What happens when we die? Big Brains podcast with Sam Parnia

Show Notes

For centuries, death has been seen as a final, inescapable line—a moment when the heart stops and the brain ceases to function. But revolutionary research asks: What if everything we thought we knew about death was wrong?

Sam Parnia, an associate professor of medicine at NYU Langone, is the author of Lucid Dying: The New Science Revolutionizing How We Understand Life and Death. His groundbreaking work explores how science is pushing the boundaries of life and death, uncovering the potential to resuscitate animals—and maybe one day humans—after they've been declared dead. From recalling experiences of consciousness after death (what some call “near-death experiences”) to using AI and advanced techniques to study the brain in its final moments, he explores the profound implications for medicine, ethics and our understanding of what it means to be alive.

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(Episode published December 5, 2024)

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Transcript:

Paul Rand: It’s an experience every one of us is guaranteed to go through in our lives. It’s inescapable, and so we often don’t question it, we just accept it without wondering what exactly is death and how do we know when it’s happened.

Sam Parnia: In general, everyone who listens to this podcast, including I would say 99.9% of physicians, scientists, and so on, we’re all conditioned by the way society views life and death in a very clear binary separable ways.

Paul Rand: That’s Sam Parnia, associate professor of Medicine at NYU Langone, where he is also the director of research into cardiopulmonary resuscitation and the author of a new book, Lucid Dying: The New Science Revolutionizing How We Understand Life and Death.

Sam Parnia: And what I’m trying to illustrate to you is that actually the idea that we have that there’s a clear line that delineates life from death is a social convention. It is not grounded in the realities that exist in the human body. Mammalian body, I should say.

Paul Rand: The research by Parnia and others into resuscitation is completely revolutionizing what we mean when we talk about death.

Sam Parnia: I’m an intensive care doctor and my area of expertise is looking at the brain, how to restart the heart after people die, and how to preserve the brain so that they can come back to life and enjoy a meaningful life, work, society, and so on.

Paul Rand: Is it possible that we’re accepting people are dead too early, that our view of when life ends is actually keeping people from possibly being brought back? And when we say brought back, what do we mean? What happens to consciousness and the space between life and death?

What happens when you die?

Sam Parnia: There is this perception that if you ask the question of what happens to consciousness after death, you’re talking about something philosophy or theology and so on. And people have created these artificial borders where they say, “Well, this is not science.” Of course, it’s science. I’m a physician, I deal with life and death all the time. The work I’m trying to do is trying to restore life in people after death. So in order for us to study this and make sure that we don’t do any harm but also recognize that what happens to the individuals, we have to bring in the study of consciousness.

Paul Rand: Parnia has not only been pushing the boundaries on our understanding of death, as director of the Human Consciousness Project at the University of Southampton, he also conducted the largest study of people who recalled experiences of death and used AI technology to reveal some mind-blowing findings.

Sam Parnia: Like it or not, science has moved into the post-mortem period. Science has moved into what people used to think was philosophy, what happens after death.

Paul Rand: Welcome to Big Brains where we translate the biggest ideas and complex discoveries into digestible brain food. Big Brains, little bites, from the University of Chicago Podcast Network. I’m your host, Paul Rand. On today’s episode, Using Science to Understand Death. Big Brains is supported by UChicago’s online Master of Liberal Arts program, which empowers working professionals to think deeply, communicate clearly, and act purposely to advance their careers. Choose from optional concentrations and ethics and leadership, literary studies, and tech and society. More at mla.uchicago.edu. So I am going to start with a really hopefully easy question just to get us going. What is death and how do we know when it has occurred?

Sam Parnia: I mean one of the biggest things that we face every day, it seems very simple, what is life, what is death. And the challenge that we have right now because of advances in science and medicine is that actually, it’s not as clear as people would think or would imagine. Science has shown that actually even after a person dies, that actually the cells inside of the body do not suddenly decompose or degrade and that there is a fairly long period of time in which even the brain can be preserved even after people have died. The reality is once you go into the person’s body and look at it more biologically, there is no clear line. What we do know is that there is a clear line when you extend hours of time. It’s a little bit like saying if you and I were flying across the Atlantic, we’re going from let’s say New York to London. And we know that in New York it’s daytime and in London it’s the evening time, it’s darkness.

