The Jeff Wise Blog

“Go Toward the Light”: The Science of Near-Death Experiences

Modern medicine has proven so adept at saving victims of cardiac arrest that a good number of people are walking around today who at one time or another were considered clinically dead. While this is a good thing in and of itself, it has the side benefit of having generated numerous reports of the shadowy psychological condition that people experience when they’re close to “the other side.” So consistent are these reports — combining the sensation of floating, seeing oneself from an outside perspective, and moving through a tunnel towards light — that they have earned an official moniker, “Near Death Experiences,” or NDEs.

Just what is behind these eerily similar reports? To those of a certain mindset, they are a  supernatural phenomenon, an early glimpse of the afterlife that awaits. To those of a more materialist persuasion, these sensations must be generated by some common brain architecture that gets activated under intense stress. As it happens, this latter view has just received some intriguing scientific backing, in the form of a paper in the latest issue of the journal Critical Care. A key component of NDEs, it appears, is carbon dioxide in the blood. Yes, the same thing that makes Cokes fizzy also makes your life flash in front of your eyes.

According to the report, written by a team of Slovenian doctors led by Zalika Klemenc-Ketis, as many as one-quarter of patients who suffer heart attacks experience NDEs. After examining solutes in the blood of 52 such patients admitted for emergency treatment in Slovenia, they found that those with a higher concentration of carbon dioxide also experienced a higher rate of near-death experiences. (Also significant, though less strongly correlated, was the concentration of potassium ions in the blood).

Klemenc-Ketis and her team did not hazard a guess at a mechanism behind the link. But it’s not entirely surprising that high concentrations of carbon dioxide might be linked to an extreme stress response like NDE. If we stop breathing in fresh air, the level of oxygen in our blood goes down, and the level of dissolved carbon dioxide goes up. These changes are sensed by receptors in the brainstem, the heart, and the carotid artery, which together help trigger the urge to breathe. Though we have no awareness of it, this monitoring is constantly going on at a subconscious level. High carbon dioxide levels stimulate the amygdala, and have been implicated in panic attacks.

That is to say, high concentrations of CO2 are fun in your soft drink, but not in your brain.

Suspicion had already centered on carbon dioxide as playing a role in NDEs, the team leader told a British news station, because “it has been known that in other cases, for example in people at higher altitudes, carbon dioxide might provoke some sort of hallucinations and visions, that could be described as NDE-like experiences.”

Have you ever been in a situation so terrifying, or felt yourself so close to death, that you felt your life flash in front of your eyes? If so, I’d love to hear about it. I’ve never had such an experience myself — at least I don’t think I have — and I would be extremely curious to know what the sensation is like. Do you see your whole life in order, or in snatches? Do you feel great emotion? As far as I know, this phenomenon remains one of the great mysteries of extreme fear.

Filed under: Research

4 Responses

  1. Shayne McDonald says:

    I was about 17 yrs old. I was out surfing big waves off the coast of California. A huge wave sucked me up and then pinned me to the bottom of the ovean floor (about 15 feet down ) the pressure was so strong that it felt as if a 500 pound weight was on top of me. usually when this happans you just remain calm and wait 10 to 15 secound for it to let up and then you swim to the surface. This time it had me pinned for about 45 sec and still had no signs of letting up. At about 1 min I started freeking out thinking 100% I was going to die. All of a suddan my brain turned into a picture book. I had memories from childhood all the way to the present. It was so wierd the thoughts we all visual and there must have been over 100 in a matter of secounds. It felt like I was looking back at my intire life from the day I was born. The dark murky water let up and all I could see was the light at the top of the ocean, I swam like hell and lived another day . I used to think it was BS but believe me it is exactly what I discribed . ( A flash back of you intire life)

    Thanks for reading,
    Shayne

  2. tamara says:

    When I was about nine or ten years old my parents had a deep bathtub size jacuzzi. I was in it by myself and I reached to the bottom to grab something that dropped and my hair got caught in one of the vents/drain. I started to panic but no one could hear me, I couldn’t breath, I could barely move. Then I got real calm and reached under me and pulled the plug out without even thinking about it. It was like I was watching myself from outside of my body. My body rolled itself over so I was face up. Then my vision shot out of the bathtub and it was as if I was shooting through the sky, I was running through the grass in our backyard and then back to the sky and then I was in space and the stars were shooting past me. It was amazing. It stopped for a moment that seemed like a second but also an eternity (not sure how to describe it, time was just weird) and I felt so peaceful. The entire universe was slowly swirling around me. Then it was like I was falling back to earth, away from the stars. It happened so fast; there was this huge weight on my chest. Before I realized it I was “back” in my body coughing and retching. The water had drained enough for my face to be above it. I realized my body felt terrible but it was as if the pain wasn’t really reaching me. Since, I’ve had a few other moments of panic where its like my mind shuts off and its like something else is controlling my body. But I’m always trying to get back to what I felt when I was in space. It was just so amazing, it’s what I imagine a person is supposed to attain through years of meditation.

  3. Jeff Wise says:

    Shayne and Tamara,
    My thanks to both of you for sharing your experiences. They both make incredible reading.
    Jeff

  4. […] (NDEs),  several readers wrote in and described their own brushes with the beyond. Writes Tamara, I started to panic but no one could hear me, I couldn’t breath, I could barely move. Then I got […]

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Thinking About Fear & the Brain

If I find myself in a severe crisis, will I be able to keep it together? How can I control anxiety and panic? Is it possible to lead a life less bounded by fear? These are the sorts of questions that I'll be exploring in this blog, an offshoot of my book, Extreme Fear: The Science of Your Mind in Danger, published on December 8, 2009 by Palgrave Macmillan.

Video Introduction

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