Near-death experience

A near-death experience may refer to anything experienced over the course of clinical death and subsequent recovery. It usually implies a spiritual ordeal of some kind, such as an out-of-body experience, and is often cited by believers as "evidence" for the existence of an afterlife.

In the broadest sense of the term, a near-death experience (NDE) may be brought about by coma, serious accident, dreaming, drugs, stress, surgery, seizure, sudden oxygen deprivation, brain stimulation, or orgasm. Around 3 percent of Americans report experiencing some type of NDE.

Elements
There exist no "research diagnostic criteria" for NDEs as there are for other psychiatric disorders. Thus, researchers often find themselves in disagreement as to whether a collection of phenomena constitutes a NDE, and struggle to ascribe causal factors to any given experience.

Psychologist and copromancer Raymond A. Moody, Jr. coined the phrase "near-death experience" in Life After Life (1975) and established a composite experience based on testimonials. Experiences vary, and a typical NDE will include one or more elements.

Claimed experiencers of them have described NDEs as a transcendent mystical state. They reported sensing all-encompassing love, beauty, and peace, contentment, timelessness, and painlessness. Some perceived that they had access to unlimited knowledge. This knowledge cannot be reproduced, suggesting the experience is illusory. Many explained that the experience was beyond words. In contrast, some have had frightening visions.

According to a study by Pim van Lommel and others, 50% of NDE'ers reported an awareness that they were dead. Many admitted that the NDE seemed "real," and although it is common to experience an extreme clarity of thought, still others reported feelings of disorientation.

According to van Lommel, 31% of NDE'ers reported passing rapidly through a transitional world of dark tunnels in what is sometimes referred to as "the tunnel experience." Often they then emerged into a light at the end of the tunnel.

It is common for NDE'ers to report the perception of a presence that they believed to be God or some other spiritually neutral entity or to perceive God as light and to engage in telepathic communication with God or Christ. According to van Lommel, 32% reported meeting with deceased persons, especially loved ones, with which telepathic communication might occur. NDE'ers have also seen images of (usually) helpful people, landscapes, religious or mythical figures (such as angels), celebrities, or fictional characters. According to a study by Peter and Elizabeth Fenwick, 14% of NDE'ers reported encountering living persons. Some recalled hearing specific sounds.

A NDE may include a "life review," or the emergence of memories into consciousness, apparently in order to be relived or judged. According to the Fenwicks, 15% of NDEs included recalled memories, although only half of memories were deemed to be significant.

Some NDE'ers recalled a desire not to leave their body and making the decision to return to it. According to van Lommel, 8% reported a threshold crossing or "point of no return" beyond which they felt they would be unable to return to life. However, some crossed this threshold and managed to return anyway. Additionally, a portion of NDE'ers reported feeling a detachment from the body or even seeing their physical body during an out-of-body experience (OBE).

Finally, a significant number of NDE'ers indicated that the experience had a life-changing effect on them. Additionally, there have been reports that NDE'ers have problems making watches stop, look younger, and gain psychic abilities, healing powers, or prophetic visions afterward, although none of these effects have been substantiated.

Scientific explanation
Every night, I talk to dead people and I fly through space, and I call it dreaming. The relative similarities of NDE accounts imply a biological origin. Viewed as a scientific phenomenon, the NDE is of some interest to medicine and psychiatry. Hypotheses advanced by researchers include neurochemical as well as psychological explanations. Obviously, the calming effects of NDEs would have physical as well as emotional benefits to an individual who was close to dying.

