By making simple changes in your sleeping position, you can take strain off your back. If you sleep on your side, draw your legs up slightly toward your chest and put a pillow between your legs. Use a full-length body pillow if you prefer.
If you sleep on your back, place a pillow under your knees to help maintain the normal curve of your lower back. You might try a small, rolled towel under the small of your back for additional support. Support your neck with a pillow.
Sleeping on your stomach can be hard on your back. If you can't sleep any other way, reduce the strain on your back by placing a pillow under your pelvis and lower abdomen. Use a pillow under your head if it doesn't place too much strain on your back. If it does cause strain, try sleeping without a pillow under your head.