Memory foam mattresses, over the last 10 years or so, have become increasingly popular in the bedding retail market, and for good reason. Memory foam was initially developed for use in the NASA space program years ago, to protect astronauts during G-force re-entry into the earth's atmosphere, because of its pressure relieving properties. It was never used in space flight, due to potential off-gassing in an enclosed capsule. Several years later, a company called Tempur-Pedic® began developing a mattress for hospital and post-surgical patients, in order to relieve bed sores and reduce pressure points for those patients who had long term stints in a hospital bed. As the years went on, the reputation from positive results for these patients, due to the pressure point reduction and comfort value properties of the memory foam mattresses, led Tempur-Pedic® to consider a retail avenue for these mattresses. This is how memory foam mattresses evolved into the retail bedding industry.

Memory foam mattresses are NOT made entirely of memory foam. Memory foam is situated as a layer of foam (typically several inches thick) on top of a thicker layer of polyurethane core foam (the base or superstructure of the mattress. These layers are laminated together with varying types of adhesives to keep them from coming apart. Look for a memory foam mattress using at least 3.2 lbs. density memory foam in its memory foam layers. You need this minimum density to assure that the memory foam will last and reduce pressure points. Underneath the memory foam layer/s again is the polyurethane core portion of the mattress. This core should be 6" or more of high density foam, and the density of this core foam should preferably be 2.0 lb density or higher.

Memory foam is derived from petroleum. The petroleum is converted into a polyurethane foam. Additional chemicals are added to the polyurethane, that increase its viscosity level, which increases its density. Memory foam is typically referred to as visco-elastic (or heat sensitive) polyurethane foam. Depending on the chemicals used and its overall density, Memory foam is typically firmer in cooler temperatures and softer when warm. Higher density Memory foam reacts to body heat which allows it to soften and contour to a person's body within a few minutes. Lower density foams typically mold more quickly to the shape of the body as it heats up. I'm sure you've seen by now the often used image or video of the handprint left in the memory foam after pressure is applied, which is an example of this molding and conforming nature of Memory foam.