Near-death experiences are not a new phenomenon. They have occurred for millennia across the world and are more common than we think, explains psychiatrist Dr. Bruce Greyson.

Studies of these experiences have revealed consistent patterns, namely a sense of overwhelming peace and well-being. Those who experience near-death often return profoundly changed. 

While there is still controversy in regard to the cause of near-death experiences, there is acceptance in the medical community that they do occur. Materialist explanations — like lack of oxygen to the brain, or drugs given to people in the hospital — are not supported by data. Scientists continue to seek an explanation. 

BRUCE GREYSON: When I first started looking into near-death experiences back in the late-1970s, I assumed that there would be some physiological explanation for that. What I found over the decades was that the various simple explanations we could think of like lack of oxygen, drugs given to the people and so forth, don't pan out- the data do not support them. And furthermore, the phenomena of NDEs, of near-death experiences, seem to defy a simple, materialistic explanation. When we first started presenting this material in medical conferences, there would be a polite silence in the audience. And now in the 21st century, when we do this, it's rare that doctors don't stand up in the audience and say, 'Let me share my experience with you.' So it's pretty well accepted now that these are common experiences that people have all the time, and that have profound effects. There's still, of course, a lot of controversy about what causes them, but not about the fact that they exist, and are fairly common. I'm Bruce Greyson, I'm a professor emeritus of psychiatry and neurobehavioral sciences at the University of Virginia Medical School. And I've recently come out with a book called "After: A Doctor Explores What Near Death Experiences Reveal About Life and Beyond." 

Near-death experiences are profound subjective experiences that many people have when they come close to death or sometimes when they are in fact pronounced dead. And they include such difficult to explain phenomena as a sense of leaving the physical body, reviewing one's entire life, encountering some other entities that aren't physically present. And at some point coming to a point of no return beyond which they can't continue and still come back to life. When they return they often are profoundly changed by this experience. 

As I started my psychiatric training, I started being confronted by patients' reports of things that I couldn't explain. One happened to me when I was just a few weeks into my training. I was asked to see a patient who had an overdose in the emergency room, and I was in the cafeteria when the page came in and I was eating dinner, and the page startled me and I dropped my fork, spilling spaghetti sauce on my tie. Couldn't wipe it off, so I just covered it over with a lab coat so no one would see it. And then I went down to the emergency room to see the patient, and she was completely unconscious. I could not revive her- but her roommate was waiting to see me down the hall in another room. So I went down to the other room, talked to the roommate for about 15 or 20 minutes, and there was no air conditioning back in the '70s, so I unbuttoned my lab coat, so I wouldn't sweat so much, exposing the stain for about 10 minutes or so. And then I went back to see the patient, she was still unconscious. When I went to see her in the morning, I introduced myself and she stopped me and said, "I know who you are. I remember you from last night." That puzzled me, so I said something like, "Well, I'm surprised, I thought you were unconscious when I saw you last night." And she looked at me and said, "Not in my room. I saw you talking to my roommate down the hall." She sensed my confusion, and started to tell me about the conversation I had with her roommate- where we were sitting, what we were talking about. And finally she said, "And you had a striped tie on with a red stain on it." That just blew me away. I didn't know how to deal with that. I couldn't think of any logical reason, any explanation of how she could have known about that spaghetti stain. Nobody had seen it except her roommate. And she hadn't talked to her roommate since she came into the hospital. 

As a scientist, I knew I had to study this. It didn't make any sense to me, but scientists don't run away from things they don't understand. They run towards them. I never expected to spend so much time looking into near-death experiences. I thought at first it was just a strange anomaly. I'd spend a few years looking at them, find the physiological explanation, and put it behind me. I collected about a thousand cases that people had sent to me about their own near-death experience. Quickly realized that the stories I was getting from people who volunteered their stories to me were the same as the ones from people I interviewed in the hospital. We studied the physiological events around the near-death experience, psychological traits with the experiencers and so forth; trying to find some logical explanation for these events. Most of us are taught that the mind is what the brain does. That all our thoughts, our feelings, our perceptions, our memories are all created by the brain. However, that's not the whole story. And we have hundreds and hundreds of experiences that occur during a cardiac arrest or deep anesthesia, when we know the brain is not capable of functioning well enough to create complex thoughts and feelings and memories. 

Most near-death experiencers say that in the near death experience, their senses were incredibly heightened, and they often report hearing sounds they'd never heard on Earth, and seeing colors they'd never seen before. One person said to me, "It's like trying to draw an odor with a crayon." And when they come back, they don't know how to describe these things because there aren't words for them to describe them, but they talk about their senses being so much more vivid in the NDE. And that gives the experience a sense of being more real than real. More real than this world is. Most near-death experiences are pretty much the same around the world and through the centuries. 

Plenty of the elder wrote about a case like this in Ancient Rome. In the first century, we've gotten examples of near-death experiences from Western Europe from the Middle East, from Asian cultures, Hindu, Buddhist cultures, and from primitive cultures- Australian Aborigines and Native American societies, that sound just like the stories we have today. However, how they describe these phenomenon is influenced by their cultural background. For example, people all around the world will talk about encountering a warm, loving being of light that radiates unconditional love towards them. And if you're talking to someone who is raised in the United States, they may identify this as God or sometimes Jesus, whereas someone who is in a Hindu or Buddhist culture will not use those terms. 

Some of the lessons that near-death experiencers bring back from this event relate to what they find makes life meaningful and fulfilling for them. And the primary thing they talk about, is this sense of being interconnected with other people- about how to make this life more meaningful, more purposeful, more fulfilling. I think a reason, many people find near-death experiences interesting is because they hold out the promise that will explain to us what the soul is, whether there is an afterlife, after our body is decomposed. And I think those are good questions, I don't think that's the most important part of the near-death experience. I think they do tell us something about the possibility of surviving bodily death. But I think the important part of near-death experiences is what they tell us about this life we're in now.