"but if you are worried the return back to sleep (& therefore risk him being awake from 5am)"
sorry, what do you mean by this?
Ok, lately he has been letting out a little cry at 5.30am & going back off to sleep, or sometimes he will continue to cry, I can go in & settle him & he will go back off. But he will only usually go back to sleep until 6-6.15am. But during this 45mins, he is usually on & off grizzling, not in a deep sleep. Then finally at 6-6.15am he will be standing & crying and wanting to get out of the cot. But he doesn't look fresh and happy, his eyes look sleepy, so yes, I think you are right, he may be overtired.
I am trying to overcome the overtiredness at the moment- with early bedtimes.
Jx