My son started having trouble sleeping at the age of 3. We did 5 mg Melatonin for quite a few years based on recommendation from the pediatrician, but switched to Clonidine 0.1 for the past few years based on his nurse practitioner that he sees for behavioral and developmental issues. It worked really well, but he is starting to have more trouble again. He is now 10. He also takes Concerta. Ask your Dr. about Clonidine and if she thinks it will help your son.