Since Raymond Moody first categorised the phenomenon in Life after Life (1975), near-death experiences (NDEs) have become a staple of mass-market publishing. In one common variant, the protagonist (male in all of the examples considered here) finds himself floating above an operating table, looking down on his unconscious body as a medical team struggles to save him. Then he moves on upward, often through a dark tunnel, before emerging into radiant light to be greeted by deceased relations and/or angelic beings. He is told he can choose whether to stay or return, and reluctantly decides to resume his earthly life.
The physiological causes may include a protective rush of endorphins to the brain in extremis (a NDE can be induced with an injection of ketamine), which perhaps explains why the experience is prototypically benign; nobody, as far as I know, has reported a descent into hell and torment. Like lucid dreams, notably dreams of flying, they seem to occur very close to the threshold of consciousness; hence the sensation of falling back into the body at the instant of waking, and the lasting impression they leave. Many people have said that their fear of death remains markedly diminished years after an NDE. But while Moody, despite the implications of his book’s title, insisted that NDEs were entirely subjective, later authors have claimed them as direct revelation.