Hey Jane. Sorry to hear you're having to deal with that - I've been going through the same thing the past few days and I know how frustrating and difficult it can be. You can deal with body memories just as you do flashbacks. What Nyx posted above is a good way to ground yourself. Here are a couple other suggestions:
Try focusing on your breathing: One exercise that helps me is to take a deep breath in through your nose, and out through your mouth slowly. Count to 3 inhaling, and count to 3 exhaling.
I also find that playing some music while I try to fall asleep helps keep me distracted. If you like music and can play it while you sleep, try to put together some songs that soothe you and do your best to keep your focus on the songs.
And one important thing my therapist told me to do (not that I've done it yet lol!) is to get up and ground yourself if you are having body memories. Instead of sitting there with those feelings, try to get up, turn on a light, and do something relaxing for a little bit before you try to sleep again.
I know that these can be a lot easier said than done, and they may not work all the time. Keep trying and you'll figure out what works best for you. :) I'm really glad to hear you'll be starting therapy next week. Good luck! Let us know how things go. Hope things start to get better for you. Hang in there <3