Well, since I mostly ignore mystical stuff since they can't be proven...
Scientifically speaking, OBE sounds like a Lucid Dream to me that can be hampered by subconscious thoughts about you know, OBEs.
As in, you believe it subconsciously that you'll see a silver string connecting you to your body and that you'll be in your astral form or whatever, but it's actually a dream that's you don't have complete control because you don't really believe it to be a dream, but to be an OBE.
Does anyone else have similar thoughts? I really don't believe in mystical stuff though, so sorry for OBE supporters, I'm not trying to offend you