REM sleep and paranormal phenomena
Lindsay links to an interesting article in the Washington Post - Near-Death Experiences Linked to Sleep Cycles:
As many as 10 percent of survivors of heart attacks report having a near-death experience -- such as feelings of transcendence, being surrounded by light or floating outside their bodies.She also links to the abstract of the paper, a Nature magazine coverage of the connection between near-death experiences and REM sleep and a related article on the connection between sleep paralysis and alien abductions. A year ago, Chris Mooney published a good article on that connection as well:
New research announced yesterday suggests a biological explanation for such phenomena: People with near-death experiences are more likely to have different sleep-wake mechanisms in their brains.
In a study comparing 55 people with near-death experiences with 55 people who had no such experiences, neurologist Kevin Nelson of the University of Kentucky found that people who reported such experiences were also more likely to report a phenomenon known as "REM intrusion," where things normally experienced during sleep carry over into wakefulness. REM is an acronym for rapid eye movement, one of the phases of sleep.
Such people wake up but still feel paralyzed or hear sounds that others do not -- as the vestiges of sleep fall away, those experiences disappear. It is not considered a disorder, but merely a variant of the brain's sleep-wake cycle.
Nelson, who published his findings in the journal Neurology, said the extreme fear or feeling of danger brought on by imminent death might trigger the brain mechanism that governs the transition between sleep and wakefulness, leading people to experience various dreamlike phenomena.
The neurologist added that religious and cultural beliefs clearly influenced near-death experiences, and stressed that his findings only spoke to how such a brain mechanism might work, and not why it would work that way.
Our bodies are paralyzed while we undergo REM sleep, and for good reason (lest we act out our dreams and injure ourselves). But in some small number of cases we can actually start to wake up before paralysis wears off, and yet still remain in a dreaming state. What results is hallucination, often of some extremely scary stuff. It appears that humans have always experienced sleep paralysis and sought to explain it, resulting in well known stories of incubi and succubi--demons thought to sexually attack people in their sleep--as well as related tales from other eras and cultures.