The research has been published in the journal Circulation. The research studied 567 men and women whose hearts stopped beating while hospitalised and who received CPR between May 2017 and March 2020 in the US and UK.
25 hospitals in the US and UK participated in the study, called AWARE II. Only hospitalised patients were enrolled to standardize the CPR and resuscitation methods used after cardiac arrest, as well as the recordings made of brain activity.
What is CPR?
CPR is a lifesaving technique, consisting of chest compressions often combined with artificial ventilation, that's useful in many emergencies, such as a heart attack or near drowning, in which someone's breathing or heartbeat has stopped.
Near-death experience?
Survivors reported having unique lucid experiences, including a perception of separation from the body, observing events without pain or distress, and a meaningful evaluation of life, including of their actions, intentions and thoughts towards others, they said.
What are these lucid experiences?
The team found these experiences of death to be different from hallucinations, delusions, illusions, dreams or CPR-induced consciousness.
A key finding was the discovery of spikes of brain activity, including so-called gamma, delta, theta, alpha and beta waves up to an hour into CPR.
Some of these brain waves normally occur when people are conscious and performing higher mental functions, including thinking, memory retrieval, and conscious perception, the researchers said.
These results are evident of the fact that on the brink of death and in a coma, people undergo a unique inner conscious experience, including awareness without distress, an expert said.
What happens at the time of death?
Identifying measureable electrical signs of lucid and heightened brain activity, together with similar stories of recalled death experiences, suggests that the human sense of self and consciousness, much like other biological body functions, may not stop completely around the time of death, Parnia added.
As the brain is shutting down, many of its natural braking systems are released. Known as disinhibition, this provides access to the depths of a person's consciousness, including stored memories, thoughts from early childhood to death, and other aspects of reality.
While no one knows the evolutionary purpose of this phenomenon, it clearly reveals "intriguing questions about human consciousness, even at death," said Parnia.
The researchers noted that although studies to date have not been able to absolutely prove the reality or meaning of patients' experiences and claims of awareness in relation to death, it has been impossible to disclaim them either.
