I believe memory foam mattress is starting gaining market shares in the industry due to its ability to mold itself to the sleeper's body. The memory foam inside makes the pressure from mattress spread over a greater of portion of your body; as a result, it is better for your shoulders and hips. This type of mattress will remember "the shape of your body."

Memory foam mattress is made from polyurethane (PU) and is composed of billions of air-filled cells. When you lay on memory foam mattress, it adds pressure to these cells and they will decompress under the pressure. Then what we will happen is that the foam slowly release the air and create a melting effect, which allows the mattress conform to the shape of your body.

Since almost all of the memory foam mattresses will do pretty much the same and has the same functionality, how they differ in quality and price? Well, most memory foams defer in density and depth. Density generally determines how you feel on the mattress when you lay down and it affects the durability of the mattress. In mattresses, the density commonly ranges from 2 to 6 lbs/ft3. As a shopper, what you need to remember is that higher-density memory foams generally last longer and thus will cost more than the low-density ones. Other than the top layer, most mattresses have a bottom layer as well. The thicker the layer of memory foam, the deeper your body will sink into the mattress. This is not a matter of quality of the mattress but a matter of personal preference. Higher-end manufacturers tend to use a thicker top layer (e.g., 3-4 inches or more) of high-density memory foam because this combination ensures that the greater firmness of the high-density memory foam is offset by the greater depth of the memory foam layer.

Located in UK? You can learn more information about mattress and shop mattresses at UK from
Simply Sleep - Memory foam mattress manufacturer based in the UK. Full range of mattress sizes available, order memory foam or pocket sprung mattresses online with next working day delivery.

Here is another site where you can find a collection of furniture stores:
Furniture Store Directory - Offers directory of furniture links through the furniture industry.