If you’ve spent any time mattress shopping, you’ve probably run into the same wall of confusion we did: every brand claims theirs is “the best,” but almost nobody explains why the materials actually matter for your sleep, your body, or your health. Let’s clear that up. What “Memory Foam” Actually Is Memory foam is a petroleum-based polyurethane foam engineered to respond to heat and pressure. It was originally developed by NASA in the 1960s to cushion astronauts during liftof