I'll echo Regretter's advice above about working out in the morning, not in the evening. The stimulation from a night run can stay with you for a while and interfere with sleep. Someone mentioned Valerian root which I use for sleep purposes and it's great! Like you, melatonin makes me groggy the next day, but I have no issues like that with Valerian. Your mileage will vary, of course. Other things to consider: a hot shower before bed, don't read or watch TV in bed - just go there to sleep (keeping it G-rated here guys), cut down on caffeine (I try not to drink any coffee or sodas after 12pm). And, yes, lots of exercise if you can. I find running to be a great benefit for all my addictive problems.
All of this helps me...