Consciousness exists beyond death and the process of dying should be considered a 'negotiable condition', a bombshell study claims.
Traditionally, death has been defined as the irreversible loss of brain and circulatory function.
But experts are beginning to challenge this view - arguing that consciousness can persist even when the brain stops working.
A researcher from Arizona State University carried out a large-scale review of dozens of studies that focused on what happens when people 'die'.
This included publications on near-death experiences, research on the electrical brain activity of dying patients and clinical studies of conscious awareness during heart attacks.
Analysis revealed that across heart attack studies, 20 per cent of survivors recall conscious experiences during periods when the brain had stopped working.
Brain recordings in dying humans and animals document surges of activity surpassing baseline waking levels, they found.
Meanwhile some patients who have experienced 'complete circulatory standstill' - when the heart stops beating - later demonstrated implicit recall of what was going on around them.
Laboratory work has also demonstrated that metabolism, brain activity and blood flow can be restored in mammal brains and organs 'well beyond accepted limits'.
This reveals that 'biological death is not immediately irreversible', Anna Fowler, from Arizona State University, said.
'Emerging evidence suggests that biological and neural functions do not cease abruptly,' she told the American Association for the Advancement of Science (AAAS) conference in Phoenix.
'Instead, they decline from minutes to hours, suggesting that death unfolds as a process rather than an instantaneous event. Elements of consciousness may briefly exist beyond the measurable activity of the brain and death, long considered absolute, is instead a negotiable condition.'
She added that the findings 'invite a redefinition of death as a gradual, interruptible process, one that science may increasingly learn not just to delay but to challenge outright.'
Ms Fowler, whose research is forming part of her thesis, said the findings could have significant implications for resuscitation windows and organ donation timings.
'After death...they've got to procure those organs right away so that they can save the life of another person,' she explained.
'But there have been studies that have shown that up to 90 minutes after the declaration of death, that those neural firings are still going off in the brain.'
She believes that death should be more 'process driven', with phases rather than a singular event.
'Death, once believed to be a final and immediate boundary, reveals itself instead as a process - a shifting landscape where consciousness, biology and meaning persist longer than we once imagined,' she concluded.
'Consciousness may not vanish the moment the brain falls silent. Cells may not die the moment the heart stops. This research proposes that death is not the sudden extinguishing of life, but the beginning of a transformation, one that medicine, philosophy and ethics must now approach with deeper humility and renewed clarity.'
Earlier this week Dr Sam Parnia, director of critical care and resuscitation research at NYU Langone School of Medicine in New York, revealed that some people may even hear their death being announced as the brain remains active after the heart stops.
Dr Parnia has not only studied what happens to the human brain when you die but has also spoken to patients who survived near-death experiences.
That research revealed many occurrences where patients who were clinically dead, noted as when the heart stops beating, who were later revived and described conversations and events taking place in their room with remarkable accuracy.
The reason doctors only look at the heart when determining the time of death is because that's the moment when blood flow to the brain stops.
However, a study led by Dr Parnia in 2023 discovered spikes in brain waves associated with higher cognitive function up to an hour into CPR. It uncovered spikes in brain waves linked to thinking, memory and awareness showing up to 60 minutes after a person's heart stopped.