Sleep is I believe 16-18hrs "tired" and 24hrs "Tired (exhausted)/level 2" (its one or the other, not a range between 16-18hrs) if you go to sleep at 10pm, you will get tired around 9ish or so, give or take the difference in change from what was past the hour.
If you go to sleep at 5 in the morning, you will wake up likely in the later hours of the afternoon, and not get tired again for that "tired" frame of time, and you can't go to sleep till tired or exhausted, soyou will essentially be off schedule for days, until you slowly reset the schedule, or be tired for a very long time (exhausted/level 2) until you can sleep at the proper time to keep schedule.
I personally find it best to sleep between 10 and 11pm if at all possible, to keep the most store hours available, if I'm "bored/done" with a particular day, and tired too early, I'll wait around messing with stuff until its between 10 and 12, if possilbe, if its already well past 12, I don't bother sleeping.