Caffiene does affect people with ADD differently. Stimulant meds actually slow our minds down, making it easier to think. It sounds weird, but the longer I go after my last Adderall, the harder it is for me to go to sleep. As the meds wear off, my brain starts spinning again. Another key to sleep for me is getting in some exercise. On the days that I get my morning and evening walks in, I have a much easier time sleeping.