Life — after life: Does consciousness continue after our brain dies?

How can people brought back from death after cardiac arrest report having experienced lucid and vivid memories and recollections without a functioning brain? The study of near-death experiences is challenging the idea our consciousness fades to black when our body expires

Cornelia Li for National Post

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He could see a nurse and doctor, a bald, “chunky fella” dressed in blue hospital scrubs. He watched as they frantically worked on his body, which was remarkable, considering he was, essentially, dead.

The man had suffered a cardiac arrest. Normally there is no measurable, meaningful brain activity after the heart stops beating. Within two to 20 seconds the brain “flatlines.”

But the man would later tell researchers that he could see an unfamiliar woman beckoning from a corner up in the ceiling. “I can’t get up there,” he remembered thinking to himself, and then the next second, “I was up there, looking down at me.”

He said he saw his blood pressure being taken, and a doctor putting something down his throat. He saw a nurse pumping on his chest. He accurately and vividly described the people, sounds and events of his “resurrection.”

Cornelia Li for National Post Cornelia Li for National Post

Dr. Sam Parnia estimates the man experienced conscious awareness for three to five minutes in the absence of detectable brain activity, a time, he has said, “when no human experience should be happening whatsoever.”

The case was part of a widely reported study Parnia published in 2014 called AWARE — the awareness during resuscitation trial, the world’s largest study of what happens to the human mind and consciousness in the early period of death.

Parnia, now a critical care and resuscitation specialist at New York’s NYU Langone Medical Center, believes human consciousness may continue after our heart stops beating for some undetermined period of time.

Evidence from AWARE and other studies, he says, raises the possibility that the mind or consciousness — the psyche, the “self,” the thing that “makes me Sam” and that makes us uniquely who we are —  may not originate in the brain and may be a separate, undiscovered scientific entity, similar in nature to the electromagnetic waves that can carry sound and pictures. Modern science simply lacks the tools to show it. When we die, that entity we call consciousness or the self doesn’t necessarily become “immediately annihilated,” Parnia believes.

Parnia isn’t a religious man. He insists he isn’t after proof of the existence of an afterlife, or a supernatural hereafter. Rather, he and others are trying to find better ways to save the brain and avoid horrific “disorders of consciousness” like Terri Schiavo, the Florida woman who entered a permanent vegetative state after her brain was starved of oxygen after a cardiac arrest. But Parnia is also out to test the accuracy of seemingly fantastical claims of near-death experiencers using an objective, scientific approach.

He’s now conducting AWARE II, and would welcome Canadian collaborators.

I was up there, looking down at me

His goal is to study 1,500 people in cardiac arrest. When a “code” is called, participating researchers will be alerted and dispatched to resuscitation rooms carrying backpacks consisting of portable brain oxygen monitoring devices. The plan is to measure, second by second, the oxygen levels inside the brain. There will also be a portable EEG to measure whether the brain is functioning. As well, patients will be fitted with wireless headphones, through which random words and sounds (which need to remain secret until the study is over) will be transmitted via a tablet. Images will also be beamed upwards as people undergo CPR. Parnia doesn’t expect anyone to open their eyes. No one ever does in cardiac arrest.

“We can then look at survivors and see if they can recall any of these stimuli, and when they were able to receive information, and how that relates to their brain resuscitation quality,” Parnia announced at a recent meeting of the European Resuscitation Council.

Ultimately the goal is to try to better understand how to bring back a whole person, not a husk of one, with an intact brain and mind, by developing a kind of gold standard brain oxygen level that doctors should target during cardiac arrest and CPR in order to optimize survival without brain damage.

But a tidy flip side, Parnia says, is that “we can also study what happens to human mind and consciousness after people go beyond the threshold of death.”

In other words, how does the mind relate to the brain? “Can consciousness or the self continue to work and exist when we die?”

Throughout millennia people have tried bizarre ways to revive the dead. In the early ages, around 500 AD, people realized lifeless bodies are also cold bodies, as Parnia has described in his talks, so they covered the newly dead in warm ashes or burning animal feces, believing heat would restore life. Later came the flagellation method, the idea that the deceased could somehow be whipped into breathing again. In 16thcentury Europe, rescuers used fireplace bellows to try to push air into the lungs of corpses.

