i’ve never had much sleep trouble, but i started mysteriously waking up at 4:40-4:45 am every night for a week now

You're waking up in sync with me bby. It's a sign of our bond 👉👈

Same thing happened to me but it's going to be a year now. 3, 4 or 5 AM. I didn't used to have this problem before. Now it's rare when I sleep through the entire night.

It's because you are missing me and haven't realized it yet 😎

Seriously though, it could be anything from a shift in your mental state to it being time for a new mattress. Sleep stuff is weird and so much impacts it.