Does consciousness exist independently of the brain? Do people have experiences at times when their brains are clinically dead, which they can remember later, so-called “near death experiences” (NDEs)?
If so, how often? What kinds of experiences? Can these experiences be attributed to physiological or pharmacological processes that accompany dying, or to psychological responses to the threat of death, or are they experiences of a reality that transcends the limitations of the flesh body?
In 2001, a small group of British scientists published a pilot prospective study to assess the frequency and possible causes of NDEs in survivors of cardiac arrest. Cardiac arrest survivors were good models for this type of study because they were all resuscitated using a standard procedure and thus all received the same drugs and treatments.
These patients all exhibited at least two of the three criteria for pronouncing a person dead: They had no cardiac output and no spontaneous respiration. In the clinical setting, most of these patients also developed the third characteristic, fixed dilated pupils, as a result of loss of brainstem activity.
Extensive physiological and pharmacological measurements were recorded for all of these patients in the course of their stay in the hospital. Over the course of a year, all cardiac arrest survivors at Southampton General Hospital were identified and interviewed during their stay in the hospital, after the usual safeguards for the protection of research subjects and the integrity of the study had been carried out.
The patients were asked an open-ended question about whether they had any memories about the time when they were unconscious. The experiences of those who reported any memories at all were assessed according to the Greyson standardized scale and divided into the NDE study group and the non-NDE control group.
Of the 63 cardiac arrest survivors interviewed, 56 (88.8 percent) had no memory of their period of unconsciousness. Seven had at least some memory and, of these, four (6.3 percent) had experiences that met the Greyson criteria for NDEs.
Of the three who did not satisfy the criteria, two reported at least one feature consistent with NDEs. Of the four patients in the NDE group, all reported coming to a point of no return. Three of the four also remembered seeing a bright light and feelings of peace, pleasantness, and joy. Half of the four saw deceased relatives, entered a new domain, felt that time had speeded up, lost awareness of their bodies, experienced harmony, and had heightened senses.
None of the patients found their experiences to be traumatic or distressing; rather, they were described as pleasant. None of these patients experienced the out-of-body state.
The patient whose experiences scored highest on the Greyson scale was a male who said he was a nonpracticing Catholic and a Pagan. The other three patients in the NDE group were nonpracticing Church of England females.
Possible physiological causative factors could not be adequately investigated in this pilot study because of the small numbers of patients in the groups. In light of the frequently advanced explanation that NDEs result from oxygen deprivation of the brain, it is interesting to note that the patients in the NDE study group actually had higher oxygen levels than the control group.