Her check-in time is two in the morning for me and I am wrecked

We agreed a daily check-in at nine in the evening, which was reasonable when we agreed it because neither of us did the maths properly. Nine in the evening for her is two in the morning for me.

I have been doing it for five weeks. I set an alarm, I wake up, I message, I go back to sleep badly. It is starting to show at work and I have not said anything because I agreed to it and because on some level I quite like that it costs me something.

At what point is that a stupid reason to be tired all the time?