Death is perhaps the only thing we are promised in life. And yet, despite how natural and inevitable it is, it remains one of the most elusive subjects in modern neuroscience. Of course, we know what death is. We know what it does to the body: how it stills the lungs, quiets the heart and brings all systems to a halt. What we don't know, however, is how the mind behaves in those final moments.
For decades, we've relied on folklore and personal accounts of near-death experiences for clues. Some people describe brilliant white lights, others recall feelings of pure peace -- and many say they saw nothing at all. But among the most enduring and cross-cultural reports is the idea that your "life flashes before your eyes," a phenomenon researchers call a "life review."
Until recently, this has remained unprovable; half folklore, half hope. But a 2022 study published in Frontiers in Aging Neuroscience caught something remarkable by complete accident: the first-ever glimpse of the brain in the moments just before, and just after, death.
In those few seconds, something happened that looks strikingly similar to a life review.
This study did not begin with death in mind. Rather, the team of neuroscientists were conducting a routine EEG on an 87-year-old Canadian man with epilepsy. The initial purpose of this scan was to monitor his brain activity, in the hopes of better understanding his seizures. But during the recording, the patient suffered a sudden heart attack.
As the authors of the study explained, "After discussion with the patient's family and in consideration of the Do-Not-Resuscitate (DNR) status of the patient, no further treatment was administered and the patient passed away."
In total, the team of researchers captured approximately 15 minutes of brain activity leading up to, during and just after the patient's death. And, in turn, what was supposed to be standard data collection became something the first known recording of a human brain during the process of dying.
This rare and accidental event allowed the researchers to observe, in real time, what happens to the brain as it shuts down. But it was the final 30 seconds before and after the heart patient's heart stopped that something phenomenal happened.
"Just before and after the heart stopped working, we saw changes in a specific band of neural oscillations," said Dr. Ajmal Zemmar, one of the leading neurosurgeons within the study, in a statement to Frontiers in Psychology.
More specifically, the EEG recorded an abnormal surge in gamma waves. These are the highest-frequency among all brainwaves, and they primarily occur within the hippocampus (the brain's memory center). Typically, these oscillations are associated with memory retrieval, dreaming and deep meditation.
This spike in gamma wave activity -- in tandem with other oscillations such as delta, theta, alpha and beta -- created a brainwave pattern that looked remarkably similar to what we see when someone is deeply remembering something, or dreaming vividly.
In light of this unprecedented finding, Zemmar suggests that, "Through generating oscillations involved in memory retrieval, the brain may be playing a last recall of important life events just before we die."
Zemmar notes that this idea -- that our brains might perform a kind of memory replay at the end of life -- aligns with what thousands of people have described during near-death experiences.
In a 2014 study from OMEGA - Journal of Death and Dying, researchers analyzed dozens of these near-death experiences. A consistent theme that emerged was the blurring of "boundaries between space, time and perception." The researchers explain that individuals often experience intense feelings of "joy, happiness, peace, and unconditional love" in these moments. And, often, these are accompanied by something of a panoramic life review.
Fascinatingly, researchers believe that humans aren't the only species whose brains seem to do this. Similar brain wave activity has been observed in rats. A 2013 study published in Proceedings of the National Academy of Sciences showed that dying rodents also experience a sharp increase in gamma oscillations just before death. A 2019 study in Frontiers of Cellular Neuroscience supported the same findings too.
Given these cross-species similarities, Zemmar and his colleagues suggest something spectacular: that no matter the species, mammals may spend their last moments in deep mental reverie. That consciousness, in its final seconds, could be universal in its inward retreat.
It's also likely that brainwaves aren't the only mechanisms involved in this process. It's widely believed that the brain releases large amounts of dimethyltryptamine (DMT) at the time of death. This naturally occurring psychedelic compound can be found in many plants and animals -- and it occurs endogenously within humans.
In fact, a 2018 study in Frontiers in Psychology found that people who were administered this hallucinogen reported experiences that were uncannily similar to that of a near-death experience: vivid imagery, feelings of transcendence, timelessness and unparalleled emotional insight.
Of course, this scan doesn't prove that life reviews are a definitive aspect of dying, nor that they happen to everyone. It was a single case. The patient had epilepsy, which can influence gamma activity on its own. We don't know whether he was truly reliving memories or simply dreaming.
But, while we can't say for certain what exactly the brain is doing when we die, we can speculate that these phenomena -- the surge in gamma waves, the potential DMT release, the reports of life reviews, the similar findings in animals -- may all point to a final burst of meaning-making. That, even as the body begins to shut down, the mind might still be hard at work to give us one last vivid, beautiful experience.
That said, these findings don't diminish the depth of loss, nor do they make grieving any easier in any way. Zemmar himself has spoken openly about how indescribably difficult grief can be.
But, in his statement, he leaves us with wisdom that's less scientific and instead more comforting: "Something we may learn from this research is: although our loved ones have their eyes closed and are ready to leave us to rest, their brains may be replaying some of the nicest moments they experienced in their lives."