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Lifting the Veil on Near-Death Experiences

What the neuroscience of near-death experiences tells us about human consciousness

Illustration of a person on a hospital bed having an out of body experience within a hospital setting

Galen Dara Smith

For decades François d’Adesky, a retired diplomat and civil servant who now lives in Brussels, spoke to no one about his near-death experience (NDE). It happened at the age of 13, when he was hospitalized for acute appendicitis. D’Adesky vividly recalls seeing his body on the operating table and then passing through a tunnel, where he met strange beings who radiated luminosity and goodness. “Your time has not come,” an older being, whom d’Adesky intuited was God, told him. “You have not undertaken your Earth mission.”

Then d’Adesky perceived traveling “at breakneck speed through time and space, back to the beginning of the creation of the world,” he says. He eventually arrived at a gardenlike paradise where spiritual beings—one of whom was his deceased grandmother, another a childhood friend who had died at the age of five—communicated telepathically with him. D’Adesky’s grandmother took him by the hand and led him back into the clinic, where he woke up in his body in excruciating pain.

D’Adesky spent his adult life striving to discover what his special mission was. Eventually he came to see it as the role he played in “making the world a better place,” he says. That included helping, as an official with the United Nations, to get a key resolution passed at the 2011 U.N. Climate Change Conference. It wasn’t until a few years later, though, when NDEs were entering the public discourse more often, that he started sharing the story of his pivotal experience beyond his immediate family. “I had been afraid for my reputation,” he says.

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Near-death experiences have been reported across time and cultures. An astounding 5 to 10 percent of the general population is estimated to have memories of an NDE, including somewhere between 10 and 23 percent of cardiac arrest survivors. A growing number of scholars now accept NDEs as a unique mental state that can offer novel insights into the nature of consciousness. “Now, clearly, we don’t question anymore the reality of near-death experiences,” says Charlotte Martial, a neuroscientist at the University of Liège in Belgium. “People who report an experience really did experience something.”

Those who undergo an NDE also return with “this noetic quality from the experience, which very often changes their life,” adds neuroscientist Christof Koch of the Allen Institute in Seattle, who writes about NDEs and other states of consciousness in his 2024 book, Then I Am Myself the World. “They know what they’ve seen.”

A handful of researchers, mostly emergency room doctors, began collecting qualitative data about NDEs after the 1975 publication of psychiatrist and physician Raymond A. Moody’s book Life after Life, which detailed patients’ accounts of near-death experiences. Since then, only a few research teams have attempted to empirically investigate the neurobiology of NDEs. But their findings are already challenging long-held beliefs about the dying brain, including that consciousness ceases almost immediately after the heart stops beating. This discovery has important implications for current resuscitation practices, which are based on outdated beliefs about what happens to the brain during cardiac arrest, says neuroscientist Jimo Borjigin of the University of Michigan Medical School. “If we understand the mechanisms of death, then this could lead to new ways of saving lives.”

Like psychedelic drugs and other means of altering consciousness, NDEs could also serve as probes for revealing fundamental truths about the mind and brain. Such states are perturbations to the system of consciousness, “and when you perturb a system, you understand better how it works,” says Christopher Timmermann, a postdoctoral fellow at the Center for Psychedelic Research at Imperial College London. “If we want to understand the nature of experience, we have to take into account what’s happening at the margins of nonordinary states.”

Moreover, there are important existential implications, although exactly what those might be continues to be debated in the scientific literature and at conferences, including at a 2023 meeting held by the New York Academy of Sciences. It explored consciousness through the lens of death, psychedelics and mysticism. “These transcendent experiences are found in the major world religions and traditions,” says Anthony Bossis, a clinical assistant professor of psychiatry at the New York University Grossman School of Medicine, who helped to organize the conference. “Might they have some greater purpose for helping humanity cultivate understanding and awareness of consciousness?” he asks. The weightiness of such questions makes careful study of NDEs and their rigorous interpretation all the more critical, Martial says: “It’s important to disentangle empirical findings versus belief.”

