NDEs are markedly different from hallucinations in their contents and effects, as explained below:
NDEs also differ from hallucinations in their scientific causative mechanism. In an article in the medical magazine, The Lancet, Pim van Lommel and her Dutch co-researchers expose a fatal flaw in all such physiological explanations of NDEs: “With a purely physiological explanation [for NDE] such as cerebral anoxia [absence of oxygen] for the experience, most patients who have been clinically dead should report one.” In simpler words, if NDEs are caused by hallucinogenic or physiological conditions, then all people under those conditions should have NDEs. Yet, only some do. This selectiveness of NDEs shows that neither are they hallucinations, nor are they caused by any physiological conditions.
That NDEs are not hallucinations is also evident from the factually accurate information given by many NDE subjects, information that could never have been obtained through hallucinations. Dr Michael Sabom, an American cardiologist who started his NDE research in the late 1970s as a skeptic, gives many such cases that dissolved his skepticism in his books like Recollections of Death: A Medical Investigation. Here are two of them:
A retired Air Force pilot who had suffered a massive heart attack recounted the resuscitation procedure in rich detail. He even described the motions of the two needles of the defibrillator, which is an electronic device used to administer electric shock to attempt to restore the normal functioning of the heart. How could a person who was (1) in the middle of a cardiac arrest (2) about to be jolted by an electric shock (3) while being almost certainly unconscious (4) not in a physical position to observe the defibrillator meter (5) methodically observe the motion of the needles on its dial?
A woman provided a medically accurate and detailed description of her lumbar disk surgery which was performed with the patient in supine position. She reported that her surgery had been performed, to her surprise, not by her surgeon but by the chief resident in neurosurgery, a detail that was correct but had not been divulged to her.
Given such strong scientific reasoning and evidence for NDEs, the hallucination hypothesis can be safely buried deep under the ground.
In conclusion, it can be understood that consciousness is not a property of the brain and “dead matter”.