The latest research I've heard somehow differed
So, there is several components that charactize a NDE and temptative scientific explanations sum it up like this
30 seconds after cardiac arrest, a peak of electrical activity would occur before the cerebral death, which could potentially explain the "life review event" and "tunnel with light".
Despite a flat EEG, neurons are initially still alive and release neurotransmitters massively, leading to a residual activity In other words, after several minutes past the last breath, neurons get activated again, release energy and blossom into a tsunami in slow motion of images and memories
Out of body experiences could correspond to the stimulation of a very specific part of the brain and happen in other situations to jetplane pilots, high mountain climbers, during high fever, meditation or trans, an orgasm, with Ketamine / DMT, etc
The corpse apparently releases opiods when it suffers a lot nearing the end, explaining the high sensations of joy and peace
It was also demonstrated that the interpretation is dependent on the culture, exposure to religion or spirituality and in this way varies around the globe
All of it, these processes would be part of a program attempting to delay the death and make it enjoyable (hormons also at play) ...although the mindset and context could influence the outcome how a NDE is felt, either good or bad (10%-20%). Some studies measured that suicidal people would experience more nightmarish NDEs (other times, this criteria was irreleant)
That's for the naturalist approach.
More and more smart people and physicians included nourrish a belief in semi-spoken words that our reality (3D & time) is a production of an everlasting consciousness captured by the brain acting merely as an antenna. Once dead, it'd survive in other realms (8D)
This could tend to go hand in hand with other studies revealing those with mental illness report less or no NDEs (i.e. their antenna would be supposedly damaged)