It depends what shift I have at work the next day. 9:30pm if I have to open shop, 10-11pm if I get a later start.
When I don't have to work it's usually around 10:30 or 11:00pm. Rarely after midnight, I like to get up reasonably early to enjoy my days off. And I need AT LEAST 9 hours of sleep to feel good.

Oh, and I can't sleep without a hot shower just before bed