But when you fly, you start in light, and then somewhere along the line, it starts to get progressively less light, less light, more gray. And then eventually at some point, it is total darkness. But there isn’t a line. Where would you draw that line? And so we think in society, we just think of the light and the darkness, and we think these things happen immediately after each other. And the point we’re trying to make is the human body, the mammalian body, the reality of science is that there isn’t. There is this transition from light to darkness, but it happens over many, many hours of time.

That has clear medical ramifications for society because it means if you don’t assume that you’ve reached darkness, if you recognize that it’s still shades of gray, you can try to pull people back into the light when they’ve died. If you label people as the end, you say, oh, that’s the end, then you won’t try because you think it doesn’t exist. Almost all doctors, including even most neuroscientists and scientists who are trained, they’re taught that after about 5, maybe 10 minutes of oxygen deprivation to the brain, the brain is irreversibly damaged and dies. And that is actually not true. That has been shown now for more than two decades to be not quite the whole truth of the story.

Paul Rand: There’s been some research that you’ve done and others have done that really brings this all to life. And I’m thinking specifically of the work that was done by Dr. Sestan. It has to do with pigs. And I wonder if you can explain that study and give some background on it.

Sam Parnia: Dr. Nenad Sestan who’s a neuroscientist at Yale was also experimenting with the brain in the early 2000s onward and was interested to understand all the connections that exist in the brain. He wanted to find brain tissue that he could use, and he decided to work with a slaughterhouse for ethical reasons because he didn’t want to kill animals. And he asked if he could be given the brains that were being discarded after the animals had been killed and their meat was used for obviously making sausage and so on. But importantly, they collected these four hours after the animals were killed. And what they were able to then do, and they published this in 2019 in Nature, was they took 32 dead pig brains and they connected them to a cocktail of drugs that have brain-preserving properties. And they were given these drugs over 6 to 10 hours. So now you’re looking at pig brains from pigs that had died 10 to 14 hours earlier. And they were able to show that in all of these cases, able to restore brain function in those pig brains.

Paul Rand: That’s just amazing.

Tape: Brains of 32 dead pigs were connected to an artificial blood supply pumping it around the organ, which in turn restored some activity in the brain cells. The surprise findings have raised hopes for medical advances and raised questions about the definition of death.

Sam Parnia: Which shows you that the brain had not died and that if you knew what to do, you could restore life to it.

Paul Rand: So let’s pull that apart a little bit. Is there a difference between functioning and consciousness in this case? And if so, how do we understand the two?

What happens to consciousness after death?

Sam Parnia: Well, consciousness is one of the most intriguing questions. You and I are both conscious-thinking human beings. And in fact, all of us, everyone who’s listening, everything that we do is actually reflected, firstly, from our own consciousness. We make decisions. I made a decision to talk today. You made a decision to invite me. But of course, when you come to the hospital, we have ways of diminishing your consciousness from the outside perspective and diminishing your memory formations and so on. In other words, when we go for surgery, doctors will give us sedation or anesthetic agents that will put us into a deep sleep or into a coma of some sorts, and so we lose awareness of our environment.

And in the study that was carried out with the pigs, one of the drugs that was given, if not more, that was designed to preserve the brain, also had the effect that it would stop the brain signaling, the electrical signaling that goes across the whole brain, the cortex of the brain that we normally see when people are conscious, aware, and listening. If they did an EEG, a brain monitor of you and I, they would see those signals. But simply those animals were given drugs that prevented those signals from being seen. And so, in a sense, think of it as if the animals were given an anesthetic while the brain function had been restored.

Paul Rand: And so what if they weren’t given that drug?

