Do those famous bright lights at the end of the tunnel have a biological purpose?
Perhaps they’re saying something like: “Come on over, oblivion’s fine, it’s all good.”
In most of the stories we hear about near-death experiences (NDEs), the protagonist makes a last-second return to the living.
If they didn’t see that bright light, maybe they momentarily hooked up with departed loved ones, or floated above their body while doctors thumped on their chests or … saw something that freaked them out.
The latter is known as a ‘distressing near-death experience’. They are particularly distressing when images of hell present themselves, along with a flood of guilt, as sometimes happens.
It’s all an illusion
Good or bad, near-death experiences are profound and emotional events, coloured by the kind of feelings that we tend to describe as spiritual or mystical.
Scientists usually explain NDEs as mere hallucinations brought on by stress or drugs, medicinal and otherwise.
A BBC science report, answering a letter from a curious reader, advised that the sense of a bright light at the end of a tunnel is caused by “excessive activity in the brain’s visual system, and similar tunnels can be induced by hallucinogenic drugs”.
The famed ‘out-of-body experience’ is caused “by disruption in the temporoparietal junction” – part of the cortex that controls our body image. These experiences “can be induced by artificially stimulating that spot”.
When near-death goes all the way
‘Near-death’ is just that. You’ve come back to life after nearly dying and lived to tell the tale.
This makes for a big question: Are NDEs part of the dying process?
A new study published in the Proceedings of the National Academy of Sciences suggests this may be the case.
In the study, Michigan scientists asked: “Is it possible for the human brain to be activated by the dying process?”
Yes, they saw it happen.
When two comatose patients were taken off life support, “a surge of activity correlated with consciousness in the dying brain”.
As their bodies transitioned to death, a burst of gamma activity in the brain was detected.
A gamma wave is said to be the fastest brain activity. It is responsible for cognitive functioning, learning, memory and information processing.
The gamma wave lit up what’s known as the ‘hot zone’. This is the part of the brain that lights up when consciousness is active.
This occurs “in the junction between the temporal, parietal and occipital lobes in the back of the brain”.
This area has been correlated with dreaming, visual hallucinations in epilepsy, and altered states of consciousness in other brain studies.
Experimenting on rats
Ten years ago, researchers from the University of Michigan Medical School induced cardiac arrest in nine rats and monitored their brain activity with an electro-encephalograph.
As reported in The New York Times: Within 30 seconds after clinical death, “each of the rats displayed low-amplitude but very high-frequency waves indicative of a highly aroused brain”.
The NYT said that “activity associated with information processing was eight times what is typically found during a conscious, waking state. Activity associated with sensory processing was five times as high”.
Dr Jimo Borjigin, an associate professor of physiology at Michigan and lead author of the 2013 study, and the latest study, said at the time: “You take away the oxygen, take away the glucose, and at least temporarily there’s this heightened activity.”
The human experiment
According to a statement from Michigan: The team identified four patients who died from cardiac arrest in the hospital while under EEG monitoring.
All four patients were comatose and unresponsive. They were ultimately determined to be beyond medical help and, with their families’ permission, removed from life support.
Upon removal of ventilator support, two of the patients showed an increase in heart rate along with a surge of gamma wave activity.
These two patients had previous reports of seizures, but had no seizures during the hour before their deaths.
The other two patients “did not display the same increase in heart rate upon removal from life support nor did they have increased brain activity”.
The meaning of it all
Because of the small sample size, the authors aren’t speculating on what these findings mean.
“It’s impossible to know in this study what the patients experienced because they did not survive,” Dr Borjigin said.
“However, the observed findings are definitely exciting and provide a new framework for our understanding of covert consciousness in dying humans.”
