[[Memory foam]] mattresses use conforming visco-elastic foam over firmer polyurethane base foam. Some innerspring mattresses have memory foam in their upholstery layer. Different feels and comfort levels are achieved by varying the thickness, weight and formulation of the visco-elastic foams and the base foams. Latex and memory foam mattresses each provide a unique feel. This type of mattress is good at relieving pressure on painful joints. Many memory foam mattresses are more expensive than standard spring mattresses.

Memory foam is affected by temperature. In a cool bedroom, a memory foam mattress will feel firmer than it does in a warm bedroom. Memory softens and conforms to the sleeper in response to body temperature and body weight. Traditional memory foam molds to the body creating a depression the sleeper must roll out of when changing sleep positions. Mattress manufacturers have responded to this issue by using "faster response" memory foams. They spring back more quickly when the sleeper moves. Foam mattresses are also known to generally "sleep warmer" than innerspring mattresses. Mattress makers have addressed the issue with "open-cell" memory foams, pinhole cored memory foam, gel-infused memory foams, channel-cut foam cores, reticulated foam support layers and other technologies to improve air circulation through all-foam beds.

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