Has always been a really good sleeper.
Lately not going to sleep for hours. No routine change.
Gets upset when he can't sleep.
Has promised no issues or problems he's not talking about.
Has drink, wee/pooh at bath time.
It is driving me nuts!
I think he's maybe just got in to a cycle of not being able to switch off and go to sleep, but how do we break it?
He'll have a night where he goes to bed and sleep normally and I think it's going to be ok, but then goes back to the can't sleep thing 

Any ideas/experience/advice?