I too have read this article, and I will post it if marc is a frightened girl, though i might remove it pending any cease and desist threats from NS.
Joe no longer fears death. In fact the last time it happened he rather enjoyed the ride. First he was plunged into darkness, then came a bright light, a field of flowers, and a man in white who told him about his future. Later doctors informed him that his pulse had been flat for 44 seconds.
For Joe his near-death experience (NDE) was a very real preview of what is in store for him after death. Science has a different take: NDEs are real, but they have nothing to do with the afterlife. Instead, they are illusions created by a fading brain. But despite numerous attempts, no one has been able to scientifically explain all the elements of an NDE.
Now one researcher thinks he can. For Kevin Nelson, a neurophysiologist at the University of Kentucky in Lexington, NDEs may be little more than dream-like states brought on by stress and a predisposition to a common kind of sleep disorder. If he's right, as many as 40 per cent of us could be primed to see the light.
Written accounts of NDEs go back more than two thousand years and have been reported all over the world. Most include a "point of no return" that if crossed will lead to death, and a person who turns you away from it. The identity of the person seems to depend on your religion. Christians, for example, often meet Jesus or a dead relative while Hindus may see Yamraj, god of the dead.
For Nelson, this suggests that NDEs stem from something fundamentally human. "People say that because there's a common thread running through them all there must be a spiritual element," he says. "I look at that common thread and I see a biological process."
Whatever causes NDEs, the experience is surprisingly common. Nearly 20 per cent of heart attack survivors recall at least some elements of an NDE, which can include out-of-body sensations, euphoria, tunnels or a bright light. Half of these people experience full-on NDEs that include several such phenomena. Although they are fairly common, near-death experiences have never been adequately explained. Most rational suggestions trace them back to falling levels of oxygen in the brain, and several explanations have been offered for how this hypoxia might trigger vivid experiences.
Some scientists say that they might be triggered by a hypothetical molecule called "endopsychosin" that binds to neurons and protects them from hypoxia. Others suspect that a flood of endorphins in the amygdala, a part of the brain associated with emotion, could lead to euphoria and feelings of detachment. Falling oxygen levels might also cause epilepsy-like electrical discharges in the hippocampus, which is involved in memory, leading to a rerun of life events. Activity in the amygdala might lend these visions a spiritual tint. Other observers have pointed to painkillers or anaesthetics as possible causes.
In fact, the list of explanations goes on and on. But many of them fail to account for the whole experience and are impossible to test scientifically. Many also overlook the fact that you don't have to be at death's door to have an NDE. A study in 1990 at the University of Virginia Health Sciences Center in Charlottesville of 58 people who had experienced NDEs found that half would have survived without medical care. Sometimes fainting can be enough to trigger NDE-like sensations.
Nelson says that that's because despite the name, NDE has little to do with actually being close to death. He argues that the experience stems from an acute bout of "REM intrusion" - a glitch in the brain's circuitry that, in times of extreme stress, may flip it into a mixed state of awareness where it is both in REM sleep and partially awake at the same time. "The concept that our brain is either 100 per cent awake or 100 per cent in REM sleep is absolutely erroneous," says Mark Mahowald, a neurologist at the Minnesota Regional Sleep Disorders Center in Minneapolis. "We can have pieces of one state intruding into another, and that's when things get interesting."
REM intrusion is a common feature of narcolepsy - a neurological disorder characterised by uncontrollable bouts of sleep that can cause elaborate hallucinations and, sometimes, out-of-body experiences. But REM intrusion can affect anyone, and frequently does. Recent estimates suggest that up to 40 per cent of people have experienced "sleep paralysis", a form of REM intrusion in which you awaken with part of your brain still in REM sleep and your body paralysed. Often the result is a terrifying feeling of being unable to move, accompanied by visual or auditory hallucinations and pressure on the chest. Sleep paralysis has been offered as a rational explanation for many apparently supernatural phenomena, including witch attacks, visitations by the dead, and more recently alien abductions.
Could REM intrusion also explain NDE? "Elements of near-death experience bear uncanny similarity to the REM state," says Nelson. Falling and floating - common in dreams - also occur in NDEs. And although normal dreams fade quickly from memory, that quirky combination of dreaming and wakefulness causes people with narcolepsy to recall their hallucinations vividly. They may remember their NDEs in such clear detail for the same reason, says Nelson. Meanwhile, total paralysis - a hallmark of REM - might make a person believe they really are dead.
REM intrusion could underlie other aspects of NDE, too. "Narcoleptics, whose REM systems often become active while awake, are known to have a propensity for out-of-body experiences," says Nelson, and the frequency of these experiences decreases when their narcolepsy is treated with drugs.
Watching from the ceiling as surgeons work on one's body can be especially convincing during an NDE. Olaf Blanke, a cognitive neurologist at the Swiss Federal Institute of Technology in Lausanne, says these sensations happen when the brain fails to weave different threads of sensory information together. If tactile senses tell the body it is lying down, but a wobbly inner ear causes vision to be interpreted as though from a floating perspective, then a person may well "see" themselves from the ceiling. Blanke has caused people to see their disembodied legs from a floating perspective by electrically stimulating the angular gyrus, a brain area that integrates sensory information. A mixed REM state could disrupt the integration of sensory information in much the same way, says Blanke. The brain may be aware, but the transfer of sensory and motor information from the body is largely shut down.
To investigate the possible link between REM and near-death experiences, Nelson surveyed the frequency of REM intrusion among 55 people who had NDEs in a variety of circumstances, including fainting, heart attack, traffic accident, lightning strike and during surgery. He compared them with 55 healthy volunteers who were matched for age and gender. The results were striking. Around 60 per cent of the NDE group reported having experienced symptoms of REM intrusion, either before or after their NDE, compared with just 24 per cent of the control group. What's more, REM intrusions in the NDE group were more elaborate, including not just sleep paralysis but also hallucinations (Neurology, vol 66, p 1003). "This is good preliminary evidence," says Nelson.
