I don't know about your particular situation but what has helped me to sleep better has been to set a schedule and stick to it.
I get up at about the same time everyday, 7 - 8 am, I eat regular meals at regular times, especially dinner, eating right before bed will make it harder to get a decent nights sleep; it can also make you gain weight in case you need extra incentive :), also no caffeine in the evenings. Then get to bed at a decent time even if you aren't particularly tired, its easy to start going to bed later and later and before you know it you aren't going to bed at all.
Besides that try exercising in the afternoon, you don't burn off much energy sitting in front of a computer all day, its amazing how much it will wear you out just to go out for a few hours, or take a walk around the block.
Its also important to deal take some time to relax during the day, don't save your worrying for right before bed, make bedtime a time to just relax, when you get into bed let everything go until tomorrow, this takes some practice but no matter how bad a day I have I try to get into bed and just breath for a while and then I drift off.

Making and KEEPING a schedule should help you with your insomnia and should help you to be less stressed in general.