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One Sunday evening in September, nearly 30 years ago, Xavier Melo, then 23, was driving home from his job as a private math tutor in Barcelona, Spain. It was one of his two weekend jobs, and his car was stacked with study notes and practice tests for an upcoming business school entrance exam. Melo retraced the familiar route home at a leisurely pace, to savor a gentle breeze and the satisfaction of a weekend’s work complete. As he pulled into an intersection, a Volkswagen Golf violently crashed into his car, destroying it. Melo himself suffered head trauma, lost consciousness, and fell into a coma. He woke up in his hospital bed, screaming, again and again, “I have been with God!”

Melo’s memory of the immediate aftermath of the crash is vivid and mysterious; it follows the familiar arc of the near-death experience. He recalls that he flew out of his body and hovered above it, that he observed a nurse in the ambulance who held his hand and called out, “We’re losing him, we’re losing him,” as he watched his papers swirl and scatter in the street. Then he began to rise, the ambulance receding from him in the distance, until he came to a tunnel, where scenes of his life as a child began to play out. He felt an overwhelming sense of belonging, of kinship with the trees, the wind, and the water, and saw an indescribable light that drew him in, a light he began to believe was a being. “It was like the magnetism of love, something that attracts the deepest part of you,” he told me. “I have never been more alive, I have never felt more lucid in my life.” Regaining awareness and sense of his physical body, Melo said, was traumatic.

As Melo relived his story for me over Zoom, from his home in Barcelona, he repeatedly became so overwhelmed with emotion that he had to stop to regain his composure. The experience, he said, transformed him, but not until 25 years after his accident. In 2017, after years in the insurance industry, and upon graduating from a business school program in management, he formed a foundation, Icloby, to promote socially responsible business practices. This fall, the foundation will also embark on a study of near-death experiences in cardiac arrest patients, including children, among Spanish speaking people across Spain, Cuba, Mexico, Colombia, and Argentina. The research project aims to replicate an earlier study of 344 cardiac arrest survivors published in the British medical journal The Lancet in 2001 and led by Pim Van Lommel, a cardiologist, author, and researcher in near-death studies from the Netherlands. “For us, it’s important to demonstrate that death is only for the material body,” said Luján Comas, vice-president of the Icloby foundation, who joined us on the Zoom call.

FREE FALLIN’: You don’t want to undermine someone convinced they had a glimpse of the other side, says neuroscientist Anil Seth. “If they experience flying through a tunnel of light, into a beautiful white open space, then that’s what they experience.” But that experience depends on brain activity. “No brain activity, no mental process.” Image by Fran_kie / Shutterstock.

The idea that near-death experiences, also known as NDEs, offer proof of an afterlife for the soul has been remarkably persistent, despite an accumulation of scientific evidence to the contrary. Such claims have existed in the historical record since at least Plato’s time; the earliest known account of near-death experiences appeared in the fifth century B.C. But they weren’t widely popularized until the 1970s, when American physician and philosopher Raymond Moody published his best-seller Life After Life, based on his collection of 150 coma survivor’s reports.1

Many studies and books that bear witness to life after life have sprung up since Moody’s book, none more notorious than Proof of Heaven: A Neurosurgeon’s Journey into the Afterlife, a New York Times bestseller in 2012, by neurosurgeon Eben Alexander. Increasingly, these supernatural claims have taken on a scientific veneer. Van Lommel, the cardiologist from the Netherlands, has made it clear in his many popular writings, public talks, and interviews that he believes NDEs serve as proof that consciousness exists independently of the brain, that it is “non-local.” And Sam Parnia, who researches resuscitation science and NDEs at New York University Grossman School of Medicine and was the lead researcher on a 2022 paper that proposes a framework for future study of NDEs, recently told me, “The [big] question that we’re trying to explore is, ‘What happens to consciousness when you die, does it die or continue?’ And the evidence so far is that it doesn’t die when you and I cross over into death.”

