I am a fan of the Dr. Oz shows where he deals with many people's health issues.  On a recent segment, he addressed sleeping positions and different ways to sleep better.  I was hoping he'd talk about beds, but he didn't.   He spoke of the correct height pillow  for each sleep position(flatter for stomach sleepers, medium for back and fluffier for side), and recommended a pillow for between the knees to keep the pelvis aligned.  All this I had heard before.  What I had not heard before was his recommendation to use a small rolled up or folded towel(I used a quilted piece of fabric folded to about 4" wide) under the low back for back sleepers(and I think side sleepers) to support the low back.  Hmmnn... 
I did notice that when I am on my side that I tend to let my upper hip lean over toward my waist, which leads to tightened muscles in my low back.  I realized that this happens because there is a void under my waist area, and when I kept my waist  up off the bed my hips stayed aligned. So last night I tried it.  What I found out was pretty cool.  I never woke up during the night, slept straight through!  Very unusual for me.  The folded up quilting stayed in one place the whole night, and I rotated from back to sides.  My back felt very strong and relaxed when I woke up this morning.  I did feel a tinge of discomfort where the quilt was up under my low ribcage, but not much.  This was a really great tip and I recommend others try it. 
Kait