From Nature:
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 Neurology.
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%.
More here.