On an overcast February afternoon, Martial was meeting with the 20 members of her neuroscience laboratory when her phone began to ring. She had asked to be alerted if someone arrived at the Liège university hospital on the verge of death.

Martial bolted toward the elevator, and within about two minutes she made it into the hospital lobby, its crisscrossing escalators and geometric motifs reminiscent of an M. C. Escher drawing. In the resuscitation room, Aurore Ancion, an emergency physician and doctoral candidate in medical sciences, was already waiting. Laid out on one of the room’s two beds was a bearded man in his mid-70s, his hospital gown open to expose his belly and chest.

Despite being in the middle of an episode of atrial fibrillation, the man was alert and cracking jokes. He giggled nervously as Ancion, working around two emergency doctors, placed a cap over his head for an electroencephalogram (or EEG, to measure electrical signals in the brain) and adhered two oxygen readers to his forehead. Martial, standing in the back, peered through tortoiseshell glasses at a laptop, where two spiky lines in red and blue began scrolling across the screen—precise measurements, to the trained eye, of the patient’s brain activity.

The doctors eventually had to anesthetize the man and shock his heart back into a normal rhythm. Martial and her colleagues hope the data from his and other patients’ visits to the resuscitation room and from follow-up interviews will provide the most detailed picture to date of what transpires in the human brain during close encounters with death.

Many people who had an NDE describe one or more of a specific set of characteristics. They may recall separating from their body and viewing it in real time from above. They may pass through tunnels and see light, encounter deceased relatives or compassionate entities, and have a sense of vastness and deep insight. People may undergo a life review and morally evaluate the choices they have made, including by experiencing the joy or pain their actions caused others. “What’s intriguing is that when people die, they don’t evaluate themselves based on their own standards of morals,” says Sam Parnia, director of critical care and resuscitation research at the N.Y.U. Grossman School of Medicine. “They evaluate themselves based on a universal standard.”

Although most people describe their NDE in glowing terms, a minority recount visits to hell-like regions, encounters with demonic beings or terrifying voids. In a 2019 study, Martial and her colleagues found that among 123 people who reported an NDE, 14 percent classified it as negative—a proportion Martial says she’s “sure” is an underestimate because of how disturbing these memories can be.

Somewhat surprisingly, religious people don’t seem to be more inclined toward NDEs. There is, however, preliminary evidence of another group being more likely to have NDEs: those who are prone to REM sleep intrusion, a condition that occurs when rapid eye movement (REM) sleep intrudes into wakefulness and blends elements of dreaming and waking. During the seconds or minutes it lasts for, people may have an out-of-body experience, sense that someone or something is in the room with them, or want to move but find that they can’t. In 2019 Daniel Kondziella, a neurologist at the Copenhagen University Hospital network’s Rigshospitalet, and his colleagues recruited a sample of 1,034 adults from the general population in 35 countries. Ten percent of the study participants had experienced an NDE, and of those, 47 percent also reported REM sleep intrusion—a statistically significant association. Among the people who had not had NDEs, just 14 percent reported REM sleep intrusion.

Still, little is known about the neurobiology of NDEs. Open questions include whether they are driven by a single, core mechanism or are a more variable response to “understanding somehow that death is near,” as Timmermann says. A few researchers, including Martial, are peering into the brains of people who are approaching or undergoing death, in the hope of understanding what is going on.

In 2023 Borjigin and her colleagues published what they suspect could be a signature of NDEs in the dying brain. The researchers analyzed EEG data from four comatose patients before and after their ventilators were removed. As their brains became deprived of oxygen, two of the dying patients exhibited a paradoxical surge of gamma activity, a type of high-frequency brain wave linked to the formation of memory and the integration of information.

Borjigin had seen the same upwelling of activity in previous studies of the brains of healthy rats during induced cardiac arrest. In the rodents, the surge occurred across the entire brain. In humans, though, it was confined primarily to the junction of the brain’s temporal, parietal and occipital lobes, a region involved in multiple features of consciousness, including visual, auditory and motion processing. Past research has also associated the region with out-of-body sensations, as well as with altruism and empathy. Although these are all regular components of NDEs, Borjigin says, it’s impossible to know whether the two patients actually experienced an NDE because they did not live to tell about it. But “I could almost guess what they might have experienced,” she says.