Aspects of NDEs indicate that the temporal lobe is involved. The temporoparietal lobe is the area in which the brain locates itself in space — that is, behind the eyes. Co-ordination between the organs necessary for interaction with the outside world — limbs, sensory organs and of course the brain — is vital for our survival, and the brain must locate the body's organs (mistakes in doing this could be the cause of phantom and alien limb syndromes) and itself in order for this to work. Electrical stimulation of the temporoparietal lobe has been shown to reliably induce the same dissociation found in NDEs and OBEs. Out-of-body experiences can also occur during episodes of fainting or extreme physical exhaustion such as hiking at high altitude. Additionally, some of the elements of NDEs can be reproduced with anesthetics. Kevin Nelson suggests that the common factor in all these experiences is reduced oxygen supply to the brain, which shuts down region by region in such circumstances to conserve energy. When the oxygen supply to the temporoparietal lobe is cut off, this would trigger an out-of-body experience. It should be mentioned that the temporal lobe, which is near structures such as the hippocampus and amygdala, is heavily involved in the storage of memory; temporal lobe epilepsy (a localized form of the common seizure disorder) often involves sensory hallucinations of various kinds and memory disturbances. Furthermore, as the brain dies, the brain releases most of its serotonin, the "feel-happy" hormone, which would create a sense of euphoria.

NDEers have been associated with a rather specific psychological profile including sleep/dream patterns and positive coping styles. The tendency for individuals to experience OBEs can be predicted by somatoform dissociation, the failure to process somatic experiences. The astronomer Carl Sagan suggested that common NDE elements such as tunneling, light, and telepathic communion with a god may be a reactivation of birth memories.

Some elements of NDEs may represent the incorporation of stimuli sensed subconsciously, for example via "anesthesia awareness" during surgery. The ability to later describe events taking place during an OBE may be the result of easy guesses or leading questions or unintentional information given by the interviewer. Keith Augustine quotes Dr. Susan Blackmore that "'prior knowledge, fantasy and lucky guesses and the remaining operating senses of hearing and touch,' plus 'the way memory works to recall accurate items and forget the wrong ones' is sufficient to explain out-of-body imagery in NDEs."

Testimonials may reflect what one has heard or expects based on the testimonials of others. In addition, NDE research suffers from the "file-drawer problem," cherry picking only those testimonials that help advance the researcher's hypothesis, and ignoring the fact that most instances of being near-death are not accompanied by any NDEs.

Computational psychology experiments conducted by S. L. Thaler in 1993 using artificial neural networks have shown that many aspects of the core near-death experience can be achieved through simulated neuron death and synaptic disruption. In the course of such simulations, the essential features of the NDE—life review, novel scenarios (e.g., heaven or hell) and OBE are observed through the spontaneous generation of both true and false memories at first driven by synaptic fluctuations due to excess stress neurotransmitters such as adrenaline. In later stages of the NDE, confabulatory states result from a neural network's inability to differentiate dead from silent neurons. Memory-like neural activation patterns, whether related to direct experience or not, can be seeded upon arrays of such inactive brain cells, providing a purely mathematical basis for both NDEs and OBEs. In effect, the neural networks of the brain are interpreting their own internal damage, successfully or not, at an ever increasing rate, giving the impression of eternity as attendant neural networks of the cortex become sufficiently damaged that they fail to distinguish the neurologically-induced fantasy from reality. Within this so-called "death dream", the most habituated beliefs and expectations of the individual are played out.

Later, PZ Myers similarly suggested that false memories may be generated as the brain tries to make sense of a time when consciousness did not exist. Further wishful thinking may generate experiences confirming what a subject wants to believe and brain damage may prevent a subject recognizing that the experience was a dream.

Due to the complexity of NDEs, a particular scientific hypothesis of their cause need not explain all possible experiences.

It has also been shown that the brain is still active, but in deep sleep mode, for about 10 minutes after clinical death, and as nobody has come back from more than that, it may just be the final dreams before eternal nothingness.

Ketamine
Based on his research, Dr. Karl Jansen notes that "Recent advances in neuroscience are bringing us closer to a brain-based understanding of the NDE as an altered state of consciousness." Jansen also determined that the effects of an NDE can be induced with ketamine, a hallucinogenic, dissociative anesthetic related to PCP. Jansen explains, "Ketamine administered by intravenous injection is capable of reproducing all of the features of the NDE which have been commonly described."

