The near-death experience (NDE) is a profound personal experience associated with death or impending death. NDEs have been reported over centuries and across cultures. Francis Beaufort, the Irishman and British admiral who developed the Beaufort Wind Scale, reported a vivid NDE in 1791, when he nearly drowned.
Scientists no longer question the reality of NDEs, viewing them as unique mental states offering unique/novel insights into the nature of consciousness. The latest developments in this field are described by Rachel Nuwer in Scientific American, June 2024. Although some NDEs are negative (14 per cent), most (75 per cent) are positive experiences very often following the same pattern – the mind “leaves” the dead body and undergoes certain blissful experiences beyond everyday experiences and unhindered by time and space, before returning to the body which then reboots back to life.
Subjects frequently report their minds floating above their pain-wracked body, looking down on it, or even travelling off into space. Travelling through a dark tunnel towards a bright light is commonly reported as is meeting loved ones, living or dead, other beings such as angels or figures such as Jesus. Subjects feel deeply connected to the cosmos and bathed in unconditional love.
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Subjects review their lifetime activities, feel the joy and pain their actions caused to others, and are asked what efforts they made to achieve their purpose in life – growth in wisdom and love. They are then told their time has not yet come and they must return to their bodies, although they dearly wish to remain in this realm. Interestingly, religious people are no more likely to have NDEs than atheists. And in NDE experiences people don’t evaluate themselves on their personal moral standards, but on universal moral standards. After unhappy NDEs, subjects recount visits to hell-like regions and encounters with terrifying voids or demonic beings.
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There is preliminary evidence that people prone to rapid eye movement (REM) sleep intrusion where REM sleep intrudes into wakefulness, blending dreaming and wakefulness, are more likely to have NDEs. But, overall, little is known about NDE neurobiology.
Are they driven by one core mechanism or do they represent a variable response to realisation that death is near? Researchers are now studying the brains of people as they approach/undergo death and have detected a possible signature of NDE in the dying brain.
EEG data was recorded from four comatose patients before and after their ventilators were removed. As brain oxygen levels fell, two of the dying patients showed paradoxical surges of high-frequency brainwaves linked to memory formation and integration. The same thing is seen across the brains of healthy rats during induced cardiac arrest but in humans is confined to a region involved in aspects of consciousness, including visual, auditory and motion processing. This region is also associated with NDEs.
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A large 2023 study provides further evidence of brain activity after the heart has stopped. EEG and brain oxygen data was collected from people during in-hospital cardiac arrest. Interpretable EEG data was collected from about 10 per cent of patients and 40 per cent of these showed neurological activity consistent with transient conscious brain activity up to 1 hour into CPR.
Seventy nine per cent of people who have NDEs report leaving their body and some report seeing things in their environment that are impossible to see normally from their prone body position. Experiments to test such reports are now under way in which unexpected objects/images are placed in hospital resuscitation rooms, some viewable only from vantage points near the ceiling.
Some NDE researchers reject the idea that the mind can exist independently of the brain, holding that when you have an NDE you must have a functioning brain to store the memory and you must survive with an intact brain to retrieve that memory. One alternative hypothesis to explain NDEs is that they represent an aspect of behaviour seen across the animal kingdom where animals feign death when they find themselves in mortal danger, eg in the power of a deadly enemy, but remain conscious and ready to escape should the opportunity arise.
Many religions believe we each have a soul, our non-material essence including identity, personality and memories, often considered synonymous with the mind. Christians believe this soul survives the death of the body. Do NDEs offer evidence of the soul’s existence? If science shows that NDEs are simply hallucinations of the dying brain, then no, but if not, well ...
William Reville is an emeritus professor of biochemistry at UCC