I would try melitonin first because it is actually a chemical the body produces, so adding it will not interfere with other med's he may be taking. If it doesn't work, try other options based on doctors recommendations. I've read a lot of research about additional benefits melitonin provides. It's definitely is the safer first try. Hope it works!

My 10 yr old ds's therapist has him on Chlonidine 4x a day (1/2 pill 3x day, then a full pill at bedtime). It does seem to help w/his sleep, as he used to get up several times during the night, but now no longer does :)

We use a low dose melatonin every night with our 5 year old daughter with aspergers. It makes bedtime a much, much better situation. She never slept through the night until we started this about a year ago. All of her drs agree that it is safe, and she is in a much better mood after having slept all night. I buy it at trader joes. They have a 500mcg chewable.