Light at the end of the tunnel
When close to death many people have reported some odd sensations and visions. For example they may see a long tunnel with a bright light at the end beckoning them to move through it. Along the way they might encounter friends and relatives who have died, and God.
Some have reported encountering events from earlier in their lives (life review). Not surprisingly this can be a highly emotional experience, and many who have come through it have reported feeling elated. Some, however, have reported seeing Satan through the tunnel... and were not so elated!

Sometimes this is accompanied by a sensation of rising up and floating above the body, and being able to look down upon it and at the world. This is referred to as an out of body experience (OBE). Some have argued that it must be the soul which detaches itself from the body.

The whole experience, or a part of it, is known as a near death experience (NDE). It is in fact rare for all the parts to occur in the same NDE.

The experience has become more common with the improvement of cardiac resuscitation techniques. Even by 1992, according to a Gallup poll, approximately eight million Americans reported having had an NDE. It should be born in mind, however, that only a minority of resuscitated patients experience an NDE. A 13 year Dutch study found that 18% of the latter experienced something approximating an NDE. (1)


“It will be a long time before we fully understand the NDE, but it's an incredibly fascinating and profound experience for the people that have it and it would certainly be a mistake for science to close its eyes towards those kinds of experience.”


Chris French
Sweetness and light (but not for all)
NDEs are often accompanied by positive feelings such as a sense of blissful peace, a heightened sense of purpose, greater self-understanding and reduced fear of death. Some report feelings of spiritual awakening and fulfillment. Earlier studies emphasized these positive aspects of NDEs (e.g. Raymond Moody, 1975).(2) However, according to some estimates as many as 15% of NDEs are hellish (Blackmore 2004) (3), some involving torture by elves, giants or demons. Some patients suffered from post-traumatic stress symptoms because of them.
Evidence of an afterlife?
Similarities in these experiences from country to country, or culture to culture, have led some to interpret NDEs as strong evidence of an afterlife. Some even see the good and the bad NDE trips as evidence of heaven and hell. Scientists are not in a position to offer proof or disproof of this theory, and would not normally concern themselves with matters such as the afterlife, since it is impossible to test conclusively. Scientists can, however, at least consider possible natural explanations for the strange experiences.

Drugs and NDEs Some researchers into paranormal experiences, such as Professor Chris French, have pointed out that you don’t need to be dying to have an NDE, and that virtually all the aspects of the NDE have been reported in other contexts. Certain drugs for example, including anaesthetics, can mimic the features of an NDE; and people suffering from psychosis may also sometimes have them, as a result of the severe neurochemical imbalance.

OBEs are quite common in dreams and daydreams, or when semi-conscious due to trauma. They have also been induced by electrically stimulating the part of the brain where the temporal and parietal lobes meet.

False memories could also play a part. Chris French recounts evidence that some who initially reported near-death experiences said in follow-up interviews that they hadn't had them, while others who had said they experienced nothing, said later that they now remembered them.(4)


Why we might see lights as the brain begins to close down
One theory is based upon the firing of nerve fibres in the dying brain as it begins to close down. When we get close to death, the brain starts to lose oxygen, causing strange sensations. The nerves in the brain start to fire irregularly in the area known as the visual cortex (at the back of the brain). The more we lose oxygen the more the nerves fire.

This random firing of nerves is detected within the optic system and translated into visual experiences, in particular the sensation of lights. (It is well known that vision can occur within the optic system - i.e. without any external visual stimulus. It is for this reason that you sometimes literally see stars when you get a punch on the nose, as a result of the crossover of nerve impulses into the visual system.) (See also box in chapter 1 - When the brain constructs what we see) In the same way the random firing of nerves could also cause the buzzing and ringing noises which are sometimes heard.

The sensation of movement
The sensation of movement through the tunnel is caused by the growing light which occurs as more and more nerves fire. (When a light gets bigger at night, the sensation is created that you are moving towards it, or it’s moving towards you.) As you come round the oxygen returns, the nerves begin to function normally again, and the light gets smaller. So you feel as though you are returning out of the tunnel. (5)

It is well known that various chemicals or drugs can do very strange things in our brains. To give just a few examples: atropine (which comes from the poisonous deadly nightshade plant) can trigger the hallucination of flying; certain anaesthetics can easily induce out of body experiences; DMT (dimethyltrytamine) can cause the perception that the world is getting bigger or shrinking; and LSD (lysergic acid diethylomide) can create a feeling of oneness with the cosmos and trigger all kinds of hallucinations.    
The deadly nightshade plant which contains the hallucinogenic (and very dangerous) drug atropine.
In the 1960’s and 70’s there were reports of young people on drugs who jumped off buildings to their deaths, believing that they could fly, or who walked into busy roads under the delusion that cars could not harm them.    

