Near-death experiences (NDEs) continue to fascinate scientists and the public alike.

Survivors of cardiac arrest often report seeing brilliant lights, feeling their consciousness leave the body, or sensing a presence beyond themselves.

Researchers believe these intense experiences might be the brain’s way of responding to life-threatening situations. While we understand the physical processes of death, what happens to the mind in those final moments remains one of neuroscience’s greatest mysteries.

Metro has shared the incredible story of a man named Tom Kearney who was hit by a bus before Christmas in 2009.

He ended up in a coma after his head split open and his lungs burst.

Tom remained in coma for two weeks and claimed to have seen people who had been dead. First, he saw himself in Ireland, in the house of his great-grandfather where he had seen his deceased grandparents. He recalled they telling him he wasn’t supposed to be there.

All of a sudden, he was shown a gate that took him to New York City at the house of his in-laws. Speaking to Metro, Tom shared his mother-in-law telling him, “You’re not supposed to be here. You’re supposed to be with your wife and your boys, did something happen?”

When he explained he was hit by a bus, his mother-in-law said, “No, no, no, no, you’re not supposed to be here. You’re supposed to leave, you’re not supposed to be here. Please go home”.’

Tom then recalled meeting other deceased relatives, all of whom told him the same thing as his grandparents and his mother-in-law.

He also said he could hear the voices of those who had visited him at the hospital while he was still in coma.

“[My wife] proceeded to talk to me every day. She brought my friends in, my family visited everyone, and they all talked to me.

“This is extremely important because the coma is a bit like you’re in an underwater submarine and you’re trying to steer yourself by sound.

“I was able to construct a thought world that existed in my coma, which was not deeply unpleasant. I went to lots of places in time. Now I have fully consolidated those memories as dream memories.”

Speaking of Tom’s near-death experience, Dr. Charlotte Martial, a neuroscientist with the Coma Science Group and the University of Liege, said she’s fascinated it is a pleasant one since most experiences shared by people who faced death are somewhat negative.

She explained that what most people describe seeing are their loved ones or flash light before their eyes.

The science behind near-death experiences is complex, according to Martial who explains: “So we notably suggest that hypoxia would be the starting point of the cascade of specific neurochemical mechanisms.”

When cells lack oxygen, chemicals are released that may produce experiences such as hallucinations or intense peacefulness. “We list the neurotransmitter change that may lead to specific features, such as the visual hallucination, or the fact that they feel an intense feeling of peacefulness, or the dissociation that happened at that time,” she explains.

In addition to serotonin, other neurotransmitters such as dopamine, noradrenaline, GABA, glutamate, and endorphins play a role, and the resulting sense of calm may act as a protective mechanism.

“This may arise as a defense mechanism when people face a stressful or life-threatening or painful situation,” Dr. Martial added.