Momento mori.

Remember that, you too, will die. 


You are going to die. It is a fact. But what is death going to be like? What happens in those final few minutes of life—and the ones that come immediately thereafter? Survivors of near-death experiences (NDEs) often recount their interactions with the afterlife. Until now, these stories, and the religions they kindle, have been all we’ve had to learn about death. But modern science is beginning to explore what happens to the brain when we die—and is revealing that death is much more complex than we have ever imagined. The brain undergoes mysterious changes in chemistry and electrical activity immediately before and after death. Could these changes explain the stories of bright lights, tunnels, and even heaven itself? How will these discoveries impact religion? Where is the line between life and death, and what impact does that have on end-of-life decisions?

According to critical-care physician Sam Parnia in his book Erasing Death, dying should be seen as “a process, not a moment” (Marantz, 2016). Different parts of the body shut down at different rates, as tissues continue to function until they exhaust their oxygen supply. This is why some living processes, such as excretion, may continue for hours after death is officially declared. The brain, on the other hand, requires intense amounts of energy, making it the first organ to begin to lose power. But as the body slowly shuts down, what is happening inside the brain? Studies have shown unusual patterns of brain activity immediately before death, lending the living some clues into their own post-mortem futures. 

Early stages of oxygen deprivation primarily affect the hippocampus–a delicate structure  of the brain that is responsible for short-term memory. This process explains why many people who experience blackouts during a trauma will not remember the events immediately preceding the injury. Once the hippocampus  loses function, the cerebral cortex, which directs cognition and individual personality, is damaged as well (Marantz, 2016). According to neurologist Cameron Shaw, “our sense of self, our sense of humor, our ability to think ahead— that stuff all goes within the first 10 to 20 seconds [of dying]. Then, as the wave of blood-starved brain cells spread out, our memories and language centres short out, until we’re left with just a core” (Morris, 2017). In these final moments, the brain undergoes a final surge in electrical activity before fading out. Dr. Shaw takes this as evidence that near-death experiences (NDEs), like the light at the end of the tunnel, are simply an illusion propagated by our brains. According to this argument, as the brain regions involved in reasoning begin to falter, strange electrical phenomena create sensations that are often misperceived by the areas of the brain that are still struggling to operate. 

No one knows what actually happens during a near-death experience. Survivors often give accounts that are rich in detail and imagery, sometimes paranormal or heavenly in nature. One of the first recorded instances of a NDE appears in Plato’s Republic, where the Myth of Er describes a soldier who died in battle and remained dead for ten days, only to awaken and share insights into the afterlife with his living compatriots. Indeed, many believe that NDEs contain some of the best clues available about the afterlife, and are even considered by some as evidence of heaven. Many NDE survivors tell of similar sensations: in one study examining the testimonies of survivors, 80% expressed a feeling of being at peace, 69% recalled seeing a bright light, and 63% encountered certain loved ones or figures (Martial, 2017). But are these similarities caused by spiritual or physical transformations? Are they descriptions of a common afterlife or of perceptual “glitches” in the dying brain? 

Some argue that the process of death, rather than making people less aware, raises them to a state of heightened consciousness. It is possible that those experiencing death are perceiving things that the living cannot. A study of brain wave activity in rats in cardiac arrest examined the patterns of gamma-ray oscillations, theta rays, and alpha rays. The results corresponded with normal cognitive function, but occurred at a higher level of intensity, suggesting that information was consciously being processed at a higher-than-normal state of awareness (Borjigin, 2013). 

The idea of varying states of consciousness may sound familiar—brain activity is known to correspond with alternating levels of awareness during sleep. And sleep may lend another clue to how this state of consciousness works; people who have experienced NDEs are also more likely to report a sleep disturbance called REM-intrusion (Lickerman, 2011). REM (rapid eye movement) is a phase in the sleep cycle where the eyes (though remaining closed) move rapidly and randomly. It is also the state in which muscles are relaxed beyond waking control and in which dreaming occurs. REM-intrusion occurs when the REM pattern occurs while awake or awakening, resulting in sleep paralysis—the sensation of being unable to move despite being awake. It is possible that people susceptible to REM-intrusion are more likely to experience NDEs, as their perceptions blur the lines between the different states of consciousness they transition through.

Is death a process? An illusion? With brain-dead patients now able to survive indefinitely on life support, the definition of death is becoming increasingly murky. Some coma patients have exhibited an ability to communicate through deliberately altering their brain activity while undergoing fMRI scans. One patient in particular was able to respond to ‘yes’ to yes/no questions by imagining himself playing tennis, a former hobby. This patient correctly answered five of the six yes/no questions asked of him (one of which had an inconclusive response). Out of the 54 patients tested, five demonstrated evidence of awareness (Monti, 2010). Brain death is diagnosed by the presence of three conditions: coma, apnea, and irreparable loss of brainstem-controlled reflexes. Is it possible that people who are clinically brain dead are still conscious? That they have perhaps been elevated to an otherworldly level of consciousness? These ethical questions have powerful ramifications not only in personal faith, but also in issues as to when it is appropriate to take someone off of life support or to collect organ donations. 

These questions of mortality might never be answered. Perhaps they should never be answered–or only answered in death itself. On his deathbed, Henry Ward Beecher proclaimed his last words, “Now comes the great mystery!”

The one thing that is not a mystery about death?

It stuns us all.


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This article originally appeared in the Emory University Undergraduate Medical Review, Issue of Fall 2017, page 21.

EUMR Publications