I also believe that as humans, although we operate on a 24-hour cycle, biologically we exist on a 48-hour cycle.
That means if I have a late night on Saturday, I will feel worse on Monday, because the cumulative effect of lack of sleep that night will impact on the Sunday night, making the overall sleep shorter, and me feel bad two days later.
Similarly, if I want to stay up late on Saturday, I will go to bed early on Thursday, to get ahead of the sleep I will need not to feel like death on Monday.
That said, I suffer from serious sleep aponea, and I can literally sleep anywhere at any time, and I mean anywhere - I can sleep in a toilet cubicle!
Try it - there is nothing comfortable to lean on, and your feet will slip if you try and brace yourself to stay on the seat.
For me, I simply lean forward, let my head drop, and I'm gone. It takes a little concentration but I can be asleep in less than sixty seconds, less if the area is comfortable, like sitting in a car, or obviously in a chair.