A 2023 study led by Parnia and detailed in his forthcoming 2024 book, Lucid Dying, provides further evidence of brain activity after patients’ hearts have stopped. Parnia and his colleagues worked with 25 hospitals in the U.S., the U.K. and Bulgaria to review EEG and brain-oxygen data from 567 people who experienced an in-hospital cardiac arrest. Medical staff managed to collect interpretable EEG data from 53 of these patients. Most showed an electrical flatline during the crisis, but in around 40 percent of those cases, neurological activity consistent with that of conscious brains transiently reemerged—in some instances up to an hour into CPR.

A different subset of 53 patients from the study survived. Doctors collected EEG and brain-oxygen levels for too few of these people to draw a correlation between any potential memory they had of the event and their brain activity. The authors were able to interview 28 of the survivors, and six had a “recalled experience of death,” as Parnia refers to NDEs.

Parnia and his colleagues also sought to test conscious and unconscious awareness, including reports of out-of-body experiences, by projecting a series of 10 random images on a tablet placed near patients’ heads and by playing a repeated recording of the names of three fruits—apple, pear, banana—to them through headphones every minute for five minutes while they were unconscious. None of the survivors could remember the images that had been projected. One person who had a recalled experience of death correctly named the fruits in order, although this could have been by chance, Parnia says.

3D qualitative chart plots a range of states, including awake, coma, near-death experience, near-death-like experience, and several sleep and anesthesia-related states. Axes are awareness, wakefulness and connectedness.

Violet Isabelle Frances for Bryan Christie Design; Source: “Near-Death Experience as a Probe to Explore (Disconnected) Consciousness,” by Charlotte Martial et al., in Trends in Cognitive Sciences, Vol. 24; March 2020 (reference)

According to Parnia, this study presents “a coherent, mechanistic explanation” for how and why people have recalled experiences of death. When someone starts dying, Parnia says, the brain becomes dysfunctional. Some actions are immediately lost, such as brain stem reflexes, but others that are normally suppressed to optimize performance for ordinary life suddenly become disinhibited because the brain’s natural braking systems are no longer working. As a result, “your entire consciousness comes to the fore,” Parnia says. The purpose of this change, he suggests, is to prepare the person “for a new reality”—the transition from life to death, a condition in which, Parnia believes, consciousness endures.

Other scientists flatly disagree. “When you have an NDE, you must have a functioning brain to store the memory, and you have to survive with an intact brain so you can retrieve that memory and tell about it,” Kondziella says. “You can’t do that without a functioning brain, so all those arguments that NDEs prove that there’s consciousness outside the brain are simply nonsense.”

Kondziella, Martial, and others instead theorize that NDEs might be part of a last-ditch survival tactic. Species across the animal kingdom “play dead”—a behavior technically called thanatosis—when they perceive a mortal threat, typically from an attacking predator. If fight-or-flight fails, the instinct to feign death kicks in as an attempt to forestall the danger. The animal becomes immobilized and unresponsive to external stimuli—but with continued awareness so that, given a chance, it can escape. “Personally, I believe the evolutionary aspect really is the key to understanding what NDEs are and how they came about,” Kondziella says. “There is a perfectly valid biological explanation.”

Martial and others have also criticized the methodological rigor of Parnia’s study. One concern, Martial says, is that the team based its findings on visual readings of patients’ EEGs rather than on “a proper statistical analysis.” Parnia says he and his colleagues applied the standard method for reading EEGs that “every physician in the world” uses in clinical practice. Those who are criticizing the study, he adds, are “just ignoring it because [they] don’t like it.”

In their latest study, Martial and her colleagues plan to use the most rigorous approach to date to collect both subjective and objective data from around 100 patients, including EEG and brain-oxygen readings, plus information from several rounds of interviews and surveys with survivors in the group. The University of Liège team is also trying to more thoroughly evaluate claims about out-of-body experiences. Around 79 percent of people who have an NDE report leaving their body, and some wake up knowing facts about their environment that they seemingly should not know. “I’m not saying it’s not true, but here we want to objectively test it,” Martial says.

