I'm with possum on checking with your doctor. I would not suggest filling a prescription you are no longer taking without speaking to your doctor first.

Another suggestion I can offer is to try to go to bed and get up at about the same time every day. Also pay attention to how much caffeine you are taking in during the day. Sometimes caffeine can be found in things like medications where you wouldn't expect it to be. I've heard to avoid caffeine for as many as 8 hours before going to bed.