Subjects: R and D
It’s hard to know whether Clint Eastwood’s new movie, Hereafter, prompted a recent surge in interest concerning near-death experiences, or whether the flick simply tapped into the surge. Regardless, an otherworldly 15 million American adults claim to have had a near-death experience, according to the results of 1997 survey. That number might be a lot higher now that automatic external defibrillators have become commonplace.
It’s also hard to know what to make of these claims from a scientific standpoint, but there’s no denying that near-death experiences are described in stunningly similar ways by people with diverse cultural, ethnic, and religious backgrounds, and across all age groups, right down to toddlers.
People typically describe a near-death experience as a sensation of floating above one’s body, and/or moving through a tunnel towards a light. Often, there are associated feelings profound of joy and peace, and visions of past experiences or deceased acquaintances. The experience usually ends with a realization that it’s not time to die, and a return to one’s injured or failing body.
Some people who’ve experienced the phenomenon and then manage to recover their health undergo personality changes that they attribute to the experience. Others, as is the case with the lovely French reporter played by Cecile de France in Hereafter, become convinced there is an afterlife.
What have scientists learned about the physiologic underpinnings of near-death experiences? The answer, as you might guess, is not much.
The traditional explanation, first promulgated 25 years ago by British neuroscientist Susan Blackmore, was that cerebral oxygen deprivation caused the experience. She noted that astronauts and fighter pilots experience visual disturbances and cognitive abnormalities during high altitude maneuvers in oxygen-poor environments, and their experiences mimic near-death experiences. Alas, a recent study seemed to contradict her theory by showing that people who had near-death experiences actually had higher oxygen levels in their blood than those who did not.
Earlier this year, a study of cardiac-arrest patients in the Journal of Critical Care reported finding high blood levels of carbon dioxide in patients who had near-death experiences. This condition is known to cause hallucinations and out-of-body experiences, even in people who are not on death’s door.
A second study of dying patients in the Journal of Palliative Medicine found that EEG patterns in dying patients revealed a spike in electrical activity just before they passed away. The surge began in one part of the brain and spread in wave-like fashion to other regions. The study authors postulated that such activity could trigger visual and auditory experiences consistent with near-death experiences.
Other scientists have proposed that areas of the brain which control memory could become activated by severe physiologic abnormalities, and that could explain the recollections some people have as a part of their near-death experience. Similar abnormalities could trigger the release of endorphins which could in turn evoke feelings of joy and euphoria.
As for the actual existence of an afterlife, we’ll leave that discussion to others.