When the difficult children were young (up until the age of about 13 respectively for each) I was able to maintain a very strict bedtime for each of them. I think you can find threads bout it here. It started at 7 and as they got toward the older age it went to 8 and that was really early for older ones but I found that's the magic time that they needed to be in bed by. Once magic 13 hit then I've had a heck of a time getting them to adhere to that time no matter what, even with medications that are suppose to aide them in sleeping. Middle difficult child is about the only one that really sleeps early at times on her own but she has always been my one that LIKES to sleep (ok older one does too but that is her depression and she will sleep all day now that she is adult because she will stay up all night).
Interesting in that all 3 also have to have music and at the barest minimum white noise but mostly music. In fact mr busy has a cd of Enya that has a single song that he listened to, I kid you not, for 7 years straight on repeat through out the night. We, as a family, are so sick of hearing the same song all night long for 7 years as he won't listen to it at a reasonable level and it has some pretty heavy drum beats to it. I don't know how he can put up with it and have long tried to figure out what it is about that particular song that he finds soothing. For a while I even started to wonder if it had some kind of subliminal message to it because he would freak out if he could not listen to it and would not sleep without it, PERIOD! There are words but it's nonsense words/language.