It is common for kids on stimulants to have trouble falling asleep at night - my 11 yr old son did until we switched to Tenex which is not a stimulant. At any rate, this is what helped my son:
- same routine every night is important - he will find this comforting
- 30-60 mins before lights out we get him a drink milk and give him 1 mg of melatonin - our pediatrician said it is safe.
- we read to him or had him read to himself in bed
- before turning lights out we put on CD of calming classical music.
By the end of the CD, he would be asleep most nights. There are times he still has a hard time falling asleep and it is usually before something big like xmas, halloween, birthday or testing at school. Sometimes it would be because he was stressed out/ having trouble at school, etc. So it helps to talk a lot and try to pinpoint what is going on. I also find that if I keep him active he sleeps better - swimming, taekwondo, baseball, etc.
I hope this is somewhat helpful - Good luck!
M.