Don't take Xanax to sleep again. I know it's tempting, but it can cause real harm to your child.
I haven't had insomnia but cannot get back to sleep when I wake up to pee.
I try a few things that work... try to do something monotonous - I knit/crochet, watch a movie, or read a book.
You can also try some yoga - but light yoga, especially if you've never done it before. Yoga can really quiet your mind... you have to practice a bit before you get it right, but once you figure out how to focus on your breathing, it's amazing how calming it can be. Don't do anything that challenges your balance though.