To this end, she and her colleagues have decorated the hospital resuscitation room with unexpected objects and images, some of which are hidden in places that could be viewed only from the vantage point of someone near the ceiling. While a patient is in the resuscitation room, including while they are conscious, the team plays an audio clip of various words and animal sounds once every minute. They will test for recollections of any images or sounds in follow-ups with surviving participants, and they will also use video recordings to compare people’s memories with reality.

An easier approach to studying NDEs is via safe proxies such as hypnosis, induced fainting and psychedelic drugs. None of these methods produce true NDEs, but the states they trigger may have some overlap with the dying brain. In 2018 Timmermann, Martial and their colleagues published a study comparing NDEs with the effects of N,N-dimethyltryptamine (DMT), a mind-altering component of ayahuasca, a South American plant-derived psychedelic brew. Trace amounts of DMT also occur endogenously in humans. “There’s speculation that that’s somehow underlying NDEs, but the data are very elementary,” Timmermann says.

In the study, 13 volunteers received intravenous DMT in a lab setting and rated their experience on a scale commonly used to measure NDEs, developed by psychiatrist Bruce Greyson in 1983. The researchers compared the DMT group’s scores and subjective accounts with other people’s taken from an NDE database that Martial and her colleagues have been compiling since 2016. (The database includes around 2,000 accounts, accepted from anyone who contacts the Liège team claiming to have had an NDE and then fills out a lengthy questionnaire.)

They found “striking overlap” between the DMT and NDE groups, Martial says, with people in both describing a sense of entering into an unearthly realm, separating from their body, encountering mystical beings and seeing a bright light. People in both groups also reported feelings of peace, unity and joy. There was just one significant difference: those in the NDE group more frequently experienced reaching a border demarcating a point of no return.

Roland Griffiths, a psychiatrist at Johns Hopkins University who pioneered studies of psilocybin and who died last October, reported similar findings with his colleagues in 2022. The authors compared 3,192 people who had undergone an NDE, a psychedelic drug trip or a non-drug-induced mystical experience. The team found “remarkably similar” long-term outcomes across subjects in all three groups, including a reduced fear of death and lasting positive effects of insights they had gained.

In another study currently undergoing peerreview, Martial, Timmermann and their colleagues interviewed 31 people who had experienced an NDE and had also tried a psychedelic drug—LSD, psilocybin, ayahuasca, DMT or mescaline—to see what they had to say about the similarities and differences between the events. Participants reported stronger sensory effects during their NDE, including the sensation of being disembodied, but stronger visual imagery during their drug trip. They reported feelings of spirituality, connectedness and deeper meaning across both.

In comparisons of these mystical experiences, “the common ground that’s striking to me is in things like a profound, deep sense of love—that all is love and that consciousness is love,” says Bossis, who studies the effects of psilocybin in people with terminal cancer, focusing on relieving end-of-life distress, enhancing spirituality, and providing a greater sense of meaning and fulfillment in life. “There’s also a sense of transcending time as we know it and a greater acceptance of the mystery of life and death.”

To Guy Vander Linden, a retired government administrator in Brussels, his NDE is still a “gift.” It happened in 1990 after a serious bike accident. He was enveloped by a force of overwhelming love and a deep sense of “spirituality not connected to religion,” he says. He also felt an expansiveness in which “I was everything and nothing.”

Vander Linden left the hospital a different person. His fear of death was extinguished, he says, because he now knew that “to die is something fantastic.” He no longer saw value in material things and got rid of his car and two extra houses. He also felt compelled to share his NDE with others through books and conferences. These changes affected his relationships, including with his wife, whom he has since divorced. “She said I’m crazy,” Vander Linden recalls. “To come back with an experience that others haven’t had—it creates conflict.” Years later he is still able to tap into the love he felt when he was bathed in the clear light of what he’s come to conceive of as universal consciousness.

Regardless of how people interpret NDEs, studying them may expand the boundaries of resuscitation, provide a better understanding of mind and brain, and shine a flicker of light on some of the deepest mysteries of existence.