My robos get up at 3am and stay up until 7am, my Syrian is 10pm until late my others just get up randomly in the day and night its typical hamster behaviour and nothing to worry about
I enjoy the fact they all get up at different times though, it makes handling and play time easier. Hams are crepuscular meaning that they are most active in the twilight hours and not so much in the day light (dwarfs seem to be the exception) it's one of the reasons why they don't make good 'kids pets'
Ps Custard, I just noticed you live literally up the road from me!