Regarding ketamine, Jansen quotes Doctors Grinspoon and Bakalar that "The dissociative experiences often seem so genuine that users are not sure that they have not actually left their bodies." Jansen quotes Dr. Leary that ketamine use represents "experiments in voluntary death."

Jansen's explanation of why ketamine and a near-death condition will cause similar effects is summarized as follows:

NMDA receptors in portions of the brain are important in cognitive processing and other functions. The same region of the brain plays a role in epileptic events and others in which cell (neuron) damage may occur due to the presence of glutamate (neurotransmitters). The use of ketamine prevents such damage. The brain might possibly release a neuroprotective counter-flood to glutamate similar to ketamine during catastrophic events. It is known, for example, that endopsychosins and magnesium and zinc ions naturally bind to the same (drug binding) sites as ketamine (the PCP binding site of the NMDA receptor). The hallucinogenic effects of ketamine are due to an NMDA receptor blockade.

Thus Jansen concludes "Near-death experiences (NDEs) can be reproduced by ketamine via blockade of receptors in the brain (the N-methyl-D-aspartate, NMDA receptors) for the neurotransmitter glutamate." Most of this explanation is based on well-understood observations of neurological processes.

When a NDE is induced by ketamine administered by an anesthetist, it is known as "emergence phenomena" or "psychic emergence reaction".

Like NDEs, ketamine use has therapeutic after-effects.

The most common refutation for this is that "natural explanations can still have a supernatural explanation". While this is true, in the same sense that you can be a brain in a vat being fed the experience of a simulated universe, that's called "privileging the hypothesis", especially considering science's impressive track record of giving natural explanations to every other phenomenon that was once considered supernatural. Even if we assume the supernatural is real, that still doesn't prove NDEs are real occurences with any specific deity, especially since people who claim to see gods, by an amazing coincidence, typically report seeing the ones they believe in.

Evidence of afterlife
NDEs and especially OBEs are cited as evidence of disembodied spirits, separate consciousness, and, therefore, life after death. Proponents claim the consistency of testimonials and the life-changing effects indicate that NDEs are real. Since by definition an NDE is a "subjective experience", such experiences are also by definition non-repeatable and non-provable, though not necessarily erroneous. Thus, debating with an NDE'er about the accuracy of his or her experience sometimes becomes an exercise in futility.

Additionally, subjects' testimonials of clarity of thought is presented as evidence of the reality of NDEs. However, consider Jansen's finding that "...30% of normal subjects given ketamine were certain that they had not been dreaming or hallucinating, but that the events had really happened." By its definition, a hallucination seems real. In fact, drunk drivers commonly admit perceiving clarity of thought. Jansen asserts, "A personal conviction of the 'reality' of an NDE does not invalidate scientific explanations."

The explanation that NDEs are in fact passage into the afterlife presents several contradictions. Jansen quotes Dr. Melvin Morse that "One of the many contradictions which 'after-lifers' can not resolve is that 'the spirit rises out of the body leaving the brain behind, but somehow still incorporating neuronal functions such as sight, hearing, and proprioception.'" Such a separation of the "spirit" and the brain ignores scientific evidence that indicates consciousness is dependent on the brain.

Also consider that at times living persons are encountered in NDEs. If NDEs were real, then expecting to see living persons there would be as reasonable as expecting the persons one sees in dreams to actually be there.

Religious figures encountered in NDEs appear as they are commonly depicted, although trends vary by culture. In other words, one sees what one expects to see. Additionally, historical accounts differ from the typical Western NDE.

There are discrepancies documented in patient descriptions compared to actual events during OBEs. Additionally, experiments designed to confirm OBEs have all ended in failure.

It appears that the theme of a threshold occurs in NDEs because subjects are seeking a rationale for why they were sent back from the afterlife. However, sometimes the choice is made to cross the threshold, and yet the NDE'er returns to the living world nonetheless.

