Sometimes I wind up on a sleep schedule that I dislike -- say, waking in the late afternoon and going to bed in the mid-morning.
Those times, I'll often "force normalize" my sleep -- meaning, I'll stay awake for many hours in a row, and then sleep a lot. So if I've been waking at 1PM and sleeping at 5AM and want my schedule to be earlier quickly, I'll sometimes just skip a night of sleep.
5AM will roll around, I'll have been awake 16 hours, and then I'll stay up another 12 hours -- to 5PM -- and go to bed.
I'll usually wake up the next day sometime between 4AM and 7AM, and then -- good.
If you've been skimming and reading fast, the basic idea is that if my sleep schedule is screwed up, I'll sometimes stay away sometime like 24 to 30 hours, and then sleep 11 to 14 hours, and then be back to normal.