"After being close to death, some people will report having had an out-of-body experience, having seen a bright light or being passed through a tunnel; all well-known elements of the famous Near-Death Experience," according to the study by Laureys and his team of six scientists.
Raymond and Nadine, both from Belgium, had heart attacks. When oxygen was cut off from their brains, they had out-of-body sensations, Laureys said.
"I felt as if I were sucked out of my body at one point," said Raymond. "I was going through a completely black tunnel, very, very quickly, a speed you cannot express, because you just don't experience it."
When Nadine's heart attack came on, she could see herself from outside her body. "It's as if you are on a cloud, even if it's not really that," she said.
It eluded her control, and that frightened her. She went into a dark hole. "You wonder if you will really return to your body," she said.
A light appeared at the end of Raymond's tunnel. He, too, was at first afraid and resisted. The light was female, and she "communicated" with him.
He surrendered to her. "I realized that I shouldn't struggle, and I let myself go. It was at that moment that the experience took place."
Scientific research on people having NDEs is tough, because the exact instant that they occur is unknown, making them nearly impossible to observe, Laureys said.
It would also be cruel to run brain scans on someone who was possibly facing the moment of death.
So, Laureys and his team studied the near-death memories of people who survived -- in particular those of coma patients -- with the help of a psychological examination.
The Memory Characteristics Questionnaire tests for sensory and emotional details of recollections and how people relive them in space and time. In other words, it gauges how present, intense and real a memory is.
They compared NDEs with other memories of intense real-life events like marriages and births, but also with memories of dreams and thoughts -- things that did not occur in physical reality.
The researchers paralleled new memories with old ones. And they compared the patients who had NDEs with groups of others who didn't.
Memories of important real-life events are more intense than those of dreams or thoughts, Laureys said.
"If you use this questionnaire ... if the memory is real, it's richer, and if the memory is recent, it's richer," he said.
The coma scientists weren't expecting what the tests revealed.
"To our surprise, NDEs were much richer than any imagined event or any real event of these coma survivors," Laureys reported.
The memories of these experiences beat all other memories, hands down, for their vivid sense of reality. "The difference was so vast," he said with a sense of astonishment.
Even if the patient had the experience a long time ago, its memory was as rich "as though it was yesterday," Laureys said.