School Days- 11PM-1AM Maybe later, depending on how much work I have and how tired I am.
Weekends- 1AM- Morning Depending on what I am doing, who I am hanging around with, what I am smoking :P, etc
Vacation/Break- Whenever I want. Sometimes I get really tired, really early.
When I'm tired- Refer to the first two.
When I'm sleeping over a friends house- If I'm sleeping over, it usually means that we are going somewhere.(snowboarding trip, beach house, etc), so I go to bed early.
Naps- Whenever I want to. Time/Situation permitting of course.