Back sleeping and sex dreams

Enndea

This is what has been on my mind lately.  First off, I am a back sleeper naturally.  I got one of those "snoogle" pillows and it's comfortable, and I start on my side, but always end up in the night rolling back on to my back.  When should I start to worry about this?  Does mother nature ever kick in and let you know "hey, you're on your back and that hurts" or is it just something you have to be vigilant about?  Any of you have any tricks to prevent you from rolling?  

Secondly--I think pregnancy has hijacked my hormones.  I am having sex dreams EVERY night.  And I wake up feeling like a nocturnal philanderer since in the last week I seem to have had dream sex with every ex I have ever had.  What's up with that??  Makes me feel HORRIBLE!