Sam Parnia: If they weren’t given that drug, there was a huge concern that those animals may well become fully conscious again and aware of their environment. And that’s why in part on ethical grounds, they were given those drugs.

Paul Rand: Wow. All right. Well, that’s huge on many different levels. And of course, everybody listening is now saying, “Well, wait a minute, could this apply to humans?”

Sam Parnia: And I think the answer is yes. You have to appreciate. I mean, this was the first time that this was done. And this is a huge... really a leap for humankind is that you can take a person who has been dead for many hours and if you know what to do, what medications to give them, you can in principle restore life and restore an activity to the brain, and importantly, without any brain damage. None of those pig brains had any signs of damage. And that was a key thing that came out of that. So the field of resuscitation, think of how huge this is. Think of all the people that you read in the news who are declared dead on the scene because of an accident, because of an unfortunate sudden heart attack. Ambulance crews arrive, they try to resuscitate, they declare the person dead on the scene. If they knew that this kind of technology was available and we could implement it, then many of those people who are otherwise healthy who died, youngish people, healthy people could have their lives restored to them.

Paul Rand: This may be completely speculative, but in the case of the pigs, and if they were brought back to consciousness, would it be the same animal that it was prior to death? And would it be the same being? Would it be the same being that it was prior to death?

Sam Parnia: Well, you highlighted one of the key elements. You said to me, what about consciousness? Now, unfortunately, the way that people look at this today is still very much philosophical. And it’s not going to be a surprise if I tell you that talking about what happens with death and what happens after death is a highly controversial area because everyone has an opinion about it. But those opinions are grounded in their own personal beliefs, in their background, in their philosophy, in their religion or lack of religion, whatever it may be. And most people, it’s very hard for them to see this in a very neutral, unbiased manner. There are two categories of thoughts. One is that actually what makes Sam Parnia into who he is and Paul Rand into who he is and every listener is somehow produced by the brain. So somehow electrical or chemical processes in the brain lead to your thoughts, lead to your sense of awareness, and your consciousness.

The problem with that is, there is no science that supports that. There is no evidence that shows us how... Think about it. A single brain cell could suddenly, which normally produces proteins. Anyone who studied cell biology will know, even at high school, cells produce proteins. So how can a brain cell that produces proteins suddenly lead to this incredible phenomena of thought and awareness? And that’s called a problem of consciousness. There is no science to address it. Some people believe that if you somehow connect hundreds or hundreds of thousands or millions of cells together essentially through circuits with electricity, that somehow magically you give rise to consciousness and thoughts. But again, that’s really a deeply philosophical issue, there’s no evidence to support that. There’s never been an experiment, for example, that shows how brains or brain cells can generate thoughts. Thoughts seem to be a different type of matter to what brain cells and any cell in the body can do.

Now, the other category of opinions if you look at the scientific literature, and this includes Nobel Prize-winning neuroscientists like Sir John Eccles, is that actually the brain is an important conduit, but actually your consciousness, your mind, who you are is a separate entity that interacts with your brain. In the same way that when I go on my computer and I log onto the internet, my computer is not the source of the content of the internet. Without the computer, I cannot access it. So you need it. And if I damage my computer, I don’t see signs of the internet, but it doesn’t mean they’re producing it.

Paul Rand: So what happens to this consciousness when we die? In the words of Shakespeare, death is the last undiscovered country, but Parnia is starting to use the tools of science to explore the edges of it. What happens after death? That’s after the break.

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For most of human history, once a person has died, we assumed that nothing would really be happening in their brains. That consciousness was like a light switch. It’s either on or it’s off. But with modern MRI and EEG machines, we’ve made a fascinating discovery. A few seconds after we die, there’s an explosion of activity in our brains. They light up like a Christmas tree, especially in areas associated with dreaming and altered states of consciousness.