But neuroscientists who study consciousness and have weighed the decades of research into NDEs told me these claims that consciousness survives death are not supported by the research. Though they are highly personal and often transformative for those who experience them, NDEs are nonetheless explained by physiological processes, they said, which have been pieced together over the past 50 years. In the decades since Moody published Life After Life, advances in critical care medicine and resuscitation science have made it easier to revive patients whose hearts have stopped, which has made it easier to systematically identify and study people who have had an NDE. Some estimates now suggest that between 4 to 15 percent of the global population and 10 to 23 percent of cardiac arrest patients have had an NDE.2 We now have a better grasp of how they happen, what purpose they may serve and why they are so transformative for those who experience them. At the most basic level, neuroscientists say, when a person’s brain changes in profound ways—as happens when that person goes into cardiac arrest, for example—their perceptions and emotions change in profound ways, too.

“I have never felt more lucid in my life.”

“Having an out-of-body experience is not proof that the soul or the mind can leave the body and go floating about,” said Anil Seth, a professor of cognitive and computational neuroscience at the University of Sussex who studies consciousness and is the author of a recent book on the subject, Being You. Those who tout near-death experiences as something more than biological, Seth added, “are confusing the content of the experience with a claim about the nature of the universe. There’s a much more interesting explanation, which is that the location that we feel ourselves to be is something that is generated by the brain and can be changed when the brain is in a particular state.”

In 2019, a group of critical care specialists, anesthesiologists, and psychiatrists, as well as a neurologist from New York Medical College and a neurophysiologist specializing in sleep and epilepsy from Kings College in London, got together in New York to discuss the future of NDE studies. Sam Parnia, the resuscitation researcher from New York University Grossman School of Medicine, was among them. The result of that meeting was the 2022 paper in the Annals of the New York Academy of Sciences. Among other things, the authors proposed a new name for the NDE: “recalled experiences of death,” or REDs, to limit the field to the study of just those experiences that occur when someone is in critical condition, or a near-death state, such as cardiac arrest, when the brain no longer receives blood and oxygen. 

Parnia told me the new name was meant to reflect the authors’ belief that near-death experiences actually happen after someone is dead. “What we’re saying is science is showing you that death is not the end that we thought,” Parnia said. “It’s almost like a new, uncharted, unexplored territory.”

The group also identified 51 core features, or themes, of REDs. These include “separating from the body,” “realization of having died,” “a higher purpose: I wish I had known,” and “loss of fear of death.” These experiences, the paper states, are characterized by “a paradoxical lucidity and a heightened sense of consciousness, awareness, and well-structured thought processes, typically without external or visible signs of consciousness.” In a supplement to the paper, the authors allow the possibility that consciousness “is a separate entity that, while undiscovered by science today, is not produced by conventional brain cell activities.”

NDEs have been reported under many circumstances, a list of which appeared in Van Lommel’s 2001 paper: cardiac arrest in myocardial infarction, shock in postpartum loss of blood or in perioperative complications, septic or anaphylactic shock, electrocution, coma from traumatic brain damage, intracerebral hemorrhage or cerebral infarction, attempted suicide, near-drowning or asphyxia, and apnea. According to Van Lommel, they are also reported by patients with serious but not immediately life-threatening diseases, and in those with major depression. Experiences that bear many similarities to NDEs can even happen in the terminal phases of illness or after situations in which death seemed inevitable, such as mountaineering accidents.

But NDEs can also occur in circumstances that do not bear any direct relation to imminent death or even fear of death, such as meditation or intense grief, according to numerous studies, said Renaud Evrard, a clinical psychologist and assistant professor at the University of Lorraine in France, who works with patients grappling with exceptional and paranormal experiences, including NDEs. In a response paper published a few months later in the same journal, the Annals of the New York Academy of Sciences, Evrard accused Parnia and his co-authors of ignoring the actual data on NDEs.3 “They focus too much on the interpretation of testimonies and not enough on the evidence,” said Evrard. Bruce Greyson, professor of psychiatry and neurobehavioral sciences at the University of Virginia and the creator of the Greyson scale used to identify and rate NDEs, agreed, even though he is listed as an author on the 2022 paper. The evidence suggests NDEs experienced by patients whose hearts have stopped are no different from those experienced by people who simply fear death—for example, if someone is falling off of a mountain, Greyson said.