In the 1900s and early 20thcentury, and through the Second World War, we learned how to do mouth-to-mouth and chest compressions, “and everything changed,” Parnia said in an interview.

Today, advances in resuscitation medicine mean we can reverse death in people who have been without a pulse for hours. London Free Press journalist Jane Simms last year chronicled the story of Ashlyn Krell who died but was brought back to life after her car flipped on Canada’s busiest highway, trapping her in a construction hole filled with ice-cold water for 27 minutes.

More people are being successfully revived after “crashing” in a hospital, and Parnia believes even more lives could be saved, more people hauled back across that threshold of death, if more hospitals implemented more advanced techniques — chilling bodies to protect the brain, or using automated mechanical devices to deliver chest compressions beyond what any human could do.

For no matter why we die, Parnia has said — a severe infection, ridden with cancer, “hit by a lorry and haemorrhaging” — most ultimately die of cardiac arrest. Blood pressure drops, the heart isn’t able to pump enough blood to supply the body, the heart eventually stops, respiration stops, electrical activity in the brain ceases and the brain flatlines. Shine a light on the pupils and if they’re fixed and dilated, it means the brain stem has stopped functioning.

Parnia attended cardiac arrests when he was in medical school 23 years ago. Usually he didn’t know the people; they weren’t patients of his. By the time he arrived, they were essentially corpses. But towards the end of his training, he met a patient — “a sweet, lovely man” who unexpectedly went into a cardiac arrest 30 minutes after Parnia interviewed him. “It was very different and now I had personal bond with this human being and he was essentially a lifeless, emotionless body,” Parnia said.

He remembers seeing him going into a flat-line state, and people frantically trying for an hour to resuscitate the man. He remembers thinking to himself, “What happened to this person’s mind and consciousness, this sweet human being that I was talking to just a half an hour ago? Is he conscious? Is he able to see us, hear us? When did he lose it, if he did lose his consciousness?” To Parnia, it was all very blurred.

As he stood and watched, he thought: what’s been done on this, scientifically?

“Transcendental mystical or spiritual experiences close to death have been described for millennia,” Parnia wrote in 2017 in QJM: An International Journal of Medicine. Plato’s Republic told the story of the Greek warrior Er, who died in battle but was brought back and tells a tale of the afterlife. Dutch painter Hieronymus Bosch’s 15th century painting “Ascent of the Blessed” depicts a tunnel of light, with souls ascending into a heavenly place. But it was after the birth of modern intensive care medicine 40 years ago that the term “near-death experience” came to being. Philosopher and psychiatrist Raymond Moody, whose 1975 book, “Life After Life,” detailed the experiences of more than 100 once dead — people who experienced “clinical” death but were revived — coined it. The book sold more than 13 million copies.

The stories of “experiencers” share strikingly similar features: a sensation of feeling peaceful and joyous and an absence of pain; a warm, welcoming light that draws people, sometimes through a tunnel; being greeted by apparitions of deceased relatives, or a “being of light,” a panoramic review of key moments of one’s life.

The most widely used tool to quantify near-death experiences is called the Greyson NDE Scale. Published in 1983 by American psychiatrist Bruce Greyson, the scale is based on his interviews with 74 people, and scores responses to 16 questions, such as, “Did you see, or feel surrounded by, a brilliant light?” “Did you seem to enter some other unearthly world?” A score of seven or higher qualifies the experience as an NDE.

Studies have found that six to 23 per cent of cardiac-arrest survivors report lucid memories that fit with a near-death experience.

Parnia dislikes the term. He prefers “actual death experience,” and says NDE’s, for the sake of standardized scientific research, should be limited to those that correspond to an actual physiological state that approximates death.

And nothing comes as close to understanding the actual experience of death as cardiac arrest.

