No, science DOES know of these things. They have been reported upon and studied. The phenomena exist, scientifically. The CAUSES are also generally known to science, and there a sound physiological explanations for them. They are, as far as can be determined, inner processes of the brain and not OBE's.
Yes, they have been studied some. I have managed to dig out the program I was talking about, in which several scientists talked about near or death experiences.
More of that later. My own conclusion is that the jury is still out on that one.