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.
|
