Ds is 11yo and is getting up some days at between 4-6am. Now he didn't have a clock in his bedroom which was a bit stupid of us really, so we got him a clock thinking that would resolve it.
He's still doing it. Now I'm a really deep sleeper, I get up at 6.30am for work and sometimes ds is still in bed or so I think, but dh is a light sleeper and gets up earlier, and tells me that he's found ds getting up at all hours and has sent him back to bed, so when I think he's sleeping he's actually wide awake. Other days dh might have to be up at half 5 and gets up to find ds sitting downstairs.
I've told ds to stay in bed until at least 6.30am and try to go back to sleep but he's obviously ignoring me.
He goes to bed between 9-10pm.