My son also had an extremely hard time going to sleep. I found out these kids have very over stimulated brains. That is why spankings don't work.
Physical pain overloads an already overloaded brain.
We spent a good part of every evening with a long long play bath, storytime, etc. We figured we couldn't concentrate on anything else anyway, so we might as well work on downloading his hyper brain that got so wound up during the day. But it wasn't till we put him on medication at the age of ten that life became not only bearable, but downright pleasant. For the life of me I do not understand why it is ok to take insulin if you are diabetic, synthroid if you have a shortage of thyroid hormone, estrogen for menopause, etc. Actually, statistics show the medications for ADHD are safe and non-addicting when given under a doctor's care.