Prior belief in god or an afterlife does not, perhaps surprisingly, seem to influence one’s propensity to have an NDE, according to the research, but there is a strong association between the “depth” of the NDE a person experiences—as measured by the Greyson NDE Scale4—and the likelihood that they will experience a religious or spiritual transformation afterward, including reduced fear of death, greater empathy, and decreased interest in material possessions.5

NDEs are generally understood to begin with a feeling of detachment from the physical body—known as an out-of-body experience, or OBE—followed by deep feelings of peacefulness, entering a gateway or tunnel, seeing a bright light6 and finally feeling a “return” to the body. It is the OBE that is perhaps the most defining element of the NDE: Some 80 percent of people who report experiencing an NDE have one, according to the research of Steven Laureys, a clinical professor of neurology who leads the Coma Science Group at the University of Liège in Belgium. His lab searches for behavioral and neural correlates of consciousness in patients with severe brain damage and studies non-ordinary states of consciousness.

But a wealth of neuroscience research describes how OBE-like experiences—a loss of the sense of self and disturbed body perception or ownership—can be triggered by brain damage, epilepsy, and migraine,7 as well as by stimulation of the part of the brain where the right temporal and parietal lobes meet. This region is known as the right temporal-parietal junction (TPJ), and it is understood to play an important role in multisensory integration, our sense of embodiment, feelings of agency and self-other distinction.8 Stimulation of this junction can disrupt the brain’s ability to coherently process the positioning of the body and the sense of body ownership, which can lead to the sensation of seeing oneself from above. 

“No brain activity, no mental process.” 

OBEs often also involve awareness of specific details of the scene that feature the body in a comatose state–doctors discussing one’s chances of survival, for example, or attempting CPR. In the past, accounts from people who have recovered from being unconscious or in a minimally conscious state, and have recalled sensory details of their environments, might have seemed miraculous. But recent studies of people who are in coma, or under anesthesia, and seem unresponsive, have shown these individuals can perceive things in their environment and respond physically to commands.9 For example, while higher-level semantic processes can be impaired in people with low levels of sedation or minimally impaired consciousness, a person’s ability to process speech more generally has been found to be resilient even during deep sedation.10

Cardiac arrest may be similar. How much activity is present in the brain under these conditions is not clear. Positron emission tomography scans suggest that there is about a 60 percent reduction in global activity compared to baseline following cardiac arrest, said Laureys, but it’s not zero.11 But if a brain has flatlined, showing no activity on an EEG monitor, it would most likely be incapable of forming a memory or having any other conscious experience, said Seth, who has been studying the neuroscience of consciousness for decades. He and many others believe that most NDEs are “false” or imagined memories—that the brain constructs a memory after the fact to fill in for an inexplicable series of mental events.

“You don’t want to undermine the person’s lived experience,” Seth said. “If they experience flying through a tunnel of light, into a beautiful white open space, then that’s what they experience. But memories, things that minds do, like remember things and talk about them, depend on brain activity. No brain activity, no mental process. If somebody with no brain activity were able to experience something and remember it later, then pretty much everything we know about the brain, about science, about physics is wrong.”

While no single overarching explanation for the NDE has yet been established, neuroscientists have discovered a series of neurophysiological mechanisms that could, together, account for many aspects of the phenomenon. One hypothesis is that NDEs are produced by the release in the brain of a natural hallucinogen with neuroprotective properties. London researcher Karl Jansen, a member of the Royal College of Psychiatrists, is a leading expert on the hallucinogen ketamine, which is used to treat depression and, during surgery, as an analgesic to induce loss of consciousness and reduce pain. Jansen proposed in the 1990s that a ketamine-like substance may play a role in the emergence of NDEs among patients with life-threatening injuries or disorders of the brain or spinal cord given the parallels between NDEs and ketamine trips, and the potentially protective properties of ketamine-like substances.

