Insomnia is one of my curses, with or without Xenical, but odd as it may be I seem to have been getter better with it since being on it, go figure! I think it is because I have been worrying about my obesity and feel better for doing something positive about it the other tip I would give is:
Save some calories for a nice pre-bed snack and do something relaxing before going to bed. I normally get into my night rags and play on the Pooter for a while, catching up with the forums then having a game of Solitaire or something whilst having a nice low cal Sandwich, then off to bed, it is working for me.