Memory foam/visco elastic 

What is it?

Memory foam is the common term for visco-elastic polyurethane foam, a product developed by NASA in the 1970s. Memory foam is sensitive to both pressure and heat; different versions of the foam possess these characteristics to varying degrees. Memory foam enthusiasts often say that the mattress is both soft and supportive at the same time. 

Relative Popularity

Since the early 1990's memory foam has become a popular mattress and mattress topper material, and is currently the fastest growing segment of the mattress market. 

Most Popular Brands

Tempur-Pedic, Sleep Innovation Foam Mattress, Sealy Memory Foam Mattress 

Negatives

Many companies are now manufacturing memory foam mattresses and toppers, and product quality is highly variable. Try to find a reputable manufacturer and avoid the lowest priced products. Also, memory foam mattress have a strong chemical scent when they are new, and some users remain sensitive to the smell even as it dissipates. 

Latex Foam Mattress 

What is it?

Latex foam is a natural product made from the sap of the rubber tree, and is chemically similar to natural rubber. Mattresses made of latex foam are often made entirely of the material, and then covered in cloth. We have also seen mattresses being marketed as latex mattresses that are up to 60% synthetic. We have also seen mattresses that use latex as the top layer over a traditional inner-spring mattress. 

A pure latex mattress has many benefits: it provides a lot of support and naturally adjusts to the sleeper's position. Motion is absorbed, so motion of one sleeper will tend to not impact another person in the bed. Foam latex is warm in the winter and cool in the summer. A benefit that is unique to natural latex is that it is resistant to mold and mildew, and dust mites cannot live in this environment. 

Relative Popularity

Latex foam mattresses have been popular in Europe for some time, and are now gaining popularity in the United States because of their many advantages. One indicator of latex foam's growing popularity is that a number of mainstream mattress manufacturers have added latex foam mattresses to their product lines. 

Negatives

There are few negatives commonly associated with natural latex mattresses. Price might be considered a negative, as these are among the most expensive mattresses being sold. Bear in mind that foam mattresses usually last years longer than other mattresses. Although latex foam mattresses do not require frequent rotation, they are relatively heavy and difficult to rotate.