The “dissociative anesthetic ketamine can reproduce all aspects of the near-death experience,” Jansen wrote. That includes a sense of ineffability, timelessness, that what is experienced is “real,” that one is actually dead, a perception of separation from the body, vivid hallucination, rapid movement through a tunnel, and emerging “into the light.”

Although many psychedelic experiences bear some similarities to NDEs, recreational ketamine trips top the list. In a massive 2019 study comparing psychedelic experiences to NDEs, Laureys’ group used natural language processing tools to assess the semantic similarity between 15,000 accounts linked to the use of 165 different psychoactive substances and 625 NDE narratives. They found that accounts of ketamine trips12 most closely resembled those of NDEs.

Ketamine is also an N-methyl D-aspartate (NMDA) receptor antagonist, and so could counter neurotoxic processes that are set into motion by NMDA receptors when blood flow and oxygen to the brain are cut off, “with a short lived, dissociative hallucinogenic state occurring as a side effect.” At least one naturally occurring substance that could play this role, called an endopsychosin, has been identified. In fact, critical conditions like hypoxia—oxygen deficiency—or temporal lobe epilepsy, have been shown to trigger NDEs or NDE-like experiences. And many studies and clinical trials have established that ketamine has neuroprotective and neuroregenerative effects in humans, even after stroke, brain injury, and epileptic seizures.13

There is likewise some experimental evidence that near-death experiences that occur at the time of a trauma might help to ward off post-traumatic stress disorder.14 Bruce Greyson, of the Greyson NDE Scale, led a study published in 2001 that showed that people who have NDEs report more intrusive memories of their close brushes with death but make fewer efforts to avoid reminders of the event, which is considered the more pathological dimension of PTSD.

“One feature that distinguishes NDEs from other forms of [traumatic] dissociation is the strong positive affect,” which might help defend against full-blown PTSD, Greyson wrote in the 2001 paper. “If so, we might speculate about the possible survival value of having NDEs when close to death.”15 (Of course, some NDEs have been documented to feature negative and even nightmarish features, though some question whether these are “true” NDEs.) 

“Ketamine can reproduce all aspects of the near-death experience.” 

Independently, serotonin, a neurotransmitter involved in mood, cognition, reward, learning, and memory, might play a role in certain features of the NDE. In a small placebo-controlled experiment with 13 individuals, Laureys’ group assessed the experiences induced by injection with a drug called DMT that stimulates serotonin production, which triggered feelings such as entering an unearthly environment, heightened senses, feelings of peace and harmony or unity with the universe. All participants scored above the cut-off score of seven on the most widely used reference scale for NDEs, the Greyson scale.16 Hypoxia itself has also been considered as a possible contributor. Hypoxia is sometimes experienced by fighter pilots during acceleration maneuvers, which have been documented to provoke tunnel visions, bright lights, OBEs, pleasant sensations, and visions of beloved ones.

To attempt to confirm this in a controlled study, one group induced temporary loss of consciousness via loss of blood pressure in 42 volunteer participants and found that 16 percent reported OBEs, 35 percent reported feelings of peace and pleasantness, 17 percent had a vision of a light, 47 percent felt they entered another world, 20 percent encountered preternatural beings, and 8 percent experienced a tunnel. Likewise, abnormally elevated levels of carbon dioxide in the blood, known as hypercarbia, can induce recollections of past memories, life reviews, visions of a light, OBEs, or mystical experiences, according to research conducted in 1950 and again in 2010.17 Yet another study showed higher prevalence of NDEs in people with REM sleep intrusions.

Other work suggests that some kind of last-gasp survival mechanism may be at work when near-death experiences occur, in which the brain marshals all of its remaining resources to try to keep itself alive. Recent EEG studies in humans and rodents seem to show highly coherent electrical activity in the brain just before death. This was first found in a small human case series in 2009 by researchers who identified transient electrical spikes in half of their sample of critically ill patients immediately before cardiac arrest. They speculated that critical hypoxia—loss of blood flow to the brain—unleashes a cascade of pathological neuronal activity. These findings were replicated on a larger sample of 35 patients in 2017. 

