Consciousness after death

The possibility of consciousness after death has fascinated human beings for millennia. For most of that time, the experiences of people on the brink of death were interpreted in mystical or religious terms. However, since the 1970s, scientists have studied near-death experiences (NDEs) to discover how the body and brain function in the last moments of life. Although they have not reached a definitive conclusion on the subject, they have found several common experiences that most people report after being revived from an NDE. Among them are a feeling of peacefulness, a feeling of leaving the body, a period of heightened awareness, and visions of a bright light at the end of a tunnel.

Background

Humans and their ancestors have been burying their dead at least as far back as one hundred thousand years. Many of those buried were interred with goods such as jewelry, bowls, or weapons, suggesting an early belief that these items would be used in an afterlife.

The ancient Greeks were the first to study the idea of near-death experiences, referring to those who had “died” and recovered as revenants. The philosopher Heraclitus considered a revenant to be someone who returned to guard both those in the living world and the world of the dead. In his work The Republic, the philosopher Plato recounts the story of a warrior named Er who was supposedly killed in battle only to awaken at his burial. Er said he felt as if he had left his body and traveled to an afterlife. While Plato used Er’s story to support his view of an afterlife, one of his contemporaries, the philosopher Democritus, believed that near-death experiences were simply the body’s process of slowly slipping away as death approached.

Overview

Although Greek philosophers recorded their views on NDEs, reports of people dying and returning from death in the ancient world were relatively rare as medical technology did not exist to sustain the life of a dying person. That began to change in the late-twentieth century as advances in medicine and technology, such as the use of automated external defibrillators, gave doctors a window of opportunity to revive some dying patients.

Beginning in the 1970s, doctors began to study the idea of consciousness after death from a scientific point of view rather than from a religious or mystical angle. The objective of such study was to establish a definition of death. Prior to the late-twentieth century, death was typically assumed to be the moment when the heart stopped beating and a medical professional could no longer detect a pulse. When a person’s heart stops beating, it also stops the flow of blood to the body’s organs, including the brain. Without blood flow, the brain will eventually cease to function and be unable to carry out the necessary functions to maintain life.

The gap in time between when the heart stops beating and the brain dies has led to differing classifications of death. In most jurisdictions, medical, or clinical death, occurs when the heart stops beating and a person stops breathing. However, using methods such as cardiopulmonary resuscitation (CRP) or a defibrillator, heart and breathing functions can sometimes be restarted before brain function is irreversibly damaged. Brain death is permanent and cannot be reversed. For a person to be declared legally dead, a medical professional must determine that the stoppage of the heart and breathing functions and the death of the brain are irreversible.

An NDE occurs when a person’s heart and breathing stop, but the individual is resuscitated before the brain is irreparably damaged. During this time, some people report similar experiences, such as an overwhelming feeling of peace or the sensation of leaving their body and viewing themselves and their surroundings from the “outside.” Many also report seeing a bright light at the end of a tunnel or meeting with departed loved ones. However, on rare occasions, people reported their NDE was a traumatic event, with feelings of peace replaced by terror or despair. Numerous studies have reported that about 20 percent of people who survived cardiac arrest have reported some form of NDE.

Research into NDEs has shown that the human brain retains consciousness after the heart stops and the blood flow through the body ceases. According to research conducted at New York University’s Langone School of Medicine, the cerebral cortex, the area of the brain responsible for cognition and gathering information from the senses, is fully functional from two to twenty seconds after the heart stops pumping blood to the body.

In another study conducted in 2013, scientists observed in animals that the brain experiences a spike in electrical activity shortly before it dies and ceases to function. This surge put the animals in a hyper-alert state in the moments just before death.

Follow-up studies, including one reported in 2023 in the Proceedings of the National Academy of Science, show that people almost certainly retain some form of consciousness and awareness briefly after clinical death. A study done at the University of Louisville in Kentucky found an increase in gamma-wave activity in the time after the heart stops. Gamma waves are types of brainwaves associated with memory, alertness, and happiness.

Based on the findings from these and other studies, scientists speculate that the shared experiences reported by many people who have had NDEs may be a result of the slowing flow of blood to the brain and the sudden surge of electrical impulses. Astronauts and test pilots who have taken part in centrifuge experiments have reported similar experiences as the blood flow to their brain slows as the force of gravity increases.

Similar reports of people having visions of angels, heaven, or being reunited with loved ones may be the result of the gamma waves occurring in a part of the brain associated with religious or spiritual experiences or simply because some people have been conditioned to expect such images when they die. Conversely, people who have had negative NDEs, such as those who claim to have visions of hell, may have been conditioned to see death as a moment of terror and despair.

Bibliography

Freeman, David. “What Near-Death and Psychedelic Experiences Reveal about Human Consciousness.” New York Academy of Sciences, 28 June 2023, www.nyas.org/news-articles/academy-news/what-near-death-and-psychedelic-experiences-reveal-about-human-consciousness/. Accessed 4 Sept. 2023.

Koch, Christof. “What Near-Death Experiences Reveal about the Brain.” Scientific American, 1 June 2020, www.scientificamerican.com/article/what-near-death-experiences-reveal-about-the-brain/. Accessed 4 Sept. 2023.

Nova, Philip. “Can Consciousness Continue After Death? A Neuroscientific Perspective.” Interalia Magazine, Sept. 2022, www.interaliamag.org/articles/philip-nova-can-consciousness-continue-after-death-a-neuroscientific-perspective/. Accessed 4 Sept. 2023.

Perry, Philip. “After Death, You’re Aware That You’ve Died, Say Scientists.” Big Think, 28 July 2023, bigthink.com/surprising-science/after-death-youre-aware-that-youve-died-scientists-claim/. Accessed 4 Sept. 2023.

The Science of Near-Death Experiences, edited by John C. Hagan, University of Missouri Press, 2017.

“Survival of Consciousness After Death.” IONS, 6 July 2022, noetic.org/blog/survival-of-consciousness/. Accessed 4 Sept. 2023.

Upham, Becky. “Could We Still Be ‘Conscious’ Even After We Die?” Everyday Health, 8 May 2023, www.everydayhealth.com/neurology/could-we-still-be-conscious-even-after-we-die/. Accessed 4 Sept. 2023.

“What Is Clinical Death?” LifeSource, 1 June 2023, www.life-source.org/latest/what-is-clinical-death/. Accessed 4 Sept. 2023.