I smoke hash, and I can't get my head around why sometimes I'm totally relaxed and other times the hash stimulates me to the point where I can't sleep and my mind starts racing with a myriad of thoughts and connections...not necessarily negative, although sometimes I'm given things to consider that affect my future. This is from the same hash, so it's not a case of different strains. I think, maybe, the hash just magnifies the subconscious minds. If we're relatively chill, we get nice and relaxed. If we have ongoing issues that lay just beneath the surface, they rear up and demand our attention with the aim of a resolve.