I've got decaff tea at home which (to a non-tea expert) tastes pretty much like the regular stuff which might be worth a try.
I dunno, it's probably not a one-size-fits-all situation/solution for sleeping patterns as stress, light levels in your room, diet and all kinds of stuff can affect it, apparently.
It's question close to my heart as my sleep's been pretty rubbish since I was very young but I do seem to have had a bit of a breakthrough recently. The BBC had a show on recently called 10 Things You Should Know About Sleep which was quite good. Looks like it's still on
iPlayer which might be worth a peruse.