Are Near-Death Experiences the Brain's Attempt to Survive Lethal Threats?
NEWS | 01 April 2025
Researchers put forward a comprehensive model outlining the conditions that may give rise to the vivid mental phenomena that some people experience as they near death Everyone dies, but what actually transpires during that process is a deep mystery that scientists are only beginning to seriously investigate. Increasingly, near-death experiences, or NDEs, are part of that growing field. An incredible 5 to 10 percent of the general population reports memories of an NDE. Oftentimes, people’s recollections are similar: perceiving separation from the body and viewing it from above, passing through a tunnel and seeing a light, encountering deceased loved ones or compassionate entities and being overcome by ineffable wisdom and a feeling of profound peacefulness. Many people describe these memories in crisp detail and say that they felt “more real than real.” How a person’s faltering consciousness produces such fantastical experiences is unknown. But scientists have been piecing together hypotheses, constructed from interviews with survivors, studies in animals and experiments in which people were given certain psychedelic drugs. Now one of the preeminent research groups investigating NDEs has published what it describes as the first comprehensive neuroscientific model for the phenomena. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. “We found a very robust explanation for the generation of such a rich experience while a person is really in crisis,” says Charlotte Martial, a neuroscientist at the University of Liège in Belgium and co-lead author of the findings, published this week in Nature Reviews Neurology. Martial and her colleagues’ model lays out a step-by-step hypothesis for the conditions that give rise to NDEs. They also propose an evolutionary theory for why these experiences occur. To create the model, the authors undertook an exhaustive review of all the studies they could find on NDEs, which ranged from neuroscientific investigations to spiritual perspectives. They also included research on ecstatic seizures, psychedelics and the dying brain. Additional clues came from studies that showed that individuals who have certain predispositions are more likely to experience NDEs. This includes prolific daydreamers, as well as those with a propensity for rapid eye movement (REM) sleep intrusion, which occurs when REM sleep bleeds into wakefulness or non-REM sleep. NDEs themselves are triggered by a precipitating event, such as a cardiac arrest, that causes a cascade of physiological stress. The authors propose that certain networks of neurons go into overdrive to produce high levels of specific neurotransmitters in the drastically altered brain environment. The researchers investigated several of those systems and hypothesized ways that they may contribute to distinct mental experiences as the person approaches death. The fact that people can clearly remember NDEs, the authors write, is likely because of the activity of three main neurotransmitters: acetylcholine, which is involved in memory, learning and attention; noradrenaline, which plays a key role in the fight-or-flight response, as well as attention, focus and memory; and glutamate, another learning and memory aid that is also responsible for orchestrating overall brain function by instructing neurons to communicate with one another. Beyond the triad of chemical culprits, the researchers linked the calm, peaceful feeling that characterizes many NDEs with activation of 5-HT1A receptors by serotonin, as well as with transient rises in endorphins—the body’s natural pain relievers and mood enhancers—and GABA, a neurotransmitter that reduces neurons’ activity. For the vivid hallucinations that oftentimes accompany NDEs, the team pointed to serotonin’s hyperactivation of 5-HT2A receptors. Dopamine likewise contributes to the altered visual experience and lends a sense of realism. The new model calls into question a prior hypothesis that a yet-undiscovered, naturally occurring chemical in the brain plays a role in inducing NDEs by blocking the same receptors that the synthetic drug ketamine binds to. Those receptors, however, are essential for memory formation, so if they were blocked, people should not be able to recall NDEs with such clarity, says Nicolas Lejeune, senior author of the new study and a neurorehabilitation clinician and researcher at the University Hospital of Liège. “Instead of assuming the existence of an unknown neurochemical, we propose that NDEs arise from disruptions that naturally occur in response to life-threatening events,” he says. The model does not account for every facet of an NDE. The researchers did not find an explanation for common reports of reliving past memories or having the sense of approaching a point of no return. The team hypothesized that these features may be driven by psychological processes or biological factors that have yet to be identified. More research is also needed to identify the brain regions where the chemical surges that trigger NDEs primarily occur, Martial says, but a 2023 study suggests that the junction of the temporal, parietal and occipital lobes may play a key role. “This is one of the main regions for consciousness,” she adds. Finally, the researchers also put forward an idea for why the brain evolved to react this way. The neurochemical model, they argue, dovetails with other research suggesting that NDEs are the human version of “playing dead.” Many species use this last-ditch survival effort in the face of mortal danger after fight or flight fails. In feigning death, the animal goes limp and becomes unresponsive to external stimuli. But it remains aware of its surroundings, so if given the chance, it can escape. The idea that “playing dead” could be the evolutionary origin of near-death experiences is backed up by the fact that some people who perceived themselves to be in life-threatening circumstances but were not actually physically harmed have reported near death-like experiences. The otherworldly, shared components of these experiences may be the human brain’s attempt to make meaning out of what’s happening. “In a sense,” Martial says, “NDEs are a passive coping mechanism to enhance survival in life-threatening circumstances.” Jimo Borjigin, a neuroscientist at the University of Michigan, who was not involved in the research, disagrees, however, with some of the ideas put forward in the new paper—including the assertion that the mechanisms underlying NDEs are likely to be similar to those that trigger REM intrusions. Although a correlation has been found between people who experience REM sleep intrusions and those who have NDEs, this “is only a hypothesis that is untested by experimental investigations,” Borjigin says. “We do not need hypotheses that are built on another hypothesis,” she adds. “We are at a stage in need of more physiological data.” Martial and her colleagues acknowledge that their new model is only a first step toward creating a more robust framework—one that, ideally, will be supported by physiological data. The hypotheses they lay out for various features of NDEs could be road maps, Martial says, “for future empirical studies that will aim to go into more details.” By investigating the extreme end of human experience, she adds, these future studies could also help to shed light on the mechanisms of consciousness itself.
Author: Gary Stix. Rachel Nuwer.
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