Faulty sleep switch may cause near-death experience

The Economic Times

Death is an undiscovered country, Shakespeare said, from whose bourne no traveller ever returns. What about the doughty travellers who go near death but do not die? They may have what’s popularly called a near-death experience (NDE).

Usually brought on by a life-threatening episode such as a car accident or a heart attack, the NDE includes euphoric feelings of extraordinary peace and calmness, a sense of being lifted out of your body and seeing an intense light at the end of a tunnel of darkness.

This does not gel well with the extremely awful view of death and dying that people have. For some NDEs validate the existence of the paranormal — of a peaceful continuum rather than a wrenching termination.

For others, NDEs are the ultimate anodyne, meant to buffer your brain from the bodily trauma of extinction. Since life seems to have programmed us so elaborately for the drama of birth and development, they argue, NDEs could well be life’s way of providing for the final exit in a graceful manner.

But it does not answer why only 20% of the heart attack survivors recall some elements of the NDE. Which brings you to the more down-to-earth explanations including, falling levels of oxygen or hypoxia of the brain triggering the vivid images associated with an NDE.

Some scientists speculate that the brain may contain a novel molecule called endopsychosin that binds neurons to protect them from hypo-oxidative damage. Others point to a flood of body’s feel-good chemicals released from the amygdala, which is the emotional centre of the brain.

As to the re-run of past events that’s traditionally associated with an NDE, this could be due to epilepsy-like electrical changes in the memory circuits.

Recent research indicates a more mundane explanation: A new study from University of Kentucky in Lexington finds that people who have had near-death experiences are generally more likely to have difficulty separating sleep from wakefulness.

The scientists led by neurologist Kevin Nelson found that as many as 60% of those who had been through an NDE, had the rapid-eye movement (REM) state of sleep intruding into their regular consciousness while awake.

These subjects were habituated to weird experiences such as waking up and not being able to move, sudden muscle weakness in their legs, and hearing sounds that no one else hears upon waking or falling asleep, both before and after their traumatic event.

Something similar to NDE does happen in REM sleep, also called paradoxical sleep: Muscles lose their tone and heartbeat and breathing rates change dramatically with rapid eyeball movements. The scientists theorise that in a crisis, the REM-state intrudes on an otherwise awake person creating the illusion of being dead. This also conveys the impression of death to people around that person.

The scientists say such an intrusion might also explain the vivid scenes described by some NDE survivors, such as seeing their own bodies from above during surgery, because it probably activates the brain’s limbic system, which is expected to underlie many of the seemingly paranormal, transcendental and emotional aspects of an NDE.