Near death experiences 'trick of the mind caused by high levels of CO2 in the blood'
By Kate Devlin, Medical Correspondent 7:30AM BST 08 Apr 2010
Now scientists believe they have uncovered the secret behind so-called ‘near death experiences’.
Rather than a religious experience, as many believe, researchers think that the phenomenon could be a simple trick of the mind, caused by a chemical reaction in the body.
People with high levels of carbon dioxide in their bloodstream were more likely to experience the visions, they found.
Previous research suggests that very high levels of the gas can trigger hallucinations in some people.
Many people who have had the experience say that they saw bright lights, a tunnel, or even deceased loved ones beckoning them.
Dr Zalika Klemenc-Ketis, from the University of Maribor, in Slovenia, who led the study, said: “Several theories explaining the mechanisms of near death experiences exist.
“We found that in those patients who experienced the phenomenon, blood carbon dioxide levels were significantly higher than in those who did not”.
"Some earlier studies also showed that inhaled carbon dioxide, used as a psychotherapeutic agent, could cause near death- like experiences.”
She added: “Our study adds new and important information to the field of near death experience phenomena.
“The association with carbon dioxide has never been reported before, and deserves further study”.
Recent studies have shown that high levels of carbon dioxide in the blood can “provoke unusual experiences in the form of bright lights, visions, and out-of-body or even mystical experiences,” according to the findings, published in the journal Critical Care.
The study looked at 52 patients who had suffered a potentially fatal cardiac arrest, in which the heart stops contracting properly.
Of these, 11 reported having a near-death experience at the same time.
Experiencing the sensation was not linked to religious belief, education, drugs administered during their resuscitation, fear of death, gender or age, the study found.
However, they were more common in people who had previously had a near death experience.
Carbon dioxide appears naturally in the blood, carried along in red blood cells, and is used by the body to help regulate blood supply.
During a cardiac arrest carbon dioxide levels usually fall, but a minority of the patients were found to have high levels of the gas in their bloodstream.
Dr Klemenc-Ketis added: "Near-death experiences are a rather unknown but quite common experience in many cardiac arrest patients after successful resuscitation.
"One definition describes NDEs as deep psychological experiences with feelings of transcendence or mystical encounter that typically occur in persons close to death or in situations of intense physical or emotional danger.”
Brain activity shows basis of near-death experiences
Deccan Chronicle - Tuesday, Aug 13, 2013 | Last Update : 06:43 PM IST
Washington, District of Columbia, Aug 13: There may be a scientific explanation for the vivid near-death experiences, such as seeing a shining light, that some people report after surviving a heart attack, US scientists said Monday.
Apparently, the brain keeps on working for up to 30 seconds after blood flow stops, according to a study published in the Proceedings of the National Academy of Sciences.
University of Michigan scientists did their research on nine lab rats that were anesthetized and then subjected to induced cardiac arrest as part of the experiment.
In the first 30 seconds after their hearts were stopped, they all showed a surge of brain activity, observed in electroencephalograms (EEGs) that indicated highly aroused mental states.
"We were surprised by the high levels of activity," said senior author George Mashour, professor of anesthesiology and neurosurgery at the University of Michigan.
"In fact, at near-death, many known electrical signatures of consciousness exceeded levels found in the waking state, suggesting that the brain is capable of well-organized electrical activity during the early stage of clinical death."
Similar results in terms of brain activity were seen in rats that were asphyxiated, the researchers said.
"This study tells us that reduction of oxygen or both oxygen and glucose during cardiac arrest can stimulate brain activity that is characteristic of conscious processing," said lead author Jimo Borjigin.
"It also provides the first scientific framework for the near-death experiences reported by many cardiac arrest survivors."
About 20 percent of people who survive cardiac arrest report having had visions during a period known to doctors as clinical death.
Borjigin said she hopes her team's latest study "will form the foundation for future human studies investigating mental experiences occurring in the dying brain, including seeing light during cardiac arrest."
Mainstream science has long considered the brain to be inactive during this period, and some experts questioned how much a study on rats can truly reveal about the human brain.
"Do we know if animals experience 'consciousness'? Most philosophers and scientists are still at loggerheads over what the term refers to in humans, let alone in other species," said David McGonigle, a lecturer at Cardiff University.
"While recent research now suggests that animals may indeed have the kind of autobiographical memories that humans possess -- the kinds of memories that allow us to place ourselves in a certain time and place -- it seems unlikely that near death experiences would necessarily be similar across species."
nders Sandberg, a research fellow at Oxford University described the research as "simple" and "well-done," but urged caution in interpreting the results.
"EEG tells us things about brain activity a bit like listening at traffic noise tells you what is going on in a city. It is certainly informative, but also an average of a lot of individual interactions," he said.
"No doubt some people will presumptuously claim that this is further evidence for life after death, which is doubly silly. Near-death experiences are in themselves just experiences," he said. "But if one believes that, then one should also conclude the afterlife includes a lot of lab mice."
Is there life after death? As a non-sectarian Buddhist myself, the answer is a big ‘YES’ however doubly silly you may think it is Mr. Sandberg and that includes lots of lab mice as well.
My friend had near death experience before....he was in the hospital and felt his whole body rising up the ceiling....then he warp speed to somekind of heaven and saw a few buddhas....then he heard a deep voice said "your time is not up yet".... then he woke up in the hospital bed feeling complete peace of mind....Was this experience real? Only the believers can tell you....