I’ll usually put my hand on her belly or the top of her head, just to let her know that I’m there.
If they are in their dream sleep softly yipping or even softly grrr-ing... is it good to wake up your dog?
Most internet sites advise against it, but I like the common sense advice on this one---
https://www.petful.com/behaviors/my-rescue-dog-has-nightmares/