Most world religions believe in some form of the afterlife even if that belief is based purely on faith. Despite this, scientists are yet to find evidence of life continuing after death. But there are some people who came close to dying who believe they already know the answer.
People who have gone through so-called near-death experiences (NDEs) often share detailed memories that on the surface appear to be supernatural.
NDEs often involve moments of cardiac arrest, severe brain injuries or loss of consciousness.
NDEs are also frequently characterised by visions of light at the end of a tunnel, visions of deceased loved ones or out-of-body experiences.
However, many medical experts believe there are natural explanations behind the phenomena.
The topic was explored by Manchester Metropolitan University (MMU) researchers Neil Dagnall and Ken Drinkwater.
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In an article for The Conversation, they discussed the most likely triggers behind NDEs, such as neurochemical reactions in the brain during a moment of trauma.
Dr Dagnall and Dr Drinkwater said: “In our never-ending quest to understand what happens to us after we die, humans have long seen the rare phenomenon of near-death experiences as providing some hints.
“People who’ve had a brush with death often report seeing and experiencing life-altering events on ‘the other side,’ like a bright white light at the end of a long tunnel, or being reunited with lost relatives or beloved pets.
“But despite the seemingly supernatural nature of these experiences, experts say that science can explain why they happen – and what’s really going on.”
Humans have long seen the rare phenomenon of near-death experiences
According to the researchers, scientists have proposed two types of NDEs that are produced by different sides of the brain.
NDEs resulting from activity in the left half of the brain can lead to an altered sense of time or a feeling of flying.
NDEs produced in the right half of the brain, on the other hand, can result in visions of dead people or hearing voices.
The brain’s temporal lobes might also play a role in NDEs as this part of the brain is involved in processing memories and sensory information.
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The MMU researchers said: “Despite several theories used to explain near-death experiences, getting to the bottom of what causes them is difficult.
“Religious people believe near-death experiences provide evidence for life after death – in particular, the separation of the spirit from the body.
“Whereas scientific explanations for near-death experiences include depersonalisation, which is a sense of being detached from your body.”
Some experts have proposed NDEs are hallucinations triggered by the brain releasing dimethyltryptamine (DMT) when on the verge of death.
DMT is a powerful psychoactive substance often associated with spiritual and mystical experiences.
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However, the evidence is inconclusive even if some scientists believe the body naturally releases DMT at birth and at death.
Another theory has proposed NDEs are caused by a lack of oxygen in the brain – so-called cerebral anoxia.
A lack of oxygen potentially triggers seizures in the temporal lobe that cause hallucinations.
Another popular theory states that NDEs are caused by dying brain cells.
The so-called dying brain hypothesis could explain the hallucinations recalled by many patients.
The MMU researchers said: “Currently, there is no definitive explanation for why near-death experiences happen.
“But ongoing research still strives to understand this enigmatic phenomenon.
“Whether paranormal or not, near-death experiences are extremely important.
“They provide meaning, hope, and purpose for many people, while offering an appreciation of the human desire to survive beyond death.”