For hundreds of years, people of all ages, from all over the world, have told similar stories about moments their lives were in real peril: an intense white light, a sense of tranquility and feeling as if they were somehow floating above their body.

For neurologists, these so-called near-death experiences have a neural basis, one that may, according to new research, be similar to what goes on in the brain during certain sleep disturbances.

"I have a theory that near-death experiences may occur when the brain is still functionally and structurally intact," said Dr. Daniel Kondziella, a neurologist at the University of Copenhagen.