I have been ADHD all my life, 35 now, and sleep has been extremeley difficult for me since infancy, so my mom says. I cannot recall any long stretches of time when I have been able to go to sleep quickly. Yes, I agree that carbs and sugars should be eliminated later in the day. Makes a huge difference for me.
My son is 7 and ADHD. He sleeps very well, and has since birth. However, if allowed, he will stay up forver. He is on Metadate CD and is ready to snooze by 8 at the latest, but bedtime is 7:30, so reading works.