What's Happening During A Near-Death Experience?

Some patients brought back from cardiac arrest describe seeing a bright light at the end of a tunnel, or other phenomena known as a near-death experience. Learn how some researchers have tried to explain this in today's episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio, Hey
brain Stuff lorn bog Obam. Here a man recalls plunging
into darkness and seeing a bright light. Here members a
field of flowers, and a figure in white who spoke
to him about his future. The next thing he recalls
is awakening to discover that during the time he had
experienced this vision, he had actually been lying on an

(00:24):
operating table with doctors hovering over him, frantically trying to
restart his stopped heart. You've probably heard stories similar to
this one, which was recounted in an article in New
Scientists back in two thousand six. What this man remembers
experiencing is called a near death experience, or an n
d E. In the medical literature. Reportedly, about ten to

(00:45):
twenty of people who survive heart attacks experience in n
D but written accounts of NDEs go back to ancient times.
Usually they involve euphoria, tunnels, bright lights, ethereal beings, or
some combination of those phenomena. Some people report seeing a
high speed replay of memories their lives flashing before their eyes.

(01:06):
Nobody really knows what n d s are, or how
and why they occur, though, there are wide ranging hypotheses
and opinions. Some who believe in the metaphysical think that
during an NDE, a seriously ill or injured persons soul
leaves the physical body and journeys to the entrance of
the afterlife. There, for whatever reason, their soul is turned
away and sent back to resume earthly life, sometimes with

(01:29):
a newfound insight about life's purpose. Some physicians and neuroscientists
who have searched for a more provable explanation for endes
suspect that they're hallucinations, somehow caused by the process of
the dying brain shutting down. Over the years, some have
theorized the n d s result when the brain is
deprived of oxygen, or when a mysterious and yet unverified

(01:50):
chemical binds itself to neurons in an effort to protect
them from that deprivation, and some think that the brains
impending shut down triggers a flood of endorphins cause euphoria
or electrical discharges in the hippocampus, the brain area involved
in memory. Another theory goes that near death experiences are
caused by side effects of anesthesia or other medications. However,

(02:13):
so far science has failed to come up with an
air tight explanation for NDEs. In the largest ever study
of the phenomenon, published in the journal Lancet in two
thousand one, Dutch physicians interviewed three d and forty four
mostly elderly hospital patients who survived brushes with death in
which their hearts stopped. Though eight percent of them reported

(02:34):
experiencing NDEs, the researchers found no link to the amount
of time that they were in cardiac arrest or to
the drugs that they had been given since then. Study
published in the journal Clinical Care offered yet another possible explanation.
Researchers looked at blood samples taken from fifty two patients
shortly after they'd survived cardiac arrest. The eleven patients who

(02:56):
reported experiencing NDEs tended to have significant higher levels of
carbon dioxide in their bloodstreams. Other studies have linked high
carbon dioxide levels with visual hallucinations, and mountain climbers who
have experienced carbon dioxide spikes at high altitudes have reported
seeing bright lights and having other hallucinations similar to NDEs.

(03:17):
But again the researchers offer a caveat not every patient
in the study who had high carbon dioxide levels experienced
a near death experience. There's also some evidence that NDEs
may have something to do with a psychological process rather
than a physiological process. Studies have found that younger patients,
female patients, and deeply religious patients are more likely to

(03:39):
report NDEs, and that two thousand one Dutch study reported
another intriguing finding. When researchers reinterviewed the twenty three people
who had experienced nd S and We're still alive eight
years later, those people showed significant psychological differences. Most of
them had become more emotionally vulnerable and empathetic towards others.

(04:04):
Today's episode was written by Patrick Jake Tiger and produced
by Tyler Clang. Brain Stuff is a production of I
Heart Radios Has To Works. For more in this and
lots of other theoretical topics, visit our home planet has
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