What is Near death experience | Psychology Concepts.

In near death experiences (NDE), people are usually clinically dead, without the Decree of brain death, are supposed to be transported to another dimension of existence, through sensations and visions, return to life and reveal themselves to be transformed, renewed in their attitudes and beliefs.
These experiences have been reported for thousands of years, since the time of Plato, who left logged in his descriptions of similar experiences. Despite these mystical experiences acquire outlines, some scientists still prefer to ascribe this phenomenon to a cerebral hypoxia, condition in which the brain does not receive adequate oxygenation, despite the blood flowing normally, or the effect of certain drugs consumed by the patient.
The expression NDE was created by Dr. Raymond Moody in his book Life after life, released in 1975. In it, the author reports nine sensations shared by those who have experienced this experience: realize something similar to an insect buzzing in the ears; impression of peace and absence of pain; out of body experience; feeling of being inside a tunnel, watching a light at the end of it; sensation of amount over the heavens; show people already dead, especially someone of the family; contact with creatures of the spiritual universe, sometimes identified as God, depending on the religion or culture of the person; vision of life in retrospect, like a movie, from the moment of birth until death; hesitation to return to life.
Some people also are aware, at the moment, the presence of people around him, in the hospital, you will hear a few times the verdict of death itself, report a 360-degree vision and feel their conventional senses if extend. There's always a borderline point, beyond which the person can no longer return to the material existence – a door, hedge or Lake, that act as definitive demarcations between two spheres-, decision usually fits her take. Almost always those who pass by this crucial moment suffer an intense spiritual metamorphosis.
This phenomenon has been increasingly studied by doctors, who with the aid of the descriptions made by his patients can get closer to a growing understanding of consciousness. With the intensification of these events, scientists can no longer reject the debate and investigations on this topic. When technology if increments and massages in the heart, as well as the use of electrical stimulators, bring back people apparently dead, becomes impossible to dodge the discussions and analyses.
The Dutch cardiologist Pim van Lommel decided to meet this challenge, not with mystical speculations, but with a scientific view of the phenomenon of NDE. He brought together interviews with people who have experienced this event and published the results of his studies in the scientific journal The Lancet devoted, generating intense controversy. He challenged 344 patients of ten Dutch hospitals, defined scientifically as clinically dead, proven fact through an EKG.
If these people were not subjected to a resuscitation process in five or ten minutes, it would be impossible to return to life, because the brain does not receive enough blood or oxygen for human survival. Of these patients, 62 individuals, 18% of those who were on the verge of death, claimed to have lived through the near-death experience. The rest nothing remember about these moments of unconsciousness. In the episodes in which it records the phenomenon, the description of the sensations fits perfectly in the parameters singled out by Moody. These experiences were also chronicled by terminal patients, comatose due to accidents, or in attempts to suicides, among other cases.

Sources:

http://pt.wikipedia.org/wiki/Hip%C3%B3xia_cerebral
http://www.hcnet.usp.br/ipq/revista/vol34/s1/116.html
http://pt.wikipedia.org/wiki/Vida_Depois_da_Vida
http://pt.wikipedia.org/wiki/Experi%C3%AAncia_de_quase-morte
http://revistagalileu.globo.com/Galileu/0,6993,ECT483439-1940,00.html
How to Live Forever – Sally Nicholls – Editorial Generation – São Paulo – 231 pp.
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