What you sleep on can also affect how comfortably you sleep. If adjusting your sleeping position doesn't help reduce back pain, try adjusting your sleeping surface. Mattress firmness is an individual choice. If you have chronic low back pain, you may benefit from sleeping on a medium-firm mattress. Consider trying out a medium-firm mattress before you buy. However, you may find your back pain is reduced with a softer mattress.
If you have bursitis in your hips, you may find that a foam mattress pad reduces pain. And sleeping in an adjustable bed or reclining chair that keeps your head and knees up may help with low back pain.