Memory Foam

Memory foam is a viscoelastic polyurethane foam, meaning it answers heat and pressure by giving way slowly and returning slowly. Press a hand into it and the print stays for a few seconds. A memory foam mattress uses that material as the comfort layer over a firmer high-density foam base, with no springs anywhere in the build.

Slow response is the whole character. The foam moves only where it is loaded. Movement on one side of the bed reaches the other side almost not at all. That is the main reason for it in a shared bed. The same behavior spreads your weight across a broader area, relieving pressure at the shoulder and hip.

Density is the number that predicts life. Comfort foam at 4 pounds per cubic foot or more holds its shape for years. Foam at 3 pounds and under softens and dips early, and it is where cheap boxed beds cut cost. Since the whole mattress is foam it compresses for shipping, which is why boxed mattresses are nearly all built this way. Allow 24 to 72 hours for a new one to expand fully and air out.

Heat is the standing complaint. Foam surrounds more of your body than coils do and the material itself softens as it warms. The bed can feel different at 3 in the morning than at bedtime. Gel beads, copper and open-cell structures reduce that without curing it. Deep contour also slows position changes, which restless sleepers notice within a week.