Afterlife episode or just a brain tick?

Patients who have had a near-death experience often report walking towards a bright light, or a feeling that they are floating above their body - a sensation that has long been interpreted as a religious vision and confirmation of afterlife. Experts now claim it's a surge of electrical activity triggered by the brain in the moments before death, apparent from a study of the brainwaves of dying patients.

"We think the near-death experiences are caused by a surge of electrical energy released as the brain runs out of oxygen," said Lakhmir Chawla, an anaesthesiologist at George Washington University medical centre in Washington. "As blood flow slows down and oxygen levels fall, the cells fire one last electrical impulse. It starts in one part of the brain and spreads in a cascade and this activity gives people vivid mental
sensations."

Many revived patients have reported being bathed in bright light or suffused with a sense of peace as they start to walk into a light-filled tunnel.

A few even say they experienced visions of religious figures such as Jesus or Prophet Muhammad or Krishna, while others describe floating above their own deathbed, observing the scene.

In one of the most famous cases, in 1991, American singer Pam Reynolds reported watching the top of her own skull being removed by surgeons before she moved into a bright glowing realm, including detailed accounts of the surgery and conversations by her surgeons.

Chawla's research involved an electroencephalograph (EEG), a device that measures brain activity, to monitor seven terminally ill people. He noticed that moments before death, the patients experienced a burst in brainwave activity lasting from 30 seconds to three minutes.

The brain activity was similar to that seen in people who are fully conscious, even though the patients appeared asleep. Soon after the surge abated, the patients were pronounced dead.

Chawla's research, published in the Journal of Palliative Medicine, is thought to be the first to suggest that near-death experiences have a particular physiological cause.

Although it describes only seven patients, he says he has seen the same things happening "at least 50 times" as people die.

Other scientific studies suggest that 15-20% of people who go through cardiac arrest and clinical death report lucid, well-structured thought processes, reasoning, memories and sometimes detailed recall of events during their encounter with death.

In Britain, such research has prompted the launch of the Awareness During Resuscitation study, known as Aware, led by Sam Parnia, visiting fellow at Southampton University's school of medicine. "Since the patients (in Chawla's study) all died, we cannot tell what they were experiencing," said Parnia, suggesting the conclusions need to be treated with caution as there was no proof that the electrical surge was linked to a near-death experience.

Chawla is now planning a further study, using much more advanced EEG machines to follow exactly what happens to the brain during death. "Our findings do not really tell us anything about whether there is an afterlife or not. Even if these near-death experiences turn out to be a purely biochemical event, there could still be a God," he said.