Hi,
Stimulants can often interfere with sleep, but there are some things you can do to help your son. First, as I'm not a physician, it's imperative to discuss your concerns with his doctor. It's possible that he's taking his medication too late in the day. Or that the dose is too high.
Lots of youngsters your son's age have poor sleep hygiene. They may be on the computer too late at night, or playing video games, etc. See if he's willing to find calming activities, like reading or relaxing to soothing music.
Also, even kids with ADHD who are not taking stimulants often find it hard to fall asleep. That's often because their brains are in hyperactive mode. The trick again, is to find calming, boring activities so that he can shut down. Some kids (and adults) find themselves ruminating over the days' events. If that's the case with your son, you might suggest that he keep a notebook by his bed and "dump" his thoughts, worries and concerns on paper so he can free his mind up.
Warm baths, warm milk actually also help.
However, if all your efforts still don't help, it's really time to discuss this problem with his doctor.
We have a number of articles and Share Posts on ADHD and sleep at http://search.healthcentral.com/query?q=sleep&st=s&ver=adhd
Terry