"They'll think I don't care if I sleep"

The fear under the old rule, for a lot of people, is about the other person. If you say "let's stop", they'll hear "I don't care enough to finish this". The staying up is the proof that it matters.

Consider what caring looks like at eleven. It looks like a person who's tired, saying the same thing for the fourth time, with more edge, to a person who's stopped hearing it. It looks like the sentence about their mother at half past twelve, which came from the late brain and not from care. Staying up doesn't show that the row matters. It shows that the old rule matters, and the row is the thing that suffers for it.

There's a sentence that says what you mean, and it's the one chapter 20 is built round. "I care about this too much to do it tired." That's the truth. The row matters enough that it deserves the version of you that can think, and that version isn't available at eleven, and saying so is the opposite of not caring. It's taking the thing seriously enough to protect it from the hour.

The other person may not hear it that way the first time. If the old rule has run in your house for years, "let's stop" has always meant "I'm done", and it'll take a few weeks of resume times kept before it means what you mean. That's chapter 17. The way to make the sentence believable is to be at the table at eight, and to be there every time, and after a month of that, "eight o'clock" said at half past ten is heard as a promise and not as an exit.

And notice what the other person is actually asking for at eleven. Not the settlement. To be heard. A truce called properly, with "I've heard what you're saying and I want to answer it properly, and I can't at this hour", gives them that, and the settlement at one never did, because by one nobody was hearing anything.