A surge of electrical activity in the brain could be responsible for the vivid experiences described by near-death survivors, scientists report.
A study carried out on dying rats found high levels of brainwaves at the point of the animals' demise.
US researchers said that in humans this could give rise to a heightened state of consciousness.
The research is published in the Proceedings of the National Academy of Sciences.
The lead author of the study, Dr Jimo Borjigin, of the University of Michigan, said: "A lot of people thought that the brain after clinical death was inactive or hypoactive, with less activity than the waking state, and we show that is definitely not the case.
"If anything, it is much more active during the dying process than even the waking state."