Sam Parnia: And essentially what has been discovered is that as people and animals die, the brain flatlines as I said to you. Most of the function is lost. But then suddenly either five minutes before or up to five minutes after, but remember, these are very early studies, we don’t know if this could extend longer, that there is suddenly in some cases a sudden surge of brain electrical activity of a very high frequency that lasts for a very short period of time and then it’s lost again. This may be a brain marker of people having these hyperlucid, hyperconscious recalled experiences of death as they’re going through from life into death itself. And we may have found a signal which further corroborates what these testimonies that have come back from millions of people from around the world.

Paul Rand: What could our consciousness be experiencing during this surge of energy? Parnia has conducted the largest study ever, interviewing people who have come back from the point of death documenting what they experience and looking for patterns. The study is called AWARE-TO.

Sam Parnia: The issue of life and death was pretty clear until the discovery of CPR. What happened is, looking back about 10 years after, it became clear that many people who’ve survived episodes of getting close to death or even their heart stopping and going beyond what I call the threshold of death were recalling very vivid and universal experiences about themselves, which were labeled near-death experiences. And the reason that term came about was because, in the 1970s, people didn’t realize that you could actually biologically go to death and beyond and be brought back to life again. So based on a philosophy that you could never come back from death, they were labeled near-death experiences.

We don’t think that term is accurate anymore. And the term that we now use is a recalled experience of death. And what we know is that people who go into death, and this has been shown now through multiple studies, and we have conducted the world’s largest studies. As you said, the AWARE-TO program involved more than 25 hospitals with 33 investigators mostly in the US and the UK, but we’ve studied thousands of people whose hearts have stopped and who’ve had recollections.

Paul Rand: Incredibly, 15% of participants in the study reported having vivid recalled experiences of death.

Sam Parnia: And what we now know which is fascinating is that as people go through death, either just before their hearts have stopped or after their hearts have stopped, that they go through an inner experience that is completely unique. So although from our perspective, they look like they are not conscious and they’re at best in a coma or they’re going through death. From the person who’s dying’s perspective, they feel that their own consciousness is not annihilated, that it continues to exist but it actually expands. They describe it as if it suddenly becomes vast, something they’ve never experienced before. And at that same moment, they feel like they’re able to gather information about what’s happening to them as if they’re able to perceive from outside the body. And they’re able to describe what doctors and nurses were doing, who were trying to revive them in accurate detail. But at the same time, they’re also gathering information in 360 degrees.

It’s more like a field of information that they’re collecting rather than how you and I are looking at each other through a straight line. It’s a whole massive information that they’re able to collect and both hear and understand and see what’s going on. And then incredibly, what they then undergo is an experience where they’re able to relive every single moment of their life, everything that they have done. And this is sometimes misrepresented as... It’s as if your life flashes past you. That is not a correct description. What they’re really experiencing is every interaction that they’ve had with other living beings, whether human or otherwise, and they’re reliving what they did but also reliving how the other person or the other entity felt and what they experienced as a result of the interactions that were happening. So they’re feeling both perspectives.

So for instance, if they have done something where they hurt somebody else, say they yelled at somebody, they hurt somebody else’s feelings. They relive that, but they’re also reliving the pain and discomfort the other person felt exactly as that person had done but now thousands of times stronger. Equally, if they had done things that were of great help to somebody else and they caused a lot of good feelings in somebody, they’re re-experiencing those same feelings but now thousands of times higher. And importantly, the way they evaluate this is from a prism of morality and ethics.

So again, it’s not like they’re really reliving their life in a here’s a chronology of my life, here’s event A, this is when I went to school, this is my mom, this is my dad, this is when I graduated, this is my wedding, this is my first child. It’s the interactions, but how it’s seen purely from the perspective of how they conducted themselves based upon moral and ethical views so that they end up re-evaluating their lives in a deeply purposeful manner. And they come to recognize that there was a higher purpose to their life, which was to better themselves based upon morality and ethics. And this is completely universal. It doesn’t matter what people believed, it doesn’t matter where they came from, it’s the same overall understanding.

