Any guesses as to why my hands hurt every night?

It starts late at night, as I’m falling asleep. In the morning, it’s really bad. No pain during the day.

I don’t do excessive writing/typing/etc. I don’t knead tons of dough. There’s nothing that I do differently, but this has only been a problem for the last month or so.

It’s both hands, and the pain feels like my muscles might be inflamed. Palms and fingers. It makes me want to flex them constantly, though that doesn’t really provide relief.