- A first-of-its-kind study captured a man's brain activity the seconds before and after his death.
- It found brain patterns linked with memory recall, suggesting people see flashbacks upon death.
- It also found brain activity continued for seconds after the heart stopped beating.
A highlight reel of life's memories may flash before your eyes when you die, a first-of-its kind study suggests.
The research, published Tuesday in Frontiers in Aging Neuroscience, describes a man who was connected to brain scans when he suffered a heart attack and died.
The scans, which had never been captured on a dying human before, showed the man experienced the types of brain waves associated with memories, meditation, and dreaming right before — and even about 15 seconds after — his heart stopped beating.
The findings raise questions about when life really ends, and may provide comfort to loved ones of the deceased, lead study author Dr. Ajmal Zemmar, a neurosurgeon now at the University of Louisville, told Insider.
Researchers captured the dying man's brain activity by rare chance
The paper traces back to 2016, when an 87-year-old man with bleeding between his skull and brain sought treatment at a Canadian hospital. The doctors, including Zemmar, removed the clot, but three days later, the man developed seizures.
As is standard, Zemmar said, the medical team monitored the patient with an electroencephalogram, or EEG, to determine the root of the seizures. But before they could determine the appropriate treatment, the man went into cardiac arrest and died.
"This is why it's so rare, because you can't plan this. No healthy human is gonna go and have an EEG before they die, and in no sick patient are we going to know when they're gonna die to record these signals," Zemmar said.
The EEG showed that, 15 seconds before the patient's heart stopped beating, he experienced high-frequency brainwaves called gamma oscillations, as well as some slower oscillations including theta, delta, alpha, and beta. These patterns are associated with concentration, dreaming, meditating, memory retrieval, and flashbacks, ZME Science reported.
"And surprisingly, after the heart stops pumping blood into the brain, these oscillations keep going," Zemmar told Insider. "So that was extremely surprising for us to see."
It took his team of colleagues from around the world five and a half years to publish the study in part because they were waiting to see if any other similar cases cropped up. They only found one similar study on rats in which scientists induced cardiac arrest in the animals while measuring their brain activity.
"It is very hard to make claims with one case, especially when the case has bleeding, seizures, and swelling," Zemmar said, or other complications that could account for the findings. "But what we can claim is that we have signals just before death and just after the heart stops like those that happen in the healthy human when they dream or memorize or meditate."
The findings square with some anecdotal reports of near-death experiences, in which people say life's most intensely emotional moments replay before their eyes. When someone almost dies, Zemmar said, "the brain may still trigger those responses so that these patients perceive that near-death experience with the replay and everything, but then come back."
Previous studies found signs of 'heightened consciousness' at the end of life
Dr. Sam Parnia, an associate professor at NYU Langone Health and author of "What Happens When We Die?," told Insider other studies have shown that when people start to die, "they have paradoxical lucidity with heightened consciousness. This includes a meaningful, purposeful review of their entire lives, which encompasses all their actions, intentions and thoughts — in essence their humanity — towards others."
"This study appears to confirm this by identifying a potential brain marker of lucidity at the end of life," Parnia, who was not involved in Zemmar's study, added. "It may be that as multiple parts of the brain are shutting down with death, this leads to disinhibition of other areas that help humans gain insights into other dimensions of reality, that are otherwise less accessible."
The findings might prompt the medical community to rethink when to declare death
When the heart stops beating, clinicians declare death and proceed with arrangements like organ donation. But this study calls those standards into question, Zemmar said.
"A matter of 15 seconds may not sound all that much, but in medicine, it's not that little," he said. "So if we declare the patient dead when the heart stops and perform organ donation, then do we do it 15 seconds after to let them replay memories? I don't know. This is a question that our study has opened up."
Zemmar said he's already heard from people around the world taking comfort in the findings, even though there's no way to know if the memories that may be recalled are positive or negative or both.
"As a neurosurgeon, we see unfortunately at times, patients that we can't help and we have to be the bearer of bad news to the families, which is very difficult," Zemmar said. "So if I can go and tell them this may be happening in your loved one's brain at this moment, and they're having pleasant memories throughout life with you, that I think is something nice for me personally."