What Happens To Your Body & Brain During A Near Death Experience?

Odds are pretty high that you haven't personally had a near-death experience — but odds are extremely high that you have a rough idea of what they typically entail, just from having been exposed to books, movies or TV shows that show characters moving towards that white light. In fact, you're probably familiar enough with the phenomenon that you know the major near-death experience (or NDE) tropes: someone undergoes a life-threatening physical trauma, like drowning or a heart attack; this is followed by a sensation that the soul is leaving the body, a sense of calm, a trip down a darkened tunnel with a bright light at the end, and possibly an appearance by a beloved deceased family member and/ or star of The Golden Girls. Sometimes there's a religious figure involved, or a review of the person's life so far; and according to some studies, in 23 percent of cases, the person having the near-death experience (or NDE) doesn't feel like soothed or calm, and in fact feels pulled towards a much shadowier (and much less pleasant) afterlife.

Almost as strange as the experience itself is the fact that most near-death experiences are so uniform — people who had all different kinds of inner and spiritual existences while living regularly describe similar NDEs, and have been doing so for centuries (scholars believe that there are written accounts of NDEs dating from the Middle Ages, if not earlier, and the earliest medical description of an NDE was penned in the 1700s by a French military doctor). According to a Gallup poll conducted in the '80s, 8 million Americans have had a near-death experience, and, as reported in the New York Times, there's "no relationship existed between the experience and a person's religious or cultural background."

If you believe in the afterlife, you might say that everyone's experience is so similar because it's what's actually happening to them — and so of course our experiences on the way to Heaven are similar in the way that our experiences waiting on the TSA line at the airport are similar. But scientific researchers have some other ideas about why most NDEs are so similar, and they have to do with the ways our brains and bodies react to our organs shutting down and preparing for death. Of course, it's worth remembering that most NDE studies are based either on the memories of people who have self-reported NDEs, or rats who, as of yet, cannot tell you about whether they felt they were floating outside the laboratory window as a scientists forced them to inhale car exhaust fumes — so you might want to take every theory with a pinch (or darkened tunnel) of salt. That said, the ideas behind what happens in our bodies as they prepare to die are fascinating.

1. You Don't Actually Have To Be Near Death To Have An NDE

"Near-death experiences" seem like they should only occur when you're moments away from having your body and brain close up shop for good, right? I mean, it's right there in the name! But researcher Dr. Steven Laureys, who studies NDEs, believes that simply perceiving yourself as being near death was enough to trigger an NDE for many people — according to a 2013 research study that he led, "Many individuals having had NDEs were not physically in danger of death suggesting that the perception, on its own, of the risk of death seems to be important in eliciting NDEs."

Laureys told CNN that while we often think of the body of someone having a near-death experience as totally shut down, in fact, the brain is still active — he told CNN, ""There is no evidence there can be conscious experience without brain activity." This means that our brains still function in some capacity during the period of time when we are having NDEs.

This idea contradicts the line of thinking that says NDEs are just a fantasy or dream created by the stress of being near death — Laureys' research (conducted with an admittedly small sample size of six people who had had near-death experiences, eight who had been in comas and felt they retained memories of that time, seven who had been in comas and felt they did not retain memories of that time, and 18 who had had zero experiences with comas or NDEs) found that NDEs were more vivid that dreams or fantasies — in fact, study subjects were able to recall them more clearly than actual conscious life events, like their weddings.

2. The Dying Heart May Cause The Brain Activity That Leads To An NDE

So why do our brains stay conscious to some extent as our bodies begin dying? It would make more sense if, as the body neared death, all the systems became less and less functional — and the brain, with its complex systems of brainwaves and chemicals, would be among the first to quit. So why doesn't that happen?

A 2013 study lead by Dr. Jimo Borjigin of the University of Michigan (conducted on nine rats and zero human beings, natch) used electroencephalograms to analyze brainwaves after they induced cardiac arrest or began suffocating the rats. Researchers found that in the 30 seconds after the rat's heart stopped beating, there was a sharp increase in high-frequency brainwaves called gamma oscillations.

These brainwaves are considered to play a major role in the functions of human consciousness — and the study found that, in the moments after the heart stopped beating, they were more active than they were when the animals were conscious and well. Researchers thought this uptick in brain waves had to do with the brain sending panicked messages to the heart to try to get it to start working again — and that this phenomenon might be behind the vivid visions of NDEs. Of course, the study researchers have cautioned against drawing a cause-and-effect line between rats and humans — but it's certainly worth keeping in mind (literally).

3. ...And That Brain Activity May Cause The Heart To Shut Down More Quickly

But that big wave of messages from the brain to the heart may not actually help us — in fact, they might seriously hurt us. In 2015, University of Michigan's Borjigin published a new study about the brain in the final moments of life — and this one found that the frenzy of brain signals sent to the heart in the final moments of life can actually cause our hearts to fail more quickly, giving emergency personnel less time to work on us if we go into cardiac arrest.

Borjigin's team (still working on rats) found that the flurry of brain impulses actually caused the heart to reach a state called "ventricular fibrillation," which is when the heart is no longer able to pump blood properly. When the researchers were able to sever the connection between the brain and heart (in their experiment, by severing the rats' spinal columns), they found that the rats lived three times as long as rats who had their heart-brain connection intact.

Though the researchers obviously don't recommend severing the spines of real-life human patients going into cardiac arrest, their research could potentially mean that chemicals developed to keep the heart and brain of cardiac arrest patients from communicating with each other might give doctors more time to save patients. So while NDEs can certainly seem more comforting than just everything going blank, they could actually be a symptom of our bodies working against us.

4. The Release Of Brain Chemicals Might Explain NDE Euphoria

The same study found that, before the heart entered ventricular fibrillation, the brain released a wide variety of chemicals, including dopamine (which can make us feel pleasure) and norepinephrine (which increases alertness). Together, this brain chemical cocktail could explain the sense of peace and calmness that many people who have had near-death experiences describe.

5. A Lack Of Oxygen Could Cause Those Visions Of White Light

A common near-death experience symptom with a simpler potential scientific explanation is the darkened tunnel with the white light at the end of it. A 2010 study of 11 cardiac arrest patients who had reported near-death experiences found that many of those patients had high levels of carbon dioxide in their blood — which may indicate oxygen deprivation, a state that has been known to lead to the sensation of moving towards a glowing white light.

While there have been no definitive studies on the phenomenon as it relates to NDEs, many scientists believe that tunnel vision — which occurs when blood and oxygen flow are restricted and the eyes begin to fail — could be the real cause behind that glowing passage to whatever afterlife you believe in (Heaven, Paradise, Valhalla, a really solid burrito restaurant) that people typically see when they are having an NDE.

The Bottom Line

Of course, as interesting as all of these studies are, we can't draw many firm conclusions from them. If you have strong beliefs about what happens after we die and whether or not there is an afterlife, you probably won't be particularly swayed one way or the other by a bunch of stuff that happened after some rats were made to eat poisoned kibble or what have you. But even though science may never figure out exactly what happens when we're dying, we're closer and closer to finding out why so many near-death experiences are the same — and that might be the best we can ask for.

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