Martin Adams,, CC0 Licensing
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Yesterday, I introduced the topic of Near-Death Experiences (NDEs), and today I will talk about naturalistic, scientific explanations for such phenomena.

The problem with scientific explanations and hypotheses for such phenomena is that they aren’t as fun and exciting as some funky spiritual world operating in parallel, or whatever NDErs believe. This rather less romantic appeal to empirical data and chemicals and brains means that, to many, such skeptical explanations are less appealing, and so are less persuasive.

We are emotional and intuitive beings before we are rational beings.

So here are some very short summaries of hypotheses and research findings.

Oxygen shortage

Hypoxia, or oxygen shortage, is a common result of cardiac arrest, and this can lead to many strange experiences such as hallucinations, confusion and disorientation. Steven Novella, neuroscientist and skeptic, states:

Neuroscientists are piecing together plausible explanations for each of the components of the NDE. The sensation of floating outside one’s body can be reliably induced by suppressing that part of the brain that makes us feel as if we possess our bodies. The experience is identical to that reported by those who have had an NDE. This experience can be replicated by drugs or magnetic stimulation. There are even reports (I have had one such patient) of people who have a typical NDE experience during seizures. The bright light can be explained as a function of hypoxia (relative lack of oxygen) either to the retina or the visual cortex. Any everything else [?] is simply the culturally appropriate hallucinations of a hypoxic brain….

Severe brain malfunction

According to Engmann (2008) near-death experiences of people who are clinically dead are psychopathological symptoms caused by a severe malfunction of the brain resulting from the cessation of cerebral blood circulation.[80] An important question is whether it is possible to “translate” the bloomy experiences of the reanimated survivors into psychopathologically basic phenomena, e.g. acoasms (nonverbal auditory hallucinations), central narrowing of the visual field, autoscopia, visual hallucinations, activation of limbic and memory structures according to Moody’s stages. The symptoms suppose a primary affliction of the occipital and temporal cortices under clinical death. This basis could be congruent with the thesis of pathoclisis—the inclination of special parts of the brain to be the first to be damaged in case of disease, lack of oxygen, or malnutrition—established eighty years ago by Cécile and Oskar Vogt.[81][source]

G-force induced Loss Of Consciousness

Whinnery (1997) revealed the similarities between NDEs and G-LOC (G-force induced Loss Of Consciousness) episodes.[75] Based on the observations of G-LOC, Whinnery noted how the experiences often involved “tunnel vision and bright lights, floating sensations, automatic movement, autoscopy, OBEs, not wanting to be disturbed, paralysis, vivid dreamlets of beautiful places, pleasurable sensations, psychological alterations of euphoria and dissociation, inclusion of friends and family, inclusion of prior memories and thoughts, the experience being very memorable (when it can be remembered), confabulation, and a strong urge to understand the experience.”[75][source]


The use of ketamine has been shown to have the same effects as NDEs, such as in Karl Jansen’s Using ketamine to induce the near-death experience: mechanism of action and therapeutic potential, amongst others. In that, he claims, “mounting evidence suggests that the reproduction/induction of NDE’s by ketamine is not simply an interesting coincidence… ketamine administered by intravenous injection, in appropriate dosage, is capable of reproducing all of the features of the NDE which have been commonly described in the most cited works in this field.”

Psychedelic drugs

Drugs, such as dimethyltryptamine (DMT), have been shown to produce the same or similar effects as NDEs.


Too much carbon dioxide can also be a problem, and it is claimed it may give a feeling of separation from the body. Indeed:

Research released in 2010 by University of Maribor, Slovenia had put near-death experiences down to high levels of carbon dioxide in the blood altering the chemical balance of the brain and tricking it into ‘seeing’ things.[88] Of the 52 patients, 11 reported NDEs.[89][90]

Temporoparietal junction

A glitch in this part of the brain can lead to problems. The Atlantic claims it is:

a part of the brain that acts as a kind of integrator of data from all your senses and organs and plays an important role in assembling them into your overall perception of your body, can produce an out-of-body experience.

