The middle of the night holds no mystery for me. And in fact, I'm trying to remember the last time the night seemed long to me, even in winter.
No: usually if I go to bed early and wake up in the middle of the night--as I have tonight--it's to the realization that an alarm clock is going to go off soon (a handful of hours) and I'd better get back to sleep so I can heed it when it does.
Being beset with chronic anxiety, I have developed coping mechanisms. I've learned how to put things out of my mind--as many times as necessary--and try to think of other things. When you're laying awake in the middle of the night, plagued with self-doubt and (usually) baseless worry, it helps to be able to say, I am not thinking about this right now; it is fruitless to do so and think about something else. Even if you must do it fifty times before you fall asleep. I don't think I am possessed of unusual--or even very much at all--self-control.
But most of the time, when I wake up like this, it's because my body needs things done, and it won't wait until morning. Hit the can, get a snack and a drink--like that. Hydraulic pressure must be relieved; and although I once was able to, I can no longer sleep when my stomach is a yawning pit, at least not if I don't want to wake up with a headache. And then I'm up for around an hour, because I find it difficult just to eat something and go back to bed. This splits the night into smaller chunks, further reducing its apparent length.
That's what's happened tonight. And I, having finished my snack, feel my eyelids getting heavy again.
* * *
Which reminds me--
Been thinking about one of the worlds in my SF universe which has a 30-hour day. It's just six hours longer than Earth's is, and populated by humans, but they have lived there for a few hundred years shy of ten thousand Earth years. And I was trying to figure, with night being an average of 15 hours long, and with the day being six hours longer in total, how that would affect the circadian rhythm.
It used to be, apparently, that people would go to bed a short bit after supper, then get up late at night and be up to the wee hours, after which they'd go to bed for six or eight hours. I forget where I read that, but apparently that was a thing up until a century or two ago, before industrialization required that everyone heed a clock.
It occurred to me that this was probably what these people would do. I suppose it's possible for the human body to adapt to a 30-hour day, but it seems excessive: sleeping, say, ten hours, and then being awake for twenty. We know that those of us on Earth can't really do a schedule like that without all kinds of problems, not for very long. They live an average of ten times longer than the terrestrial variety of human, so theirs is a slow-moving culture, given to careful deliberation over hasty action, and it fits that they'd have something approximating siesta.
"...I'm trying to negotiate a treaty with these people, and suddenly someone declares it's nap time and they all go to bed!"
"Sir, they have a thirty hour day. I think that's to be expected. You know our own people have been having trouble with it."
"Maybe, but it's damned inconvenient, even so."
"Where are you going?"
"To my quarters! 'If you can't beat 'em, join 'em.'"
* * *
Sage advice. Off I go.