Depends whether I'm working or not. If I'm at work the next day I try to get to sleep at around ten, to get up at six the following morning. And because I work either two or three days in a row before my next block of days off (shift work) I will try to get an early night that night too. To be honest, that's not hard, since I work twelve hour shifts and I'm pretty damn tired when I get home.
If I'm not working the next day, I usually get to sleep anywhere between ten at night and one in the morning, and will probably wake up somewhere between six and eight. I've never been able to lie in. Even during school holidays and stuff, I'd always be up horribly early in the morning, when everyone else I knew was able to use the holidays for mega-lie-ins. The only real advantage is that it allows me to maintain a fairly regular sleep cycle.