As wiki states:

Vanhaudenhuyse et al. 2009 reported that recent studies employing deep brain stimulation and neuroimaging have demonstrated that out-of-body experiences result from a deficient multisensory integration at the temporoparietal junction and that ongoing studies aim to further identify the functional neuroanatomy of near-death experiences by means of standardized EEG recordings.[86]

…NDE subjects have increased activity in the left temporal lobe.[3] Stimulation of the temporal lobe is known to induce hallucinations, out-of-body experiences and memory flashbacks.[91] In an experiment with one patient, electrical stimulation at the left temporoparietal junction lead to an illusion of another person being close to her.[92][93]Chris French has written that the “temporal lobe is almost certain to be involved in NDEs, given that both damage to and direct cortical stimulation of this area are known to produce a number of experiences corresponding to those of the NDE, including OBEs, hallucinations, and memory flashbacks.”[62]

Seratonin levels

Again, over to wiki:

In 2011, Alexander Wutzler and his colleagues at the Charité University of Medicine in Berlin, Germany suggested that near-death experiences may be triggered by an increase of serotonin in the brain.[94][95] Charles Q. Choi in an article for the Scientific American concluded “scientific evidence suggests that all features of the near-death experience have some basis in normal brain function gone awry.”[96]

Oneiroid syndrome

This is an element of the catatonic form of schizophrenia and presents with a dream-like or nightmare-like state as a background of intensive psychopathological experiences. A 2012 study led by neuroradiologist Renemane “reached the conclusion that the NDE is a state of unconsciousness resembling oneiroid syndrome.[97]” [wiki]

Oh, rats!

There is one newish bit of research that the materialist camp has seized on. A study at the University of Michigan, published in 2013, took anesthetized rats and stopped their hearts. Within 30 seconds, the rats’ EEG brain signals flatlined—but first they spiked, with an intensity that suggested that different parts of the brain were communicating with one another even more actively than when the rats were awake.

This sort of communication is thought to be a key step in perception; effectively, the brain’s various areas are comparing notes on the stimuli they’re getting. If humans experience the same death spike as rats, it may mean that the brain goes into a final, hyperactive spasm when its oxygen supply is cut as it tries to figure out what is happening. If so, that heightened activity might explain why people who say they had an NDE report that what they experienced seemed more real than the physical world. [source]

I could go on; there are many various claims. Indeed, there is every chance that people could get such experiences from different brain an body events, or a combination. But these claims don’t invite universal appeal:

Doctors who are sympathetic to experiencers’ claims have no shortage of rebuttals to these materialist explanations. Sam Parnia, Pim van Lommel, and others devote lengthy sections in their books to them. Ultimately, what the rebuttals boil down to is that while these explanations may look plausible, there’s no evidence that they actually do explain what’s going on. Many NDEs happen without one or another of the above scientifically measurable conditions. And those conditions often happen without an NDE. Enough data simply haven’t been recorded to establish correlation, let alone causation.

As mentioned in the previous piece, however, it is hard to conceive of methodologies and pragmatic scenarios where there could be enough data.  There are many pieces to this jigsaw, but no complete picture, and perhaps no way of getting a complete picture. As such, the debate will probably rage for decades to come. And yet, for me, it is likely naturalistic in explanation.

Probabilities and naturalism

Using probabilities, as I have set out countless times before, the skeptical, scientific, naturalistic explanations are by far the most likely.

The argument, which includes Lowder’s Argument from the History of Science, can be illustrated as follows, by Richard Carrier, who states:

The cause of lightning was once thought to be God’s wrath, but turned out to be the unintelligent outcome of mindless natural forces. We once thought an intelligent being must have arranged and maintained the amazingly ordered motions of the solar system, but now we know it’s all the inevitable outcome of mindless natural forces. Disease was once thought to be the mischief of supernatural demons, but now we know that tiny, unintelligent organisms are the cause, which reproduce and infect us according to mindless natural forces. In case after case, without exception, the trend has been to find that purely natural causes underlie any phenomena. Not once has the cause of anything turned out to really be God’s wrath or intelligent meddling, or demonic mischief, or anything supernatural at all. The collective weight of these observations is enormous: supernaturalism has been tested at least a million times and has always lost; naturalism has been tested at least a million times and has always won. A horse that runs a million races and never loses is about to run yet another race with a horse that has lost every single one of the million races it has run. Which horse should we bet on? The answer is obvious.

Lowder, in the intro to the formulation of his argument, states:

If there is a single theme unifying the history of science, it is that naturalistic explanations work. The history of science contains numerous examples of naturalistic explanations replacing supernatural ones and no examples of supernatural explanations replacing naturalistic ones. Indeed, naturalistic explanations have been so successful that even most scientific theists concede that supernatural explanations are, in general, implausible, even on the assumption that theism is true. Such explanatory success is antecedently more likely on naturalism–which entails that all supernaturalistic explanations are false–than it is on theism. Thus the history of science is some evidence for naturalism and against theism.

Read more here.

Whether the science that is taking place now has conclusive or inconclusive results is irrelevant when we concern ourselves with what the probabilities are. It is worth remembering here that the human brain is the most complex thing in the known universe. That we may have sensations of being outside of our bodies is not really conceptually beyond the remit or ability of said entity.

In The Atlantic article, there is a fascinating quote concerning a more rational attendee of a conference on NDEs, full of NDErs, and those skeptical of science.

