The feelings can occur when the person is hovering near death, but also can be brought about through a variety of physiological, psychological, and experimental means. The most frequent avenue is via oxygen deprivation and hyperventilation. They can also be experienced after a localized epileptic seizure or through the influence of anesthetics. In addition, they can be created artificially by electrically stimulating the brain’s temporal and parietal lobes.
Regions related to our proprioception are activated during OBEs. These regions impact our sense of the relative position of different parts of the body, as well as the effort required to move. Intoxication disrupts proprioception, which is why drunks are unable to close their eyes and touch their nose. Similarly, disrupting this sense causes some out-of-body experiences.
Researchers in London demonstrated this on volunteers. Scientists sat the subjects in chairs and had them peer into goggles connected to video screens that showed the volunteers’ backs. When researchers touched the volunteers’ chests with rods, the subjects felt as though they were removed from their bodies and were observing them from a distance.
Feelings similar to this have been reported by survivors of plane crashes and car accidents, as well as those suffering epileptic seizures. When someone is dying or experiencing a seizure, neurons can misfire, cutting the flow of oxygen to the brain. This screwing with the visual cortex leads to visions of white light, tunnels, and feelings of warmth. These are common in the out-of-body experience’s faith-based cousin, the Near Death Experience.
During such an experience, pupils widen, reducing the depth of field. This means the person sees a bright light, and any persons in front of them seem to be bathed in a pleasant glow. By contrast, any images on the periphery are blurry.
Oxygen starvation also causes failure of organs and tissues, but since the eyes and brain are most sensitive to its effects, they shut down first. The brain stem, meanwhile, is the most resistant to oxygen starvation. Therefore, oxygen starvation will cause vision to fail before causing a loss of consciousness.
Consider what happens when a person faints, which occurs when there is a temporary failure of blood flow to the brain. As the process begins, a fainting victim will notice that everything is turning gray or black. This is because their vision failed before they lost consciousness. Some people also report tunnel vision just before going under.
Most people undergoing an NDE will report they felt themselves being drawn to the light. This may be due to the initial restoration of central vision, followed by the recovery of peripheral vision. This would cause a person to initially see what appeared to be a dot of light at the end of a tunnel. This light would grow as the vision increased, creating an illusion of moving through the tunnel.