Sleep on your back, on your stomach, on your side, in the fetal position with or without a pillow, on a soft or hard mattress? The way we sleep has direct consequences on our muscles, nerves and joints. Eventually, poor sleeping posture can cause back pain, especially in the lumbar region, but also in the cervical region. What positions should you absolutely avoid when sleeping? And the best ones for getting restful sleep? Advice from Charlène Chéron, chiropractor.