Miss Puff (pictures to follow, maybe - it’s finals!) had fleas. I didn’t realize she had them until the biting/scratching got really obvious, and until I found one on me.
Before I realized she had a problem, I noticed that she had narrowed her places to sit - while she used to sleep on the bed, she was now only sleeping on the computer desk, right in my way. (Desk, box, bowl - nothing else.)
I put some Advantage on her a couple of days ago, and now she has been happily sleeping on the bed again for the last hour or so.
So it seems as though she was avoiding my sleeping space while she was infested, and is now ready to snuggle up again.
What a considerate kitty!