How do you sleep?

I was "diagnosed" a few weeks ago with SPD. Well, I am finding myself waking up from sleeping on my back...Or it's the only comfortable position I can lay in to fall sleep. I know you're not supposed to sleep on your back! But, what can happen if you are? I do roll over and usually go right back to sleep, it's not really that my sides are uncomfortable to sleep on...I dunno maybe I am just worrying myself.