, 2011
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By Brian Dunning, Skeptoid Podcast
Episode 261, June 07, 2011
Today we're going to float around the operating room, look down at our own body lying there on the table, hear the heart monitor switch to a solid tone, and learn first-hand what some believe goes on during a near death experience. When a small percentage of people are near death or are temporarily dead, either from an accident or during emergency lifesaving treatment, they report eerie experiences that they interpret as having crossed the threshold into an afterlife. Some authors and researchers have catalogued these reports and concluded that the experiences must have been real, while some skeptical researchers have found that the experiences are the natural and expected result of low oxygen to the brain. It seems the perfect place to point our skeptical eye.
A favorite starting point when examining such tales is the application of Occam's Razor. This states that the explanation requiring the introduction of the fewest new assumptions about our world is probably the true one; in other words, the explanation that best fits our understanding of the way the world works. The supernatural explanation for near death experiences (NDEs) requires the existence of an afterlife, heaven or hell or whatever you prefer to call it. To science, which has never found any reason to suspect life might continue after the death of the body, such a place would be a major new assumption about our world. But to many people with certain religious beliefs, such a place is a given and the afterlife is real, and is thus not a new assumption. So to a lot of people, Occam's Razor does nothing to settle this particular question.
Probably everyone will agree to some extent that the brain is capable of generating surprising experiences, such as highly realistic dreams. We've all had faint or dizzy spells, and these can be pretty dramatic episodes even though, to an outsider, nothing notable happened physically. A bit later we'll talk about how all of the major events of an NDE are created in the brain in certain experiments. In summary, even those who believe that NDEs truly represent a brush with the afterlife probably agree that every experience that characterizes one can also be attributed to a natural cause. Why, then, is there a tendency to insist that they had to be an actual life after death experience?
In 1975, Dr. Raymond Moody published Life After Life, which became the seminal work promoting NDEs as evidence of an afterlife. Dr. Moody is a strong personal believer in not only the afterlife, but also reincarnation, claiming that he has personally lived nine previous lives. In his books he's cited 150 cases of people who, after resuscitation, reported extraordinary experiences.
Let's take a look at the reports. First, the basics. Although it's rare for any two stories to be substantially similar, there are common themes. One the most familiar is the life flashing before the eyes, a quick fast-forward replay of either the entire life or important events, even long-forgotten events, commonly called a life review. Perhaps the most popular report is a bright light, warm and inviting. Sometimes this is combined with a feeling of floating through a tunnel. Some NDEs include an out-of-body experience, usually floating in the air and seeing one's own body below, being tended to by medics, sometimes reporting seeing things happen that could not have been observed from the body's position. People with physical limitations, blind, deaf, or paralyzed, usually find that their bodies are whole during these experiences.
Some people report positive meetings with deceased loved ones or religious figures such as Jesus or Muhammad. Just as often, however, people report terrifying encounters with monsters, hated people, or the devil. So while many experiences are euphoric, many are very much the opposite.
So the question is, can we group all of these things together in such a way as to find an undeniable pattern? Is there enough consistency and predictability that we can conclude with good certainty that such a thing as an afterlife must exist, and here is the probable experience you'll have as you cross over? It's unlikely. When Skeptoid looked at The Hum, a worldwide acoustic phenomenon, we found enough variation to conclude that there are probable many different causes that likely have nothing to do with each other. NDEs are similarly complicated by many unrelated causes of characteristic experiences: drug effects, hypoxia, trauma, brain abnormalities, and simple dreaming, just to name a few. We'd expect people coming out of all these conditions to report things very similar to NDEs.
Let's take a look at out-of-body experiences. You can search the Internet and you'll easily find dozens (if not more) stories where someone floated off the operating table and made observations about the room, actions performed by surgical staff, and even things happening outside the room. I'm not even going to list them because there are so many, and I'll grant that many of them sound undeniable, that the only possible explanation is that the person's consciousness and perspective was indeed outside the body. Having read a lot of these, I make three observations:
1. I know a number of anesthesiologists. They are not impressed by these stories. It is common for patients to be aware during general anesthesia. They remember many details of the people, objects, and procedures in the room. We absolutely expect some number of supposedly unconscious patients to report things that happened that a layperson would assume were unknowable. In fact, The Lancet published research in 2001 that showed nearly 20% of patients retained memories of things that happened when they were clinically dead.
2. What's rarely or never written up in books is the fact that most such "recollections" get their details wrong, and were probably just imagined by the patient. When authors compile stories to promote the idea of NDEs, they tend to universally exclude these; in fact the majority were never recorded anywhere to begin with. If out-of-body experiences are truly part of passing over into the afterlife, then they usually represent an afterlife of some alternate universe where everything's wrong.