Ketamine Karl Jansen (1997) was interested in the side-effects of the drug ketamine. (6)

This was used as an anaesthetic on U.S. soldiers during the Vietnam War, but was abandoned when the soldiers complained about sensations of floating above their body and seeing bright lights.

Experiments showed that injections of ketamine could reproduce all the main features of an NDE including:

  • a sense that the experience is ‘real’
  • a sense of being dead
  • OBEs
  • visions of loved ones
  • life review
  • spiritual or mystical experiences

Case Study - Dr. Eben Alexander, neurosurgeon
When the neurosurgeon Dr. Eben Alexander, a devout Christian, had bacterial meningitis, he fell into a coma and nearly died, and while in the coma he experienced visions of such intense beauty that it changed his life. His experience was proof enough for him that consciousness is independent of the brain, that death is an illusion, and that a realm of eternal and perfect splendour and bliss awaits us beyond the grave. The experience came with the usual angels, departed loved ones, but also white and pink fluffy clouds, butterflies and a beautiful girl. At the time of writing (November 2012) he is about to release a book, Proof of Heaven: A Neurosurgeon’s Journey into the Afterlife, which seems bound for the bestseller list.

Dr. Alexander may well be honest in the description of his experience. Yet it is well known that many reports exist of such experiences occurring during dreams or meditation, under the influence of psychedelic drugs, or in other states of altered consciousness. He evidently rules out any such alternative explanation. Moreover, although he is obviously aware that the brain does funny things when running out of oxygen, he seems fairly certain that this also could not explain his experience.

Dr. Alexander makes other surprising errors of reasoning for someone of his scientific background. He repeatedly asserts that his visions of heaven occurred while his cerebral cortex was “inactivated,” “completely shut down,” “totally offline,” and “stunned to complete inactivity.” His evidence for this is inadequate.

The “shutting down” of his cortex, he argues, was clear from the “CT scans and neurological examinations”. The problem is that “CT scans and neurological examinations” cannot prove neuronal inactivity in the cortex or anywhere else. Alexander makes no reference to data that might have been acquired by fMRI (Functional Magnetic Resonance Imaging), PET scans, or EEG, and does not seem to realize that only this sort of evidence could indeed support his assertion that his cortex was completely shut down.

Also, in the highly unlikely event that his cortex had shut down completely, how can he be sure that his experience did not occur in the minutes or hours when his cortex was “up-booting” and returning to normal functioning?

Remember also, from chapter 1, the problem with anecdotal evidence. When there is no evidence apart from the story told by one person, doctor or otherwise, reliability cannot be established.

Finally, we know how fallible memory can be, and how easily it can be influenced by expectation. For over a hundred years psychologists have shown that what we “see” and “hear” often depends upon culture, context, expectations, earlier experiences and so on, rather than on what actually impinges upon our retinas or ears. Look up, for example, Elizabeth Loftus’s ingenious experiments showing how our recall of real experiences can be transformed in this way.    
OBE studies
Other studies have focused on the OBEs. Those who have described floating above their bodies during an NDE have reported being able to look down and see themselves, others, and everything else in the room, and to hear clearly what the doctors and others in the room were saying. Since they report being able to see so clearly when floating out of the body, could they then see things from up there which those down below could not see?

In experiments designed to test this hypothesis, messages (e.g. a number) have been placed out of sight and visible only to people floating above their bodies; but so far no convincing evidence has been found. One researcher, the parapsychologist Charles Tart (1968), did report a positive result in the Journal for the American Society of Psychical Research. However, even he had doubts about the validity of his study, since he had earlier seen the five-digit number (which was on a high shelf), and fears he may have communicated this to his subject telepathically! Since this result has not been repeated, we have to ask: could experimenter bias have crept in?

Conclusion: where does the evidence leave us?

  • We know that some people who are close to death experience NDEs
  • We know that some people taking certain drugs, or in other altered states of consciousness, may have similar experiences, including all the features of an NDE
  • The occurrence of NDEs does not prove the existence of an afterlife
  • The occurrence of drug-induced NDEs cannot disprove the afterlife theory, even though all the features of an NDE can be recreated

The scientific experiments can give us pointers but not proof. In the words of Chris French ‘it will be a long time before we fully understand the NDE, but it's an incredibly fascinating and profound experience for the people that have it and it would certainly be a mistake for science to close its eyes towards those kinds of experience.’