Hi A., I have a boy who was a non-sleeper too. Well, he's STILL noctural (almost 20 now), but he's the only of the three who had any sleeping issues. So, here's what I did:
I basically gave up. tehehe
When he was 3, I stopped trying to force him (like others have said, I too had 2 younger ones, plus, I'm not a good sleeper myself, you know?). He and his brother (20 months younger) shared a room.
I put the younger Quality Sleeper (yay!) to bed, waited til he was in a sound sleep, then brought the elder, NonSleeper (boo!) up.
I took him to the store, let him pick out a flashlight. And here was the rule, he was allowed to choose 3 books to look at quietly (and even THAT required policing, he'd drag it out, had to be a time limit on choosing books, too). There was no restriction on how LONG he could look at his books quietly with his flash light. Never needed it, turns out looking at books with his flashlight in his dark quiet room was enough to put him to sleep.
Turns out, he just doesn't seem to need the sleep the other two do. He's now a sophomore away at college and does manage to get himself up and to class on time anyway.
So that's what 'worked' for us. Maybe worth a try, right. As soon as the focused turned from YOU MUST SLEEP NOW, to the reading of books, his own secret little thing, that was the end of the overtired crazies!
:)