Memory foam is a fairly new development that uses polyurethane and other chemicals to create a temperature and weight reactive foam that takes the shape of what lies on it. This foam is also referred to as visco-elastic foam and was developed under NASA, but never truly used by them. The density of memory foam is significantly higher than other foam beds and makes for a heavier, more expensive mattress.
Memory foam mattresses have a 81-percent high customer satisfaction rating. Owners give high praise to the cloud-like feel of the memory foam. It seems to move with a sleeping body throughout the night. Without issues like spring compression to combat, memory foam mattresses have an above-average lifespan and level of durability.
When memory foam reacts to body heat it becomes soft and can give off a strong off gassing odor when new. A caution to consider when buying a memory foam mattress is what fire retardant is used in the materials of the bed. Memory foam being made from polyurethane is flammable and under law must contain some sort of fire retardant. Certain fire retardants have been linked to health problems including cancer.