Finally, it is not clear why only a percentage of subjects coming close to dying report having NDEs.

Afterlife proponents point out that NDEs occur during a period of no measurable brain activity. However, this excludes the possibility of the experience occurring during immeasurable brain activity or, more likely, upon waking. In fact, the observation that the experience was remembered implies that the brain was working at the time.

Rene Jorgensen, who concludes through the evidence of testimonials that NDEs are evidence of an afterlife, admits that "...people who have been brought back from the other side are the most reliable sources of information about life after death", which means that the evidence is anecdotal.

Note that many people who have an NDE do not actually die, and their experiences cannot be taken as direct evidence of an afterlife. Even some proponents agree that NDEs do not represent evidence of an afterlife. Similarly, a brain-based explanation of NDE need not be taken as evidence against life after death, although this argument is fairly devoid of usefulness.

As Fan-fiction
While visions of the afterlife tend to thankfully remain relatively obscure throughout the mainstream, throughout Christian circles, visions are a booming industry for anyone who wants their 15 minutes of fame, or a quick buck. Thanks to Web 2.0, and millions of websites hosting galleries of these testimonies alone, from teenagers who want attention, to parents who want to publicize their child, can upload their testimonies online, and watch the view count rise. Their stories tend to stick around for years to come, as plagiarizers re-upload long-deleted videos. These "testimonies" are usually designed to be as diabetes-tasting as possible while describing heaven, to reassure believers, and as sadistic as possible while describing Hell, to scare non-believers into converting. Creativity? Who cares? Just invent all sorts of saccharine visions and sadistic torture methods, and you could be the next witness to the credulous faithful.

There are many NDE books that claim to recount true experiences or 'prove' the existence of religious figures. Titles like Heaven Is for Real 'prove' the existence of God in the eyes of an NDE patient who claims to have seen God, his miscarried sister, and his deceased grandfather whom he never met, all in heaven. It eventually made its way to live television, and became a movie that grossed over US$97 million. Of course, one person said so, so it must be right!

Other books that some people consider to be 'proof' of their god/s are:
 * 90 Minutes in Heaven (ISBN 0800759494), about a man who is 'dead' for 90 minutes after a car crash and in that time, enters heaven — a suspiciously Evangelical heaven, for that matter.
 * Saved by the Light (ISBN 0061008893), a story of a man who receives revelations of a nuclear accident in Norway, the collapse of the US economy before the 2000s, and that the US would be destroyed by earthquakes from 'figures of light'. Perhaps we missed something over the past decade, but we don't seem to recall any of that coming true.
 * Embraced by the Light (ISBN 0553565915), a story of an LDS woman who dies on the operating table, goes to heaven, and comes back. It's actually fairly moving.
 * Heaven Is for Real: This is a four-year-old boy's colorful experience of heaven with rainbow colored horses and the like.
 * Proof of Heaven was written by Eben Alexander about his recollection of a near death experience. It was later disproven by Luke Dittrich during a report that contained various interviews with doctors and meteorologists.
 * The Boy Who Came Back From Heaven is a "true story" about a boy (Alex Malarkey) who visits heaven after a horrific car accident leaves him in a coma and then paralyzed. In 2018, Alex was now 20 years old, and recanted his story about going to Heaven and has sued the Christian publisher, Tyndale House, for royalties. The publisher allegedly continued selling this book (and others) knowing that it was fraudulent. Who knew a Christian publishing house would knowingly continue profiting from a known hoax?

Contradictory information
There are those, however, who have died, and never experienced such natural phenomenons.

I can hear everything around me and feel as though I'm trying to shout out but nothing is coming out. They say when you die your hearing is the last thing to go and that's been my experience. There is definitely no bright light. Everything just goes black. - Sara Brautigam
 * Sara Brautigam - a young woman who has died 36 times in 1 year, due to her condition called postural orthostatic tachycardia syndrome.