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 at the base of the spine to allow for a small pelvic tilt 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. If you have hip or sacro-iliac pain, place a pillow between your legs as well.
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.