Surgeons were about to saw through 80-year-old Aubrey Osteen's chest after a heart attack in December 2020 when he suddenly became conscious.
"I said, 'Wait a minute here before y'all go any further. Give me some more anesthesia, you know?' Well, it took me a minute to realise I wasn't in the same dimension they were in, so they couldn't hear me anyway," he said.
Osteen then watched his body "weave through the rib cage" and float above the operating table while the surgical team cracked his chest, removed the heart and began to repair the damage.
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Soon, he heard someone say "kidneys".
"Both kidneys shut down at the same time — I knew I was gone. And that's when I went to the next level," Osteen said.
"When I got up there, I was in the presence of God – a powerful presence – with light shining from behind him. The light was brighter than anything I've experienced here on Earth, but it wasn't blinding.
"And there was the sweetest angel that comforted me and told me 'Relax. Everything's going to be fine,' and that I was going to have to go back," said Osteen, now 82.
"I know now that I was sent back to tell others about my experience."
What happened to Osteen that winter day is what experts call a "near-death experience".
It can occur when doctors bring a person back to life after the heart flatlines and breathing stops – which happens when a person dies for any reason, not just during a heart attack.
Millions of people have reported near-death experiences since cardiopulmonary resuscitation, better known as CPR, was invented in 1960, said Dr Sam Parnia, an NYU Langone Health intensive care physician who has researched the phenomena for decades.
Parnia is the senior author of a new study designed to uncover what he calls the "hidden consciousness" of death by measuring electrical activity in the brain when the heart stops and breathing ceases.
"Many people report the same experience. Their consciousness became heightened and more vivid, and their thinking became sharper and clearer all while doctors like myself are trying to revive them and think they're dead," said Parnia, an associate professor at NYU Grossman School of Medicine in New York City.
"They have a sensation they have separated from the body and can see and hear doctors and nurses, and they were able to report what doctors were doing to them in a 360-degree way that's inexplicable to them."
In addition, people often review their entire lives, remember thoughts, feelings and events they normally couldn't, and begin to evaluate themselves based upon principles of morality and ethics.
It's a "global comprehension of their behavior throughout life where they can no longer deceive themselves," Parnia said.
People also report seeing a God-like being Parnia says can be interpreted in different ways: "If you happen to be a Christian, you say, 'I saw Jesus' and if you happen to be an atheist, you say 'I saw this incredible being of love and compassion.' All of this has been reported now for more than 60 years."
Recording brain waves while undergoing CPR
In the study, published Thursday in the journal Resuscitation, teams of trained personnel in 25 hospitals in the US, the UK, and Bulgaria followed doctors into rooms where patients were "coding" or "technically dead", Parnia said.
While doctors performed CPR, the research teams attached devices that measured oxygen and electrical activity to the dying person's head.
The average resuscitation attempt lasted between 23 and 26 minutes.
However, some doctors continued to perform CPR for up to an hour, the study found.
"Resuscitation is a very tense, challenging circumstance. It's very high intensity," he said.
"Nobody's ever done this before, but our independent research teams were successful in carrying out the procedures without interfering in the medical care of patients."
Brain activity was measured at two- or three-minute intervals, when doctors had to stop chest compressions or electric shocks to see if the patient's heart would restart, Parnia said.
"There was no movement. It was a silence. That's when we would take measurements to see what's happening. We found the brains of people who are going through death have flatlined, which is what you would expect," Parnia said.
"But interestingly, even up to an hour into the resuscitation, we saw spikes — the emergence of brain electrical activity, the same as I have when talking or deeply concentrating," he added.
Those spikes included gamma, delta, theta, alpha and beta waves, according to the study.
Unfortunately, only 53 people of the 567 people in the study, or 10 per cent, were brought back to life.
Of those, 28 people were then interviewed as to what they could recall from the experience.
Only 11 patients reported being aware during CPR and only six reported a near-death experience.
However, those experiences were categorised along with testimonies from 126 survivors of cardiac arrest who were not in the study, and "we were able to show very clearly that the recorded experience of death – a sense of separation, a review of your life, going to a place that feels like home and then a recognition that you need to come back — were very consistent across people from all over the world," Parnia said.
In addition, the study took the recorded brain signals and compared them with brain signals done by other studies on hallucinations, delusions and illusions and found them to be very different, he added.
"We were able to conclude that the recalled experience of death is real. It occurs with death, and there's a brain marker that we've identified. These electrical signals are not being produced as a trick of a dying brain, which is what a lot of critics have said."
Did the study actually measure consciousness?
"This latest report of persistent brain waves after cardiac arrest has been blown out of proportion by the media. In fact, his team did not show any association between these brain waves and conscious activity," said Dr Bruce Greyson, Carlson Professor Emeritus of Psychiatry and Neurobehavioral Sciences at the University of Virginia School of Medicine in Charlottesville.
"That is, those patients who had near-death experiences did not show the reported brain waves, and those who did show the reported brain waves did not report near-death experiences," Greyson told CNN via email.
Greyson, who was not involved in the new study, is the coeditor of "The Handbook of Near-Death Experiences: Thirty Years of Investigation".
He and cardiologist Dr Pim van Lommel, a Dutch researcher and writer on near-death experiences, submitted comments to the journal to publish alongside the new study.
They pointed to the study's statement that "two of the 28 interviewed subjects had EEG data, but weren't among those with explicit cognitive recall."
"All (the study) has shown is that in some patients there is continued electrical activity in the head that occurs during the same period that other patients report having NDEs (near-death experiences)," Greyson said.
It's correct that the study was not able to match electrical activity with a near death experience in the same patient, Parnia said.
"Our sample size wasn't large enough. Most of our people didn't live so we didn't have hundreds of survivors. That's the reality of it," he said.
"Of those that did live and had readable electroencephalograms, 40 per cent of them showed that their brain waves went from flatline to showing normal signs of lucidity."
In addition, Parnia said, people who survive often have fragmented memories or forget what they experienced due to heavy sedation in intensive care.
"Absence of record doesn't mean there's an absence of consciousness," Parnia said.
"Ultimately, what we're saying is, 'This is the great unknown. We're in uncharted territory.' And the key thing is that these are not hallucinations. These are a real experience that emerges with death."