Paul Rand: Now, you’ve just made the point, and I’m sure many people are thinking this, is that it’s going to differ based on cultural issues or religious issues. And you’re saying that’s just not the case, that it’s a universal concept.

Sam Parnia: It’s completely one of the things that really I found more and more intriguing. Again, I want to say that we’ve studied thousands of cases. We’ve analyzed them in incredible detail. We’ve also used all kinds of advanced mathematical methods using machine learning algorithms as a field of artificial intelligence to try to distinguish between these and see if they’re different to other human experiences like dreams or drug-induced hallucinations. And we were able to show with 98% mathematical certainty that these recalled experiences of death are totally different and are unique and that occur in relation to death. But what is really intriguing about them is that the overall concept is the same. It doesn’t matter where people come from, what their background is. The way that the background affects it is how they interpret it.

Equally, if you happen to be an atheist and you didn’t believe in anything, you may say, “I don’t know.” I mean, I’ve had people say, “I don’t know why I had this experience because I didn’t believe in anything. But incredibly, I did have this experience and I don’t know why it happened to me.” It’s almost like they think it should only be happening to other people. What’s also really interesting, and this is a key thing, it’s not just what people say when you study their testimonies, it’s also what they don’t experience. And I have to clarify this because people sometimes misunderstand. I have nothing against religion, by the way, and I’m very respectful of other people’s beliefs and so on.

I’m not trying to make a claim against this or any of the ritualistic aspects of somebody’s religion in any way, shape, or form. But what does come true, what becomes very clear in these experiences is, even if people have adhered to their religious rituals. Let’s say somebody’s gone to a place of worship every week or they’ve conducted various religious rituals of whatever background you can think of. In their death experience, none of those features are ever remembered. What it boils down to is what they did with their lives.

Now, if these were experiences that were being imagined based upon people’s religious or cultural backgrounds, then you would expect people to be highlighting those aspects of their lives. Like, here, I went to church every week, or I went to a prayer, but none of them do. I have not seen a single case where in the review of life that comes out. Equally, if you were, say, a deeply materialistic person, somebody as we see who’s only interested in, let’s say, gaining wealth and money and power and fame and all this, none of that comes through either. So again, if these were constructs of our own mind, we should see a lot more variety in what people say, and we don’t. It all boils down to not what you said you believed, but how you conducted yourself in life.

Paul Rand: As you think through these examples, is this something that is supernatural that’s occurring, or is it something that’s still happening with the confines of the natural world?

Sam Parnia: I don’t believe in terms like supernatural. Forgive me for saying that. By the way, we’ve had a wonderful conversation. I’m not trying to offend you. You’ve been a wonderful host.

Paul Rand: No offense taken.

Sam Parnia: Great. People use these terms for things that they don’t understand. Forgive me. We’re not humble enough, so we don’t understand. So we all, this is clearly supernatural or this is this. I don’t like those terms. The reality is that even our science today has shown that when we die, that most brain processes shut down, but in that process of brain shutting down, is a way to preserve the body. Your brain is still optimized to try to restore life to you through various measures. One of the things that it does is it shuts down its activity to preserve itself when there’s no... Basically, when it’s being starved where there’s no energy, there’s no oxygen going on. But as it does that, it releases certain breaking systems that are normally in place that prevent you from accessing the entirety of your consciousness.

Because think about it, you’d be overwhelmed if you could suddenly process everything that you have in your consciousness. And incredibly, it looks like when we die, these breaking systems are removed, and suddenly the brain is optimized to enable you to access your entire consciousness. Everything you’ve done from your earliest childhood to the moment you’ve died, but then also analyze them based upon these deep, ethical, and moral principles. So the question we have to ask ourselves is: Why is it that our brain, which is always optimized to make the most meaning out of every circumstance we find ourselves, even in death it’s trying to save our life, but at the same time, it’s giving us access to these dimensions of reality that we can’t access?

