Science offers some explanations that make some sense yet they are rather limited
According to some scientific viewpoints Near Death Experiences may be produced by a number of factors.
Studies in the laboratory have shown that lack of oxygen can create Memory Alterations, Visual Distortions & Tunnel Vision
It is believed by some scientific researchers that drugs (either medicinal or produced by the body) may be responsible in producing Near Death Experiences and that these experiences are nothing more than hallucinations.
Many scientists believe that our fear of death is so great that our brain creates a self-preservation fantasy when approaching death. An individual detaches from a sense of self in order to avoid emotional pain or stress.