These medicines seem to make me even more tired - which is strange considering the amphetamine based ones are supposed to do the opposite.

The statement above I took out of your post, is the answer in itself. Your thought process on how an amphetamine based medicine should work, is based on how it effects a normal brain. In the adhd brain it actually has the opposite effect. It stimulates the award center in the brain while also relaxing you due to the dopamine and feel good chemicals being released. So it actually has the opposite effect then what you think it would. When I first started taking adderall I would actually sleep better if the dose carried over into when I was going to sleep. I would fall asleep faster and get a more restful sleep it seemed But I think my body has adjusted and that effect is not as prevalent.

Another example of a drug that has the opposite effect then what you would think in the adhd brain is cocaine. In a normal person it makes them stay up for hours and keep going for days on end. But for someone with adhd it actually can do the opposite and clear there head and allow them to function normally. From what i have read often times people who have adhd are addicted to cocaine not for its energizer bunny properties, more for the clearing and calming effect it has on the adhd individual. I think it was discovered that 70% of people who use cocaine had adhd. Don't quote me on that I would have to find the article in my books but the percent was high because they were able to be a more effective person while the cocaine was active. Clear thinking/headed.