Contrary to popular perception," Dr Parnia explains, "death is not a specific moment. It is a process that begins when the heart stops beating, the lungs stop working and the brain ceases functioning - a medical condition termed cardiac arrest, which from a biological viewpoint is synonymous with clinical death.
"During a cardiac arrest, all three criteria of death are present. There then follows a period of time, which may last from a few seconds to an hour or more, in which emergency medical efforts may succeed in restarting the heart and reversing the dying process. What people experience during this period of cardiac arrest provides a unique window of understanding into what we are all likely to experience during the dying process."
I have some radical thoughts on death that I posted here: