Does anyone have any experience with a child taking sleeping medicine?

My six year old son has a pretty good case of ADHD. I was always pretty closed minded about medicating children until my son was nearly kicked out of preschool. His doctor put him on Vyvanse and the change in the boy is amazing. You would never know that he is either ADHD or medicated. He just seems like a regular kid-he didn’t seem like a regular kid before his meds.

One of the side effects of the the Vyvanse is that he has trouble getting to sleep. The doctor started him on Clonodine, one pill a night, but has since upped it to two pills a night, because my son would still be up for a couple hours after taking his pill. The two pills really aren’t doing much better. He took his pills at 730 tonight and was up watching Mythbusters when I got home from work at 1130. Does anyone have any experience with any of this? Is there something natural I could try instead of the Clonodine?