Liester, a tall, craggily handsome psychiatrist who trained at the University of Colorado and the University of California at Irvine, has a gentle, accepting manner that makes you want to tell him everything. His medical training made him skeptical about near-death experiences, he told me. But while he was in school his grandfather had one, and then he kept on meeting other experiencers—not always patients. “People just began talking to me.”

Liester also allowed that he himself had had a “near-death-like experience”—something with the features of an NDE, though he wasn’t near death or on any hallucinogens when it happened. So, I asked him, where does he himself stand on the idea that mind and body are separate?

“My rational brain doesn’t quite believe it but, having experienced it, I know it’s true. So it’s an ongoing discussion I’m having with myself.”

Is there a middle ground, I asked, between the spiritualists and the materialists? It’s hard to find one, he conceded. “A lot of materialist scientists don’t seem to think it’s a serious field of scientific inquiry … Meanwhile, many people who’ve had near-death experiences aren’t that interested in the science.”

Every Monday, Liester has breakfast with a small, eclectic group. It includes a physicist, a materials scientist, an artist, a chaplain with a philosophy degree, and a hospice counselor who is also a Native American sun dancer. They talk about how to take NDE research forward with a rigorous scientific attitude but an open mind. “I think there is a way to bridge the gap,” he said.

In our conversation and in a subsequent e-mail, Liester outlined a few areas that researchers might pursue more deeply. They could image the brains of people while they’re in trances or other “transcendental” states. They could study people who claim special spiritual powers, such as shamans. They could try to probe the nature of the memories formed during NDEs, and how they differ from ordinary memories (Liester is working on this). They could devise experimentally sound ways to test the claims of people who say they have become sensitive to electromagnetic fields or can interfere with electronic devices. They could do more research into the death spike that the University of Michigan researchers found in rats, and perhaps even attempt to isolate it in human patients. And so on.

Above all, he said, no matter how you explain them, near-death experiences are pivotal events in people’s lives. “It’s a catalyst for growth on many different levels—psychologically, emotionally, maybe even physiologically.” [my emphasis]

There’s a lot to unpick there, psychologically. I think what pervades is this overriding desire for NDErs, in a pretty identical manner to conspiracy theorists, for their theory to be true. It’s mixing the excitement, romanticism and iconoclasm of believing in this dualistic and spiritual account of reality that is so much more attractive to them. Probabilities count for nowt.

In conclusion

So whatever happens in the dying brain, I am pretty sure it has the potential, when the variables are right, to be, or at least feel, pretty damned impressive.

To finish off, and to exemplify this, I will bring into play sleep paralysis. I have had this twice. My sister had it for years. This is where your body is asleep but your mind wakes up. You cannot move a muscle, and so have a deep paralysis. This often happens together with hallucinations and the feeling of dread and fear. This phenomena has even been written into cultural mythology in some parts of the world.

As wiki states:

Sleep paralysis is a phenomenon in which a person either during falling asleep (hypnagogia) or awakening (hypnopompia), temporarily experiences an inability to move, speak, or react.

It is a transitional state between wakefulness and sleep, characterized by muscle atonia (muscle weakness). It is often accompanied by unusually powerful and terrifying hallucinations to which one is unable to react due to paralysis, and physical experiences (such as strong current running through the upper body). These hallucinations often involve a person or supernatural creature suffocating or terrifying the individual, accompanied by a feeling of pressure on one’s chest and difficulty breathing. Another common hallucination type involves intruders (human or supernatural) entering one’s room or lurking outside one’s window, accompanied by a feeling of dread.

One hypothesis is that it results from disrupted REM sleep, which normally induces complete muscle atonia to prevent sleepers from acting out their dreams. Genetics and sleep deprivation are a major cause of sleep paralysis,[1] and it has also been linked to disorders such as narcolepsy, migraines, anxiety disorders, and obstructive sleep apnea.[2][3] Sleeping in a fixed supine position increases the chance of sleep paralysis.

I have, in a dorm in a backpackers in New Zealand, felt terror like I had never felt, and saw a host of ghouls parade through the room and out of the window. I couldn’t move, just my eyes.

Is this really that far removed from NDEs? No. No, not at all. Do I believe there is actually a realm of ghouls out there, normally beyond my sight, that I just happened to glimpse?

No. No, not at all.

Brain’s a funny thing.

The probabilities here, they lie with a naturalistic explanation, until the evidence really does support me thinking otherwise. That has not yet come to pass. Nor do I thin it ever will.

Just a hunch.

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Jonathan MS Pearce

A TIPPLING PHILOSOPHER Jonathan MS Pearce is a philosopher, author, columnist, and public speaker with an interest in writing about almost anything, from skepticism to science, politics, and morality,...