Sleep is very important, and 'scheduling' it at (approximately) the same time each day is definitely best (because sleeping at irregular times is unnecessarily stressful for the body).
At what time you go to bed is not very important though. Your body doesn't 'know' in which time zone you are and what time it is. There's no difference between going to bed each day at 22.00 and getting up at 6.00, and going to bed at 1.00 and getting up at 9.00.
However, a related factor you may want to take into account is that it is supposedly best to be woken up by the natural sunrise. In a darkened room, a machine like a philips wake-up light can mimic that effect at a time that suits your daily schedule. I am not sure though how beneficial this is healthwise.. It would be interesting to hear what HV has to say about this. :-)