Yeah, you're probably right about being too mentally awake. The key is to be able to let yourself drift off, while keeping little alertness.

I think what would help you is to get yourself really tired before bed and try it, usually it works with me because I tend to have a pretty active brain attempting WILD as well. Being tired will stop you from being too awake, and your body is pretty much trying to get it's rest, so the process should come quickly.

Hope this helps
          Current LD goal(s): Visit: Imladris, Lothl贸rien, Hobbiton.