When should I just give up for the night?

At least once a week I'll have a night where I just can't sleep for literally no reason whatsoever. I have a decent sleep hygiene and stick to it even over the weekend, I do the whole "try to sleep for around 20 minutes and then get up to do something for half an hour" shtick even though it doesn't do anything, I toss and turn and break down at some point because I have exams, appointments and whatnot that I just can't miss, but even on days where nothing is going on I just break down at some point.

I had weeks with barely any sleep not too long ago so I'm already immensely glad that got better, but that one night a week is just horrible and I'm dreading it whenever I can feel it come on, especially since often the night after is fine again because I literally pass out and then the next day is at risk of being the same thing over and over again. There's times where this one day a week has evolved into four days a week because every second night I just can't sleep at all and I just can't handle it anymore with having to function like most other people and them looking at me, asking why one bad night would be such a big deal.

It just makes it worse to stay awake and trying to sleep because at some point I panic, I get so frustrated not being able to sleep that I just start crying even if I could still get 3 to 4 hours or so. But even if I try after that, being all exhausted, I just can't do it.

When do you just stop trying for the night? I just want to save myself the frustration of nothing working. Maybe it'd be better to just start the day earlier than usual or something...