Do extra firm mattresses get softer over time?

They soften slightly as the comfort foam relaxes over the first few weeks, but this mattress is built to hold its firm feel. It uses 1.8-pound high-density foam, the densest in this Perfect Sleeper group, which resists body impressions better than a softer pour. Durability scores 6.9, Good, and most change happens at the surface, not in the 13.75-gauge steel coils. Rotating it head-to-foot keeps the softening even across the bed.