My son has ADHD and has never been able to sleep without help. The doctor gave him Clonidine to help him sleep. I don't recommend it. He ended up having a seizure because the medication lowers your blood pressure. We have found that a low dose of Melatonin (3-5 mg) works like magic. Melatonin is something that your body naturally produces. People with ADHD don't have enough of it for some reason. You don't have to worry about being "drugged up" on it, and if you truly don't need it, it won't help. ADHD medications also keep children from being able to sleep. Hope this helps. I know it can be a miserable time until you find what works for you. Good luck and God bless.
I think you need to seek a second opinion. I have heard that ADHD alone can make people have brains that "wont turn off." I myself can't do that either-- I have to distract myself to sleep by keeping the TV on or reading until I fall asleep.