Comment by 0xEF

Your back hurting could be a number of factors, but the big two would be your mattress or your posture/overall while awake. Try doing planks and crunches each day to build up core strength, which makes it a bit easier to maintain good posture, though that still takes considerable corrective practice. I have two back injuries, so all sleeping positions suck in different ways for me, but doing daily core exercises helps take the load off my back while awake so it hurts less at night.