Dr. Sam Parnia, a critical care doctor and resuscitation specialist at NYU Langone Medical Centre in New York. NYU Langone Health

Parnia was taught in medical school that consciousness is undeniably a by-product of the brain, “that it’s probably some sort of epiphenomenon that arises from synaptic activity,” meaning the communication between neurons. Numerous studies show a correlation between the activity of the mind and changes in the brain. Slide someone inside a functional MRI and ask him or her to think about something happy or sad. Synaptic changes in oxygen or glucose levels in particular parts of the brain light up. “The problem with all those studies are that none of them are causative — none of them show you how brain cells could possibly generate a thought, which is the fundamental problem of consciousness,” Parnia says.

“If you look down a microscope at a brain cell, and I said to you, this brain cell is now thinking, you’d say that’s crazy, it’s a brain cell.” Brain cells produce proteins that generate changes in sodium, which generates electricity. “That’s not a thought,” Parnia says.

“And if I said, well, somehow, if I connect a hundred or a thousand or a million of these cells together, it just leads to this magical phenomenon of thought. There’s no mechanism to account for why that should occur. Why would my brain cells, millions of them connected together, suddenly feel guilty, or have a sentiment of guilt, like if I were to throw a brick in my neighbour’s window, or be rude to somebody or do something immoral?”

The moment the heart stops, the brain shuts down from a functional perspective, he said. “Yet, paradoxically, what we started to see is that millions of people have now been resuscitated, and many of them have reported these very lucid, well-structured thought processes.” They’re able to form memories, describe conversations and what people were wearing. “Except that their brain has shut down and they’ve gone through death. Which is completely a paradox, it should not happen. If your mind is simply a by-product of your brain, if your brain has shut down, there should be no consciousness.”


The phenomenon has been described worldwide, from Japan, India, the Middle East and the Americas. They’re remarkably consistent across cultures and religions, and have been reported by children as young as preschoolers. Parnia once interviewed a three-year-old boy who survived a cardiac arrest after an epileptic seizure. “When I died, I saw a bright lamp,” the boy told Parnia during a play session. “Grandma came to meet me and said I was going to be okay.” Other children have described the “being of light” not as God, or Jesus, but Santa Claus. Toddlers aren’t exposed to religious doctrine, says Dr. Elaine Drysdale, a clinical professor in the department of psychiatry at the University of British Columbia. Yet they report near-death experiences similar to older children and adults.

Parnia’s detractors have accused him of “dog whistling to theists.” The notion of a soul or mind existing separate from the body is scientific flapdoodle, they say. Renowned Western University neuroscientist Adrian Owen, who has devoted much of his career searching for signs of consciousness in “vegetative” patients, says the brain is the organ that produces consciousness, full stop. “If you take that organ away or kill that organ or that organ dies, you cannot be conscious.” While there is no identified conscious centre of the brain — nothing you can point to and say, ‘there, that’s where it all happens” — Owen was part of an international team that recently identified two particularly distinct patterns of complex brain activity that can differentiate a conscious brain from an unconscious one.

He doesn’t believe patients who report near-death experiences get to a state where there’s no detectable brain response whatsoever. If that were true they would be classified as brain dead, “and I know of no case in the literature of a brain dead patient coming back.” Owen’s not saying they’re not almost dead. But the brain has an amazing vasculature. Unless a person dies of massive trauma that knocks out all brain function immediately, like going through the windshield of a car, parts of the brain will continue to get oxygen for some time after the heart stops, Owen says.

Memories or sensations of a seemingly disembodied consciousness could also be happening before the brain shuts down, or after heart and brain function start coming back online. NDE denier and Australian anesthesiologist G. M. Woerlee has argued compressions during CPR itself can push blood around the body and through the brain in sufficient enough amounts to sustain some form of consciousness, and that these people “are most definitely not ‘flatlined.’ ”

In fact, McGill University doctors reported last year the case of a 38-year-old man who appeared to regain consciousness several times during CPR. The man was defibrillated six times. Throughout the ordeal he made “purposeful movements to push CPR providers away” and verbalized with each jolt of the defibrillator, Dr. Roger Gray reported in the journal Canadian Family Physician. When signs of consciousness were recognized, CPR was immediately halted, and his pulse checked. There was no palpable pulse. Restraints were applied, CPR resumed and his heart resumed beating again 17 minutes after he initially went into cardiac arrest.