Near-death experiences bear uncanny similarity to the REM sleep state
One fly in the ointment is that REM intrusion is usually a frightening experience, which is hard to reconcile with the often comforting feelings of NDE. In response, Nelson points out that in the context of NDE, REM intrusion happens in a crisis, when our fight-or-flight response has already dampened our normal fear. It's something we can all relate to, feeling strangely detached as a car pile-up unfolds in slow motion, or calmly administering first aid at an accident scene only to panic later. We're naturally prepared, he says, to find the visions comforting.
Not everyone is calm in a crisis, of course, and it is also true that not all NDEs are as comforting as Joe's. Some survivors report hellish encounters that leave them depressed for months afterwards. One woman drifted beyond the stars to an endless void where voices taunted her about the dark eternity to come. A man was tormented by demons who "chattered like blackbirds" about his dangling body after he had hanged himself.
As for the feelings of cosmic unity that accompany the more pleasant NDEs, Nelson points out that the brain's limbic system, which includes the amygdala, lights up during REM sleep. The limbic system is responsible for emotion and some aspects of memory, and studies have long implicated it as a lightning rod - some would say God's rod - for religious experience. Electrical stimulation induces transcendental feelings, and patients with epilepsy whose seizures originate in this part of the brain report experiencing deep spiritual revelations.
Nelson's ideas have been well received by some. "Many of us have thought that REM intrusion was a plausible explanation," says Mahowald, who has spent decades treating narcoleptic patients. "It doesn't take much to extrapolate what we've heard over the last 30 years to near-death experiences."
So if REM intrusion could explain NDE, what explains the REM intrusion? Nelson speculates that the brainstem - which regulates heartbeat, breathing and the sleep-wake cycle - could also be the source of NDEs. In many physiological emergencies such as heart attack, fainting or near drowning, blood pressure or blood oxygen levels quickly drop, or levels of carbon dioxide in the blood quickly rise. This stimulates the vagus nerve, which connects the heart and lungs to the brainstem. According to Nelson, this could cause the REM centres in the brainstem to snap on without warning.
There is some evidence to support the connection. Stimulating the vagus nerve in cats pushes them into REM sleep within 45 seconds. And epilepsy patients whose condition is treated with implants that stimulate their vagus nerve also slip more quickly into REM during daytime naps.
If a few zaps from the vagus can tickle REM centres into action, then this could explain why fighter pilots who black out because of low blood pressure in the brain during high-g accelerations often experience visions of beautiful places, euphoria, out-of-body sensations and weightlessness.
The vagal connection gains further support from a study published in 1994 by Thomas Lempert, then at the Rudolph Virchow Clinic in Berlin, Germany, in which volunteers made themselves faint through a combination of hyperventilating, standing and breath-holding. Many of them experienced euphoric NDE-like sensations such as floating out of their body, entering another world, or encountering supernatural beings. Nelson believes this is a powerful example of how even benign cardiovascular changes might induce REM intrusion and subsequent NDE - even if death is unlikely.
Hypotension could also directly evoke out-of-body sensations. The brain's temporal-parietal junction, which is known to cause such sensations when it malfunctions, is located at the far end of a tree of blood vessels. "So if blood pressure drops," says Blanke, "perfusion in this area is first to go. That could be one reason, purely anatomically, why out-of-body experience is related to NDE."
REM intrusion could even explain the biggest mystery of NDEs: that they seem to occur at a time when the brain is hypoxic and brainwaves recorded from the scalp are flat. "That is definitely paradoxical," says Bruce Greyson, a psychiatrist at the University of Virginia in Charlottesville, who has studied NDE for 30 years. "I don't see any way around this paradox except to say that either our observations of NDEs are mistaken or our models of brain and mind are inadequate."
REM intrusion could solve the problem. The REM centres reside in the brainstem, and while the higher brain areas in the cortex quickly blank out during hypoxia, the more primitive brainstem remains active for several minutes. Whether in fact the brainstem alone could account for NDE without help from the cortex, which normally handles vision and hearing, is anyone's guess, but there is another possibility: an NDE that seems to last many minutes might occur in the few seconds right before or right after the cortex blanks out. "It is likely that NDEs do not appear in real time," says Mahowald, "they may actually be brief, but perceived as prolonged." REM dreaming, which is notorious for compressing time, could be the culprit.
Not everyone is convinced. Greyson maintains that the protocol for Nelson's survey - recruiting NDE subjects on the internet - could have artificially elevated the frequency of REM intrusion in that group. "Those who report their NDEs on the internet may be more likely to admit to unusual things happening to them," he says.
Greyson also questions the conclusion that more REM intrusion in people who have had an NDE means that the phenomenon causes NDE. "It may be more plausible," he says, "that NDEs played a role in subsequent REM intrusion." It is known, for example, that people with post-traumatic stress disorder subsequently have more frequent REM intrusion - maybe because they sleep less soundly. But "if NDE enhances subsequent REM intrusion," responds Nelson, "then that would tell me that NDE and REM are related." He believes this is a testable hypothesis and encourages other researchers to investigate.
He is already planning further tests of his own. He wants to monitor REM activity in the brains of people he expects to experience NDE-like symptoms under certain conditions and record any reports of tunnels, lights and so on. For the moment, though, he won't reveal exactly how he plans to go about this.
The definitive scientific explanation for NDEs may be a little way off, but if, as Nelson's work suggests, many of us are in line for a talk with the man in white, perhaps we should make use of the time we have left to come up with some really good questions.