I know of two studies that were and are being carried out, one in Holland and one in NHS hospitals in England. I am sure there are others. I will try to find these again and add the links. I remember that the one in England concluded that there was no scientific explanation (given current scientific knowledge) to explain the observations. I am fairly sure this was also the case in the Dutch study.
In the UK study researchers concluded a new quantum science would need to be invented or words to that effect to explain it. One of the mysteries was the fact that not everybody they studied had an NDE. According to their hypothesis, if NDE's were the result of a biological mechanism that occured as the body closed down, then everyone would have the same experience.
I have also read numerous articles by so called experts claiming that since similar effects can be duplicated on a living person by closing down certain parts of the brain in living subjects that this indicated that NDEs were a fallacy. However, might not this prove the opposite? Might it not indicate that the conscious/subconscious is capable of observing the body from a different dimension i.e. from outside itself. By closing off a part of the brain temporarily they may have unwittingly triggered the body into believing it is no longer a biological entity thus releasing it's energy/soul into another level of consciousness. Those carrying out these experiments do not appear to have considered this possibility at all.
Scientists like all experts in any field have a tendancy to try to box their findings into the confines of their discipline and training. They observe, measure and conclude within the parameters of their understanding.
I saw a documentary recently on BBC on the Seven Ages of Stars. In it they explained the formatiom (birth) evolution and death of a star. Its born, ages and dies. This is certainly what appears to happen but it is only part of the process. They did not ask themselves where the star came from or where it went when it died. The story is not nearly as clear cut as the program makers would have us believe. There are an infinite number of ages to stars. What is a star? It is simply energy in motion. When the star collapses and disappears from sight, the energy that momentarily appeared as a star came from a previous state of energy before transforming into yet another state of energy after its collapse. It did not suddenly appear from nowhere nor does it suddenly vanish into nothing. It remains part of the energy that makes up the totality of the universe from which new stars or energy forms are generated.
Science is obsessed with a beginning and end scenario to everything. Thus in the eyes of science everything that is born also dies but in reality there is no beginning nor end to anything. All there is, is energy in some quantum form and it must be eternal and indestructible. How do we know that? Its simple logic. Since nothing can emerge from a state of nothing and since something (universe) exists, a state of nothingness cannot exist. The only thing that seperates everything from nothing must therefore be eternal energy in manifest forms from which everything that is, emerges and evolves.
Thus, following this simple logic, the true nature of everything is really nothing more or less than varying infinite states of energy resonating at infinite levels of frequency. As stars evolve the energy resonates at varying frequencies. The same must therefore be true of the energy which gives rise to us. The frequency at which we resonate at any given time in our lives transforms us from what we were to what we are and what we will become. We change but like the stars we are a manifestation of energy in transformative motion, without beginning and without end.