I used to take a more scientific viewpoint as you articulated, but I must say that over the years I think much of what we are goes beyond the science of the matter. You could also say that love is nothing more than a chemical reaction, or that a "faith" gene has been found in humans. In a similar way, dreams can be considered chemically induced hallucinations. But I am now thinking they transcend and are more than the sum of the chemical reactions involved. There is an "other dimensional" aspect that one clearly experiences that is hard to satisfactorily explain.