Do medium-firm mattresses like this one get softer over time?

They soften only slightly, and this tight-top resists it well, scoring 9.7 out of 10 for durability. Its comfort layer leads with natural latex, the most resilient foam made, which holds its shape far longer than memory foam. Below sit 1850 coils of thick 13.75-gauge tempered steel that barely sag. Rotating it head-to-foot occasionally keeps wear even, and the 10-year warranty covers sagging beyond tolerance.