In a case controlled study Dr. Kevin Nelson, a neurologist and study author of the University of Kentucky tells that people who have had near-death experiences are more likely to mix up dreams and reality than those who have not. At times of extreme danger or trauma, many people report out-of-body experiences, seeing intense lights, or a feeling of peace.

He feels that near-death experiences are more common than people realize. Nelson began investigating the phenomenon after reading of near-death experiences in which patients' arms and legs were paralysed. He knew that some people experience similar paralysis just before sleeping or just after waking. He identified 55 people who claimed 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.

He explains that among those who clamed near-death experiences, 60% reported having had at least one incident where they felt sleep and wakefulness blurred together. When compared to 24% of people who had no near-death experience. These blurred periods can include sleep paralysis. Others report visual or auditory hallucinations. Such incidents can occur when some aspects of ones dream, or rapid eye movement (REM) state, during sleep 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.