I suffer with this.
I’ve found that keeping a notebook or a notebook app on the phone nearby to scribble down things I remember in the night, or as I’m dropping off allows me to clear my mind and stop worrying.
Wife used to have this, only thing that sorted her out was an audiobook on her ipod. The more boring is was the better.
+1 on this. I’ve got The Universe in a Nutshell on mine 🙂 I actually find it very interesting, but the chap who reads it has such a relaxing voice, I can’t help but drift off after a few mins.
It also has the added bonus of being able to randomly spout off snippets of info about telescopes which see back to the big bang, quantum oddities which occur on the horizons of black holes and the General Theory of Relativity 🙂