Can a mattress cause back pain?

Yes, a mattress can cause back pain when its firmness doesn't match your sleep position or when it has worn out and lost support, leaving your spine out of alignment overnight.

A mattress that is too soft lets the hips sink and bends the lower back, while one that is too firm pushes against the shoulders and hips. An old mattress that sags creates the same problem. Matching firmness to how you sleep, and replacing a worn mattress, removes the most common mattress-related cause.

Side sleepers generally prefer soft to medium mattresses for hip and shoulder pressure relief.
Back and stomach sleepers generally prefer medium to firm mattresses to keep the spine neutral.
Hybrid mattresses with zoned coil support under the lumbar region suit many back pain sufferers.
A sagging, worn-out mattress is a distinct cause of back pain from a wrong-firmness mattress.