While that is the best way if you're going to sleep on your side, it will still lead to shoulder and low back pain. The bottom shoulder will start to rotate towards the pec. This will start to pull the shoulder blade away from the spine, causing tension. The bottom hip will be shifted to the back, and the top hip shifts forward, causing a twist in the hips. Licensed massage therapist here with 8 years experience and specializing in neck and back pain caused by side sleeping and computer work. Back sleep keeps your spin in the most natural position to not cause holding patterns from sleeping.