yellowted gave you excellent advice.

I would add to that:

1. Remove refined sugar / artificial colors / caffeine / processed foods from his diet.
2. Make sure that he gets 2 hours of play time outdoors every day.
3. No t.v. / computer before bed.
4. Allow your son as many safe and healthy choices as possible. Kids, just like adults, like to have some agency in their own lives and have some control over themselves.