Dr Sam Parnia, director of critical care and resuscitation research at NYU Langone Health School of Medicine in New York City, said those who suffer from a cardiac arrest biologically go through the same process as death.
The doctor said the process sparks a sense of new-found life in those who have suffered a cardiac arrest.
Dr Parnia told the express.co.uk: “When we die we review elements of our life and come back transformed. This ranges from being more engaged in society, increased activity in serving public duty or treating family and friends with extra compassion.
“Your overall wellbeing improves. You become less selfish, more selfless.”
Regarding the physical process, Dr Parnia said: “Death is a process, it is not a black and white moment.
“The final result is we have a deduction of oxygen that gets inside the brain when we are about to die and that causes our brain circuits to shut down and we become unconscious to the outside world.
“When the heart stops, all life processes go out because there is no blood getting to the brain, to the kidneys, and liver and we become lifeless and motionless and that is the time that doctors use to give us a time of death.”
Dr Parnia, who has brought thousands of patients back from the brink, said many people can be alive for hours after they die if they are cold enough.
He said: “Being cold slows the process down as your body temperature drops one centigrade an hour after you die. As your body cools, the longer the chance of bringing back to life goes.
“An ideal environment to suffer a cardiac arrest would be in a lake as this would enable longer duration of survival.”
He said thanks to modern technology and science “death does not have to be limited to philosophy and religion, but it can be explored through science.”