One-in-ten people around the world report having a near-death experience at some point in their life, according to new findings to be presented at the annual meeting of the European Academy of Neurology.
Near-death experiences (NDE) have fascinated humans for centuries, yet their origin and prevalence remain a mystery, say the authors. Such events are defined as “conscious perceptual experiences”, including a wide variety of spiritual and physical sensations such as hallucinating, out-of-body experiences, racing thoughts, and a distorted sense of time. Perhaps most interesting, the researchers note that NDEs occur as frequently in people who are in imminent danger of death, such as a car crash or heart attack, as those who are not.
To determine how such NDEs come to fruition in people around the world, researchers recruited more than 1,000 people from 35 countries using an online crowdsourcing platform. Participants were asked if they had ever had an NDE and, if so, to provide more details via the Greyson Near-Death Experience Scale, a questionnaire that quantifies more than a dozen symptoms. Asking questions such as “did scenes from your past come back to you” and “did you suddenly seem to understand everything,” the survey ranks responses to determine whether or not the respondent did, in fact, have an NDE.
Of the 289 people who reported having an NDE, just 106 were deemed a true NDE by the Greyson NDE Scale. Fifty-five percent believed the NDE as truly life-threatening, while the most commonly reported experiences included abnormal time perception (87 percent), exceptional speed of thought (65 percent), exceptionally vivid senses (63 percent), and feeling separated from or out of their body (53 percent). The researchers also noted nearly three-quarters of overall respondents reported having an unpleasant experience, a much higher rate than previously reported. However, this number nearly halved in those confirmed on the Greyson NDE Scale.
By analyzing previous studies, the authors also found an association between NDEs and rapid eye movement (REM) sleep, a phase during sleep where the eyes move rapidly and the brain is as active as when a person is awake. During this time, dreaming is more vivid and people can experience a state of temporary paralysis.
"Our central finding is that we confirmed the association of near-death experiences with REM sleep intrusion. Although association is not causality, identifying the physiological mechanisms behind REM sleep intrusion into wakefulness might advance our understanding of near-death experiences," said lead researcher Daniel Kondziella in a statement.
It is important to note that the study did not account for religious affiliations or other social and cultural factors that might play a role in how people perceive having an NDE. Furthermore, the authors note that it is difficult to fully implement complex clinical and ethical notions into a simple survey conducted over a very short period of time.
"While age, gender, place of residence, employment status and perceived threat do not seem to influence the prevalence of NDE, there is a significant association with REM sleep intrusion," wrote the authors in an abstract emailed to IFLScience. "This finding is in line with the view that despite imminent threat to life, brain physiology must be well-preserved to perceive these fascinating experiences and store them as long-term memories."