It’s not like they don’t exist. Technically, your memories and consciousness are somewhere, but you can’t access them, and suddenly in death, it comes out. And why is it that this is happening to everybody and why is it that what matters in death from your perspective is not your job promotion or your wealth and your other things that we were striving for, but that there’s this deep purpose and humanity that seems to come to the fore at that moment?

Paul Rand: All right, wow. So the idea we’re thinking about, where consciousness fits into this, so the idea that it is separate from brain activity, that’s where your research is taking you, is that right? And what’s leading you to that conclusion?

Sam Parnia: There is no doubt that your consciousness and your brain are deeply connected together. The bigger question is: Can your brain produce consciousness? There are many prominent scientists who also argue that most likely the entity we call consciousness, who we are, is a separate, undiscovered scientific entity. It’s not magical, it’s not supernatural. It exists. We just don’t have the tools to yet be able to measure it. We don’t have sensitive enough tools to measure it. But it’s not produced by the brain. It interacts with the brain. And so yes, if you have brain disorders, you lose sight of your consciousness, but equally, it’s a dual relationship. But that when we die, our consciousness is not annihilated. Now, the evidence that you see from our scientific research in people who’ve gone beyond the threshold of death is that again, people experience that their consciousness does not become annihilated.

They experience that it feels... It becomes hyperlucid, more vast, they become more conscious than they’ve ever experienced before, and they’re having a totally new reality and a new experience that occurs in them. So I think that if we want to look at this in an unbiased manner, and I realize this may challenge some people’s opinions and beliefs, we have to look at this with humility and recognize whatever beliefs we’ve had in the past may not have been the complete picture and that science has entered into a completely uncharted new territory and we’re making remarkable discoveries in this new area of life beyond death.

Paul Rand: The questions that come up around this based on your insight are voluminous. What are the biggest questions, whether they’re in science or philosophy or ethics or spirituality that now need to be struggled with as this science progresses?

Sam Parnia: I think there are two broad ramifications. One is medically we have to recognize that society must impose the need to study this and implement this scientific method in order to save people’s lives. There are millions of people who would be saved if our idea of life and death was challenged. Instead of thinking of it as a binary end, that we recognize that we can salvage it even after it’s happened, we would design treatments, we would be able to bring back people after death. That’s key. The second part of this is that all of us have to recognize that our life, even if we are able to restore life as I’ve just said, we’re all going to go through that. And so I find it remarkable that we live our lives and we ignore the question of what happens when we die.

Yet I see people all the time in my work who are heading towards that. They have weeks, days to live. And one day it’s going to be Sam, and one day it’s going to be unfortunately Paul, and one day it’s going to be every single listener to this who’s going to suddenly find that they have a very limited time left of this time that they had. And so it doesn’t make sense for us to ignore the deeper questions about what happens when we die or to dismiss ancient wisdom, ancient philosophy that has existed throughout the world. There’s not a single society who has not asked these same questions as to what happens when we die. What is the higher purpose to life? Is it simply that we eat, sleep, have pleasure, have families, and get success and have a social status? Or is there a deeper purpose to life?

What these testimonies have shown is that, yes, we should be engaged with our lives, we should try to better our lives, we should be able to have pleasure and have social success, families, and so on, but at the same time that there is a deeper purpose to life, which is what many of the ancient traditions have also talked about. And you may call that spirituality. Yes, if we define spirituality based upon what is the higher purpose to life. Again, not the way that mostly unfortunately western world we see spirituality as this mishmash of all sorts of unclear things. But if you think of it at the higher purpose of getting to know what your purpose is and how do we better our humanity, which is what the message that comes out from research in death, I think it would make a huge change to society.

It’s made me highly cognizant and attentive or try to be attentive to every moment because every interaction we have with other people to try to be cognizant of how that is, how am I conducting myself. As somebody once said, “Could I have done a better job in that interaction with others?” And imagine if we all do that rather than being self-focused, but also be focused equally on other people, what a better society it would be. So not only are we hoping to save people’s lives but also this would impact society in a very positive manner.

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