Near-death experiences are important but they are not the afterlife, according to a cardiologist

• Michael Sabom is a cardiologist who retired last year.
• He started studying near death experiences — or NDEs — in the 1970s.
• One particular case solidified his belief in out of body experiences.

This as-told-to essay is based on a conversation with Dr. Michael Sabom, who stars in the new film "After Death." It has been edited for length and clarity.

I was doing my medical residency during the 1970s when a social worker introduced me to one of the first books written about near-death experiences — or NDEs. I thought the whole idea was absolute hogwash.

But the social worker challenged me to investigate rather than just brush it off. I asked older doctors whether they'd heard of NDEs, but they hadn't. Then, I started asking patients. The third one I spoke to had had one of these experiences that I'd been convinced were fake.

That was enough for me to really become interested in NDEs. I focused on the out-of-body experience, where people report floating above or near their bodies while still being able to see and hear what's happening around them. That seemed so far-fetched that I could poke a hole in it easily. As a scientist, I'm interested in documentation. I spent the next five years collecting accounts of out-of-body experiences and comparing them to the medical notes.

One case changed my entire belief system

A patient named Pam Reynolds changed everything. Pam had a very complex, dangerous aneurysm that was about to burst. Because of the position, most doctors wouldn't operate, but we found one doctor in Arizona who would try to save her.

Before the operation, Pam was put in a medically-induced near-death state: her heart and brain weren't functioning; her temperature was reduced to about 65 degrees; all the blood was drained from her head; and her ears and eyes were blocked.

Despite that, Pam heard and saw everything during the operation. She later said "I popped up out the top of my head."

When I interviewed Pam about her experience afterward, she described the bone saw the doctor used as looking like an electric toothbrush. That seemed absurd, but when I requested a picture of the tool doctors had used, I saw she was right.

Pam's experience was anchored within a well-documented surgery. There was no logical explanation for how she could know what had happened. Speaking with her convinced me that out-of-body experiences were a real phenomenon.

There are some things we can't explain

Pam's case shows that we can prove that out-of-body experiences can occur. It was a gift to have this happen in such a controlled environment since the vast majority of out-of-body experiences can't be corroborated.

Yet, the out-of-body experience is only one part of a typical NDE. People also report moving through a tunnel, feeling immense pleasure, and being greeted by their deceased loved ones. I think of these as the transcendental aspects of an NDE. These aspects are self-reported and private. We'll never be able to prove them — we just have to take people at their word.

Learning about NDEs changed how I cared for patients

Hearing stories like Pam's convinced me that I could never be entirely sure that a patient couldn't hear me. I was conscious of the fact that an off-hand comment during surgery or resuscitation could be harmful.

When I'm trying to restart someone's heart, I'm not thinking of NDEs or whether the patient's soul is hovering somewhere above me. But afterward, I wonder.

I've also seen how NDEs stay with patients as they recover. The patients who report NDEs have more will to live and also a sense of peace. They often have a new interest in spirituality.

I don't think NDEs are proof of the afterlife

Sometimes, people point to NDEs as proof of the afterlife. I believe there's a heaven, but it has nothing to do with this research. There is a difference between the true afterlife and these experiences of being nearly dead. NDEs still happen in the life that we live day-to-day, but they connect us to a spiritual realm that we're not normally in touch with.

There's a growing acceptance of NDEs, but they're still hard for many people to acknowledge. Our scientific and medical training is based on material proof — we want to be able to measure something and hold it in our hands. You can't do that with NDEs or the idea that there's consciousness outside the brain, but I've become convinced that doesn't make these phenomena any less real.