When interviewed three months later, he recalled experiencing discomfort in his chest and neck, but no pain. Although he made a complete recovery, the situation was distressing for his resuscitators. None “had ever experienced a patient regaining consciousness with CPR, nor were they aware that it was possible.”

Jimo Borjigin is an associate professor at the University of Michigan Medical School. In experiments in rats, Borjigin and her colleagues discovered that the rodents experienced a huge surge in the secretion of brain chemicals within the first 30 seconds after the heart stops. Their dying brains seemed to become highly aroused. “Serotonin in particular was very high,” she says. “We know that the serotonin is associated with hallucinations and other mental functions.”

Yes, the overall level of electrical activity of the brain was lower, Borjigin says. “But the part that is at least partly responsible for conscious information processing is actually increased tremendously in the dying brain,” she says— for 30 seconds at least.

More astonishing, researchers at Western University reported two years ago the case of a patient who was taken off life support who continued to show bursts of brain wave activity for up to 10 minutes after the final heartbeat.

The authors don’t know how to explain the post-mortem delta wave bursts. It was also a sample size of one. Parnia, for his part, doubts the brain activity recorded in the otherwise dead rats would be adequate to produce the kind of lucid and vivid memories reported by humans who claim to have gone through a near-death experience.

He also has trouble with the hallucination theory. When people have a lack of oxygen to the brain — something Parnia sees daily in the intensive care unit —they become completely delusional and disoriented. With delusions, thinking becomes fragment, a muddled mess. “They don’t have well-structured thought processes,” he says. They thrash about and, if the oxygen becomes too low, they go into a coma. NDE-ers, by contrast, report vivid experiences.

In addition, “people are coming back and describing real events that have occurred and that doctors and nurses have verified, validated.” So, by definition, they can’t be hallucinations, because they’re describing real events, he argues.

This isn’t the “locked-in” syndrome, where people are conscious and can think and reason but unable to speak or move. Or people in a “vegetative” state because of a severe brain injury. People who report near-death experiences describe their consciousness separating out, withdrawing from their bodies. Says Parnia: “They’re watching it, they can see it happening to them, but they’re not in pain and they’re wondering why everyone is worrying about them. ‘I don’t understand why they think I’m dead because I don’t feel dead, although I don’t know what I’m doing up here in the corner of the room.’”

The original AWARE trial involved 2,060 cardiac arrests across 15 hospitals in the U.S., the U.K. and Austria. Of those, 330 people survived. Nine who were able to undergo detailed interviews had experiences compatible with a near-death experience, Parnia and his co-authors reported in the journal, Resuscitation. Two reported an out-of-body experience; including the man who reported “seeing” and “hearing” things as he hovered near the ceiling over his lifeless body.

But there’s a hitch: To test the veracity of out-of-body experiences, or OBEs, researchers had stacked shelves in rooms where people were most likely to go into cardiac arrest, like coronary care units, the ICU and emergency wards. Atop each stack of shelves, visible only from the ceiling looking down, were hidden targets  – pictures of a baby, a pink dog, a newspaper headline of Princess Diana’s death. The researchers were after visually “veridical” OBEs, in which the experiencer reports verifiable information that could never have been obtained by any earthly means. Skeptics have argued that it’s entirely possible people see or hear things while the brain’s sensory pathways are shutting down. But what if they could get verifiable proof of “remote viewing?”

However, most of the cardiac arrests took place in areas without the shelves. None of the nine who reported NDEs — and neither of the two who reported out-of-body experiences — reported seeing the hidden images.

Even fleeting bursts of electrical activity deep in the brain’s temporal lobe, even a few seconds worth, can evoke experiences of the paranormal and mystical. Last August, a team from Imperial College London reported that the psychedelic drug DMT mimics near-death experiences in the brain. Thirteen volunteers given intravenous DMT completed the Greyson scale — that standardized questionnaire that tries to quantify near-death experiences. They all scored above the threshold for an NDE. Dr. Robin Carhart-Harris, the study’s supervisor, noted when the paper was released: “These findings are important as they remind us that NDEs occur because of significant changes in the way the brain is working, not because of something beyond the brain.”