Similar episodes of so-called paradoxical lucidity have been identified in patients with Alzheimer’s disease just before they die, despite irreversible degeneration in the cerebral cortex and the hippocampus and corresponding memory loss. Researchers who have studied brains in the throes of electrical surges just before death have posited that they represent “a last gasp attempt by the brain to survive a lethal loss of blood flow,” which could serve as an “evolutionary survival event.”18 Why some people experience these surges and others don’t, and how they are set into motion, is unknown. 

Scientists haven’t assembled all the pieces to explain why brains in desperate throes generate feelings of peace and joy, ineffability, and the sense of being in the presence of something transcendent. “It’s always difficult for science to answer the big why questions,” Laureys said. Comas, of the Icloby Foundation, told me that by educating the public about near-death experiences, she and Melo hoped to “to eradicate the fear of death.” After all, she said, “The fear of death is the mother and father of all fears.” Who could argue with that? Scientific evidence says near-death experiences are directly linked to the workings of our brains. But evolution is a sly master. Perhaps our biology in its final hour is easing us gently into that good night.

Kristen French is a contributing editor at Nautilus.

Lead image: Lidiia / Shutterstock

References

1. Martial, C., Cassol, H., Laureys, S., & Gosseries, O. Near-death experience as a probe to explore (disconnected) consciousness. Trends in Cognitive Sciences 24, 173-183 (2020).

2. Ibid.

3. Evrard, R., Pratte, E.A., & Rabeyron, T. Sawing the branch of near-death experience research: A critical analysis of Parnia et al’s paper.” Annals of the New York Academy of Sciences 1515, 5-9 (2022).

4. Greyson, B. The near-death experience scale. The Journal of Nervous and Mental Disease 171, 369-375 (1983).

5. Greyson, B. Near-death experiences and spirituality. Zygon 41, 393-414 (2006).

6. Martial, C., Cassol, H., Laureys, S., & Gosseries, O. Near-death experience as a probe to explore (disconnected) consciousness. Trends in Cognitive Sciences 24, 173-183 (2020).

7. Blanke, O. & Arzy, S. The out-of-body experience: disturbed self-processing at the temporo-parietal junction. Neuroscientist 11, 16-24 (2005).

8. Blanke, O. & Mohr, C. Out-of-body experience, heautoscopy, and autoscopic hallucination of neurological origin: Implications for neurocognitive mechanisms of corporeal awareness and self-consciousness. Brain Research Reviews 50, 184-99 (2005); Blanke, O., Faivre, N., & Dieguez, S. Leaving body and life behind: Out-of-body and near-death experience. In Laureys, S, Gosseries, O., & Tononi, G. (Eds.) The Neurology of Consciousness (Second Edition), Academic Press, Cambridge, MA (2016).

9. Laureys, S., Perrin, F., Schnakers, C., Boly, M., & Majerus, S. Residual cognitive function in comatose, vegetative and minimally conscious states. Current Opinion in Neurology 18, 726-33 (2005).  

10. Owen, A.M., et al. Detecting awareness in the vegetative state. Science 8, 5792 (2006).

11. Ibid

12. Jansen, K.L.R. The ketamine model of the near-death experience: A central role for the N-Methyl-D-aspartate receptor. Journal of Near-Death Studies 16, 5–26 (1997).

13. Fujikawa, D.G. Neuroprotective effect of ketamine administered after status epilepticus onset. Epilepsia 36, 186-195 (1995).

14. Greyson, B. Posttraumatic stress symptoms following near-death experiences. American Journal of Orthopsychiatry 71, 368-373 (2001).

15. Ibid.

16. Timmermann, C., et al. DMT models the near-death experience. Frontiers in Psychology, 9 (2018).   

17. Klemenc-Ketis, Z., Kersnik, J., & Grmec, S. The effect of carbon dioxide on near-death experiences in out-of-hospital cardiac arrest survivors: a prospective observational study. Critical Care 14, R56 (2010).

18. Chawla, L.S., et al. Characterization of end of life electroencephalographic surges in critically ill patients. Death Studies 41, 385-392 (2017).