Are near-death experiences a dream?
People who have near-death experiences more likely to find REM sleep intruding on reality.
People who have had near-death experiences are more likely to mix up dreams and reality than those who have not, researchers say.
At times of extreme danger or trauma, many people report out-of-body experiences, seeing intense lights, or a feeling of peace. "Near-death experiences are more common than people realize," says neurophysiologist Kevin Nelson of the University of Kentucky, Lexington, lead author of the study published in Neurology1.
Some studies have shown that electrical stimulation to the brain can trigger aspects of near-death experiences (see ' Electrodes trigger out-of-body experience'). Drugs can do the same: ketamine, a horse tranquilizer and illegal recreational drug, can cause many of these symptoms. But spontaneous near-death experiences remain unexplained.
University of Kentucky
Via the Near Death Experience Research Foundation, based in Federal Way, Washington, Nelson found 55 people who reported near-death experiences after traumatic incidents such as car accidents or heart surgery. He also interviewed an equal number who had not had any such experiences.
Of those who reported near-death experiences, 60% also reported having had at least one incident where they felt sleep and wakefulness blurred together. For those without a near-death experience the figure was 24%.
Such blurred periods can include sleep paralysis. Others report visual or auditory hallucinations. Such incidents can occur when some aspects of sleep's dreaming, or rapid eye movement (REM) state, intrudes into wakefulness.
In REM sleep, muscles can lose their tone or tension, inducing a feeling of paralysis. The visual activity during this state may also explain the feeling of being surrounded by light.
REM sleep occurs in the brainstem — the lower part of the brain that attaches to the spinal cord and controls most basic life functions. "Ironically, this most primitive part of the brain may generate experiences that for some is the definition of being human," says Nelson.
He hopes to further investigate near-death experiences by studying people who have had out-of-body experiences independent of any trauma.
Nelson doesn't rule out the possibility that other psychological or spiritual factors may also play a role. "I'm interested in how this experience is generated. That's as far as I take it," says Nelson. As to the ultimate meaning of these experiences, he will leave that question for others to answer.
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- Nelson K., et al. Neurology, 66. 1003 - 1009 (2006).