Parnia allows that it’s entirely possible people who report conscious experiences during cardiac arrest also had higher blood and oxygen flow to their brains. But that doesn’t make the experiences illusory or unreal, he says. Studies have found that NDE memories are richer in detail — they seem more real — than memories of real life events. To Drysdale, of the U of BC, that suggests “that as the brain is shutting down, our consciousness actually increases.”

But when is the brain, really, dead?

“The precise point beyond which the brain is no longer ‘living,’ a threshold which remains unidentified, is perhaps less definite than has been historically assumed,” Laurentian University researchers wrote in PLOS One in 2016. Death is a process, Parnia says, not an absolute, black-and-white moment. “It’s actually only after a person has died that the cells start to undergo their own process of death, and that can take hours.”

Even when the brain flat lines — no sign of brain waves on a standard EEG — brain cells don’t die immediately, Parnia says. It may take hours before they become permanently damaged.

In 2012, researchers at the Pasteur Institute of Paris discovered stem cells could remain alive in human corpses for at least 17 days after death (the cadavers were stored in a mortuary at four degrees Celsius to keep the bodies from decomposing.) A Baltimore team has been able to generate living stem cells from the scalps and brain linings of people who had been dead for up to 21 hours. The Laurentian team was able to elicit living-like, electrophysiological responses in post-mortem human brains when they exposed the dead brain tissue to chemical and electrical probes. “When the brain is dead and the tissue has lost its structural integrity, the individual is assumed to no longer be represented within what remains of the organ,” the researchers wrote in PLoS One. “Together, these results suggest that portions of the post-mortem human brain may retain latent capacities to respond with potential life-like and virtual properties.”

That’s certainly what the people putting up US$10,000 to have their brains cryogenically frozen or “vitrified” are banking on. One Silicon Valley start up claims to be developing technology that can preserve not just the physical brain, but also the memories within it, with the goal to one day upload those frozen memories into a server so people can live a new life as a computer simulation, perhaps a robot.

But absent vitrification, and certainly without any life support, the brain eventually degrades. Death after cardiac arrest is reversible — up to a point. And there’s still no verifiable evidence that anything like consciousness leaves the dying body.

“For materialists, we are each our brain and we die with it,” Gregory M. Nixon wrote in the Journal of Consciousness Exploration and Research. Francis Crick, co-discoverer of DNA said consciousness was an epiphenomenon, a by-product of synaptic activity in the brain. Still, there were Nobel winners in both camps: Sir John Eccles, who won in 1963 for his work on the synapse, dismissed the mind-brain theory, arguing, “The human mystery is incredibly demeaned” by such scientific reductionism. The field remains similarly divided today.

Parnia says he’s keeping an open mind. He cringes at recent headlines claiming, “When you die you actually KNOW you’re dead because your brain still works for a while.” The whole idea is seriously unsettling, and, Parnia noted in a recent interview with Newsweek, the idea “petrifies people.” For some, it also raises a creepy corollary: could we watch our organs being retrieved while floating, disembodied, near the ceiling?

If nothing else, Parnia says that people who come back from clinical death — accepting that they were technically dead —who report having seen brilliant lights or entering a supernatural realm often become wholly transformed by the experience. They become more altruistic, less self-centred, more engaged with helping others. Less afraid of death. “They view the world in a different way,” Parnia says.

Still, near-death experiences aren’t all cosmic light and luminous, loving beings. Some, as Bruce Greyson and Nancy Evans Bush wrote in the journal Psychiatry in 1992, are “frankly hellish.” Some people have described being sucked into voids, or seeing grotesque beings wailing and moaning. “There are people who tried to commit suicide whose experiences have been very, very unpleasant and problematic for them,” Parnia says.

He was young and naïve when he first embarked on the mind-body question 20 years ago. “I thought to myself, we can probably figure this out in, like, a year, year-and-a-half of research,” he says.

“We’re all conscious, thinking beings. Everything we do starts with consciousness. Yet we don’t know fundamentally where it comes from.”

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