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What happens after we die? It's a question humans have grappled with since the beginning of time. Some people say they’ve gotten a glimpse into the afterlife during near-death experiences, when their heart stopped during a surgery, accident or emergency.
Skeptics believe these accounts are imaginary, but some doctors are now studying near-death experiences with tools to measure the phenomenon.
Dr. Sam Parnia of the State University of New York at Stony Brook, and author of "Erasing Death," is one of the experts conducting research.
“People who come close to death for any reason typically describe a sensation of being profoundly peaceful and comfortable. Some of them describe a tunnel and a bright, warm, welcoming light,” Parnia told TODAY'S Jenna Bush Hager as part of our two-day "Do You Believe?" series.
“Probably the most interesting aspect of this is that a small group of them describes a sensation of actually separating from themselves and watching doctors and nurses trying to save their lives. Except that they're clinically dead.”
In the AWARE study involving more than 2,000 cardiac arrest patients, Parnia and his colleagues used auditory tests to time consciousness after the brain had shut down.
“What we found is that 40 percent of people had a perception of having had awareness, which was phenomenally high. Ten percent of them had a classical near-death experience and about 3 percent of them actually had full consciousness and awareness and could describe things,” Parnia said.
One man was able to recall details that occurred for up to five minutes after he was declared clinically dead. The brain shuts down within two to 20 seconds in those cases and would not have been functioning, he noted.
Dr. Jeffrey Long, a radiation oncologist and author of "God And The Afterlife," has studied more than 4,000 patients who reported near-death experiences and found a very consistent pattern of elements in the accounts.
“There may be a life review, where they see part or all of their prior life. They may encounter deceased relatives. These are joyous reunions. The two most common words used to describe a near-death experience are peace and love,” Long said.
After people survive, he sees them undergo dramatic change, including an increased belief in the afterlife and a decreased fear of death. Some people even leave jobs where they're forced to act out in materialistic ways. There's a vast amount doctors and others can learn from near-death experiences, Long noted.
But not everybody believes the accounts, dismissing them as hallucinations.
To deepen his understanding, Parnia is now conducting a new study, giving specific sounds through an earpiece to patients in cardiac arrest. Unusual images will also be placed high and facing the ceiling in hospital rooms, so they're only visible to somebody looking down from above — in theory, to a soul separated from a physical body.
“The machines we use will also give visual stimuli, maybe a picture of a cute baby, to see if they can recall them,” Parnia said. “If you come back and say you saw Dr. Smith or Dr. Jones, what they were doing, the question is: will you also see the image that's in the room that is independent? That you would not to have been able to guess because it's not something you'd expect to see on TV.”
Parnia hopes to enroll other hospitals and inspire other doctors to start thinking about how they should be measuring what's happening in the brain.
Some doctors and those involved in the near-death community say that, in general, scientific and medical professionals are increasingly accepting of the concept. No matter what you believe, the research will continue.