http://www.skepdic.com/nde.html
Om "ljuset i slutet av tunneln":
Skeptics, on the other hand, believe that NDEs can be explained by neurochemistry and are the result of brain states that occur due to a dying, demented, extremely stressed, or drugged brain. For example, neural noise and retino-cortical mapping explain the common experience of passage down a tunnel from darkness into a bright light. According to Susan Blackmore, vision researcher Dr. Tomasz S. Troscianko of the University of Bristol speculated:
If you started with very little neural noise and it gradually increased, the effect would be of a light at the centre getting larger and larger and hence closer and closer....the tunnel would appear to move as the noise levels increased and the central light got larger and larger....If the whole cortex became so noisy that all the cells were firing fast, the whole area would appear light. (Blackmore 1993: 85)
Om utomkroppsliga upplevelser:
While neural activity might explain bright lights, buzzing noises, and hallucinations, there are some aspects of some NDEs that remain puzzling. Some people who are thought to be dead, but are actually just unconscious, recover and remember things like looking down and seeing their own bodies being worked on by doctors and nurses. They recall conversations being held while they were "dead." Of course, they weren't dead at all, but they feel as if their mind or soul had left their body and was observing it from above. Those who have had such experiences--and they are many--often find them life-altering and defining moments. They are convinced such experiences are proof of life after death by a disembodied consciousness. But are they? It is possible that a person may appear dead to our senses or our scientific equipment but still be perceiving. The visual and auditory perceptions occurring while unconscious-but-perceiving may be produced by a variety of neuronal mechanisms. In fact, we now have evidence that patients who appear brain dead may in fact be capable of conscious thought.
Furthermore, NDE stories are now known to a large audience. Thus, when new stories are told about going into the light, etc., one has to be concerned that these stories may have been contaminated. They may reflect what one has heard and what one expects. Such experiences are still subjectively real and may have profound effects on a person, but they should not be taken as strong evidence of separation of body and spirit, much less of life after death.