Memory foam, sometimes referred to as viscoelastic foam, has auspicious beginnings dating back to the mid-1960s, when NASA's Ames Research Center developed a similar material called "temper foam" for airplane seats to give them better shock absorption. Memory foam, the spin-off product developed for the consumer market, has been used in hospital bedding, to line the soles of shoes and even padded the helmets of professional football players. According to NASA, memory foam was first called "slow spring back foam," because the material "flows" to match the contours of the body and slowly returned to its original shape once body pressure is removed.
Due to the popularity of viscoelastic bedding, other foam bedding types have found their way into the consumer market as well and are considered an acceptable substitute for traditional box spring mattresses. Latex foam is a heated competitor for memory foam in the bedding industry. Derived from rubber rather than plastic, latex foam has more elasticity and is quicker to return to its former shape once compressed. Latex International notes that latex foam mattresses are "breathable," yielding more warmth in winter and more coolness during the hotter months.
One factor consumers should consider when looking for either memory foam or latex foam is the mattress' or mattress pad's density rating. Density is most closely associated with firmness; the higher the density rating, the firmer the mattress or foam topper (although the health care professionals from Beds.org note that this isn't always the case). Foam mattress toppers are sold in a variety of densities, as well as levels of thickness, which can range between one and six inches.
Beds.org notes that another factor to take in consideration is the foam's indention load deflection (ILD) and points out that most people prefer an ILD of between 10 to 16 in their memory foam mattresses. When it comes to external memory foam or latex foam mattress pads, Beds.org states that an ILD of 15 or under or an ILD of 28 or under, respectively, make the softest, most conforming foam mattress pads.
Both types of foam are naturally antimicrobial, resistant to dust mites and mildew, and both purport to relieve pressure points and encourage more restful sleep. Ultimately, the biggest difference between latex foam and memory foam is the spring-back action of these two types of foam. Memory foam, which relies on body heat to exert its conforming properties, is slower to depress and release. Latex foam is more similar to traditional box spring mattresses in that is instantly conforms to the body and has a quick spring-back and bouncier feel.