A question that often comes up with my clients who have back issues is what position should they sleep in. If that's a question you've asked yourself too the simple answer is that there is no definitive answer.
This is according to Dr. Stuart McGill a well-known expert on back pain. His guiding principle is this: avoid what hurts you.
Esther Gokhale who developed The Gokhale Method recommends a similar approach with some interesting adaptations that my clients have found extremely helpful.
Here are some of their recommendations:
Stomach Sleepers: If you have pain intolerance with flexion (rounding of the spine) for example, you may do well on your stomach. However, this would be impossible for many older arthritic spines.
Back Sleepers: If you like to sleep on your back but you wake up in pain is your back flattening and flexing (sagging) into the mattress?
If so try placing a small folded blanket under your low back to prevent the spine from flexing. Or roll up a small towel and place it across your back at the base of the spine (at the L5-S1 segment where the buttocks meet the low back) to allow for a small anterior pelvic tilt, opposite to tucking your pelvis under and to prevent a flat back.
Place a roll under the knees as well. If you have hip pain, a pillow under the knees is helpful, while for some individuals this only aggravates the pain.
Side or Fetal Position: If you like to sleep on your side in a fetal position but this triggers back pain, try bringing your spine into a more neutral or straight position and lay right on top of the bottom arm on the shoulder. If you have hip or sacro-iliac pain, place a pillow between your legs to reduce the strain or pull on the sacro-iliac joint.
More Resources: Video: What is the Best Sleeping Position by the St. John-Clark Pain Treatment Centre, Neuro-Somatic Therapist . This is an excellent video and demonstrations of the different adjustments you can make to sleep more comfortably.
Article for various body conditions like acid reflux and leg swelling: Sleepy Science:Is There a Best Position to Sleep In? by Christopher Labos, MD, MSc.