A memory foam mattress topper is a pad made of visco elastic memory foam that goes on top of a mattress, placing an extra layer of cushion and comfort between a sleeper and his or her mattress. The extra cushion can make a firm mattress feel softer, and can give extra support to a mattress that is too soft.

Visco elastic memory foam is an open cell foam that conforms to the shape of the body, thus reducing pressure points while providing support. Originally developed by NASA, memory foam is temperature sensitive. When cold, a memory foam mattress topper is more firm. But the foam becomes more elastic at higher temperatures, such as when a person lies on the pad and the person’s body temperature warms it up. This is the effect that causes the foam to conform to unique shapes and curves of the body. When the person gets up, the foam gradually and gently returns to its original shape.

Several companies produce memory foam mattress toppers. The most well known is Tempur-Pedic, which was the first company to manufacture memory foam mattresses for the consumer market. Tempur-Pedic was not only the first, but is also one of the most expensive brands of visco elastic foam mattress products. Many other memory foam pads are available at various weights, sizes and prices.

The higher the density of the foam used, the firmer – and generally, more expensive – the memory foam mattress topper will be. Density is defined by how much one cubic foot of the foam would weigh. Densities run from two pounds up to five pounds. Lighter density foams are softer, but they tend to wear out faster over all. In addition, higher density memory foam takes longer to bounce back from its conformed shape. So, a sleeper who changes position frequently may prefer a lighter density mattress pad that changes its shape more quickly.

Memory foam mattress toppers also are sold in various thicknesses, from one inch up to as much as five inches. Thicker foam pads provide greater cushion than thinner ones. The desired thickness is a matter of personal preference, and can depend upon the weight of the people who will be regularly sleeping on the pads. Smaller individuals may be comfortable on a less expensive one or two inch pad, while those with more body weight may prefer a three inch or thicker foam topper.

Over all, the comfort, support and durability of your memory foam mattress topper will be determined by the combination of density and thickness. Visit a local bedding store or go online to see what’s available in your price range.