Critical questions: Drugs & Hallucinations
Could NDE’s be explained by something such as medical causes alike drugs, or psychological reasons such as hallucinations, or by natural abilities, biases, or fakery? These are questions that we must address.
Could drugs, either medicinal or otherwise cause or contribute highly to NDEs?  What about other medical conditions such as high fevers of lack of oxygen to the brain? Well we know such factors could affect us in many ways, there are some solid reasons why medical causes do not explain the major data we have presented.
First, A collection of researchers have documented and pointed out there are a large number of cases where no drugs, or at least those that would not affect an NDE, were given to patients. In a large sample by Osis and Haraldsson, only in a low percentage of cases could drugs have been relevant. Of the 425 patients with medical data, 61% received no drugs, while another 19% were given drugs that had no effect on consciousness. The authors of the study concluded that 80% of terminal patients who have had apparition experiences during their illnesses were not affected by drugs. This means only 1/5th could be influenced by medication. 
Second, Morse interviewed 37 children who had been treated with almost every kind of mind altering medication known to pharmacology. He discovered that not one of them had anything resembling an NDE.  there are many cases also of people reporting an NDE with no drugs administered to them,  So even if there was a drugs related link, you couldn’t explain these other NDEs away with medical drugs.
Third, medically induced hallucinations. To account for this accusation, Osis & Haraldsson actually devised a “hallucinogenic index” obtained by factoring high fever over 103 degrees (39.4 Celsius), drugs that affect the mind, past medical history, and diseases such as brain disorders (or injury) or uraemia. This index is far higher than necessary, for the factors that were counted may cause hallucinations but don’t always. These factors affected only 38% of the cases tested, with 62% remaining free of them. Quite remarkably, Osis & Haraldsson found that hallucinatory factors even tended to reduce rather than generate near-death phenomena.  And in Morse’s group mentioned earlier, hallucinations still did not cause any NDEs, even with a girl who was helped to hallucinate. 
Fourthly, there are individuals who have had hallucinations and NDEs and clearly distinguish between the two 
So when it comes to these factors, hallucinations and medical drugs are not an adequate response to NDEs.
Other medical conditions
What about medical conditions such as high fever, cerebral anoxia (lack of oxygen to the brain), temporal lobe stimulation or seizure (when this area of the brain is affected by either process, producing various sensations), or endorphin release (a natural substance in the brain that produces “highs” or mimics certain drugs)?
Can these account for all NDEs? Still the answer is no and we go to our old buddies Osis & Haraldsson for this,Haraldsson specifically checked 442 patients in their study for high fevers. They found that 58% of those who saw apparitions had normal temperatures, and others had 34% had fevers below 103 degrees (39.4 Celsius). Only 8% had fevers over 103 degrees (39.4 Celsius). So fevers, even high ones do not account for most NDEs. 
Schoonmaker reports that the blood oxygen level was measured at the time of his patients’ cardiac arrests, and NDEers had sufficient oxygen present for normal brain functioning.  In Morse’s research, the medical records relative to the lack of oxygen in the blood gasses were consulted. None of the experiencers had any more oxygen deprivation than did those in the control group, who did not report these incidents at all. 
With temporal lobe seizure, epilepsy is not a common factors with NDEers.  The Main response to these alleged explanations, including endorphin release, is the inability of subjective responses to explain the corroborative reports of NDEs, especially the accounting’s go patients outside of their bodies, especially in remote locations, and their knowledge of deceased loved ones that they had no way of knowing they were dead.
So that covers these sort of questions
- Morse, Close to the Light, p183-187
- Osis & Haraldsson, At the Hour of Death, p71, 82-83, Table 3, p219
- Morse, Close to the Light, p21
- Moody, Life After Life, p110; Ring, Life After Death, p211-212
- Osis & Haraldsson, At the Hour of Death, p73, 82-83, 104-105, 156, 188
- Morse, Close to the Light, p21-22
- Ring, Life at Death, p210 referring to Sabina work
- Osis and Haraldsson, At the Hour of Death, p71, Table 3, p219
- Ingber, “Visions of an Afterlife,” p142
- Morse, Closer to the Light, p191-192; Moody, Life After Life, p111; Moody, Reflections of Life After Life, p109; Ring, Life at Death, p213; Sabom, Recollections of Death, p178
- Sabom, Recollections of Death, p173