3. Some of the stories can't be explained by either of the above. They include specific details that the patient could not have known. Sadly, all of these are anecdotal. They're very interesting and I wish we had more of them, and that controls had been in place at the time. Since they weren't, the scientific method requires us to shrug and say "Neat, but not evidence, let's do it better next time."
As an example of the value of anecdotes in suggesting directions for research, Dr. Penny Sartori placed playing cards in obvious places on top of operating room cabinets at a hospital in Wales in 2001, while she was working as a nurse, as part of a supervised experiment. Although she's a believer in the afterlife, and documented fifteen cases of reported out-of-body experiences by patients during her research, not one person ever reported seeing the playing cards or even knowing they were there.
Life review, euphoria, bright lights, and meetings with sacred personages have all been correlated with high levels of carbon dioxide in the brain. Research published in the journal Critical Care in 2010 found that over one-fifth of heart attack patients who went into cardiac arrest and were resuscitated, all of whom would have had high CO2, reported these phenomena. But these patients were all also nearly dead; so the NDE correlates equally well with being near death as it does with the physiological condition. To find out which is the best correlation, we'd have to see whether an NDE can happen when one condition is present and the other is not.
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.
What about the reverse? Are there reliably documented reports of NDEs from people who were near death, but whose brains had normal oxygen supplies? If there are, I was not able to locate any. This leaves only one group of conditions that can be consistently correlated with what we call a near death experience, and it's not nearness to death. It's a set of brain conditions that includes hypoxia, hypercarbia, and anoxia.
Other researchers have also found ways to produce the symptoms of a NDE without nearness to death being a factor. In 1996, Dr. Karl Jansen published his successful results of inducing a NDE using the drug ketamine. In 2002, Nature published research in which experimenters gave direct electrical stimulation to the part of the brain called the angular gyrus in the parietal lobe. Subjects reported being able to see themselves lying there from a vantage point near the ceiling, and were able to communicate what they observed as it was happening. Some brain surgeries, most notably those for epilepsy, produce very high rates of NDE reports from patients whose lives were not in danger.
But believers in the afterlife are quick to point out that just because the reported experiences have natural explanations, it doesn't prove that the supernatural explanation is not also true in at least some of the cases. That's true, of course. We'd love to have such proof. Most of the symptoms of NDEs, like seeing a bright light and feeling euphoric, are too vague to serve as proof of the afterlife. But one isn't, and that's the out-of-body experience. What science would love to find is a win in a controlled test, consisting of the disembodied consciousness successfully completing a task under controlled conditions. If the claims of the most interesting such stories are true, this should not be a problem. It hasn't happened yet — nobody's yet seen Dr. Sartori's hidden cards, or beaten any other similar tests — but here's to hoping that they do. We all hope that death is not the end. Perhaps someday someone will prove Raymond Moody right, and we can all look forward to a catlike nine lives.
© 2011 Skeptoid Media, Inc.
References & Further Reading
Blackmore, S. "A Psychological Theory of the Out of Body Experience." Journal of Parapsychology. 1 Sep. 1984, Volume 48, Number 3: 201-218.
Blanke, O., Ortigue, S., Landis, T., Seeck, M. "Stimulating illusory own-body perceptions." Nature. 3 Oct. 2002, Volume 419: 269-270.
Braithwaite, J. "Towards a Cognitive Neuroscience of the Dying Brain." The Skeptic. 1 Jul. 2008, Volume 21, Number 2.
Jansen, K. "Using ketamine to induce the near death experience: Mechanism of action and therapeutic potential." Yearbook for Ethnomedicine and the Study of Consciousness. 1 Jan. 1995, Issue 4: 55-81.
Kruszelnicki, K. "Near-death myth alive and kicking." ABC Science. Australian Broadcasting Corporation, 8 Mar. 2007. Web. 3 Jun. 2011. <http://www.abc.net.au/science/articles/2007/03/08/1866095.htm>
Moody, R. Coming Back: A Psychiatrist Explores Past-Life Journeys. New York: Bantam Books, 1991. 11-28.
Van Lommel, P., Van Wees, R., Meyers, V., Elfferich, I. "Near-death experience in survivors of cardiac arrest: A prospective study in the Netherlands." The Lancet. 15 Dec. 2001, Volume 358: 2039-2045.
Whinnery, J., Whinnery, A. "Acceleration-Induced Loss of Consciousness: A Review of 500 Episodes." Archives of Neurology. 1 Jul. 1990, Volume 47, Number 7: 764-776.
Reference this article:
Dunning, B. "Near Death Experiences." Skeptoid Podcast. Skeptoid Media, Inc., 7 Jun 2011. Web. 23 Jul 2014. <http://skeptoid.com/episodes/4261>