What’s in a memory foam mattress
Memory foam—also known as viscoelastic foam—is high-density polyurethane foam that softens in response to heat and pressure, which is what allows it to mold to a sleeper’s body. Engineers working for NASA developed memory foam in the 1970s when they were looking to invent a material that would provide better seat cushioning and crash protection for airline pilots and passengers. In addition to mattresses, pillows, and mattress toppers, memory foam is also used for furniture cushions and in some car upholstery.
Mattresses in the memory foam category are typically not 100 percent memory foam; the material is so soft that it wouldn’t provide enough support all by itself. Only the upper, or “comfort,” layers are memory foam. The rest is a support core that’s made from denser polyurethane foam or, in the case of a hybrid mattress, a combination of foam and innersprings.
Some memory foam mattresses have additional support layers of varying densities and special features like cooling gels or moisture-wicking fabrics, designed to combat the material’s natural tendency to trap body heat.
"When you lie on the memory foam, the heat from your body softens it in appropriate points," Arand says, "so this helps to support your body along the curves and natural lines of the body." Memory foam manufacturers claim this helps relieve pain and thereby promotes more restful sleep. And, though consumers often believe that very firm mattresses are best, more "giving" mattresses like these may lead to better sleep in people with back pain, according to the National Sleep Foundation.
What Are the Disadvantages of Memory Foam?
Gromer says that memory foam products may retain body heat, which could make them less comfortable in warm weather. However, Arand has not heard this complaint from her patients. "In our culture, most people can adjust their thermostats or blankets for the appropriate season," Arand says.
When new, memory foam can produce an odd chemical smell -- a phenomenon called offgassing. To minimize this problem, the Sleep Products Safety Council, a sleep products trade group, recommends airing out the mattress or pad for at least 24 hours before putting sheets on it. "If you follow directions, the smell dissipates quickly," Arand says, "But I've never heard of anyone having reactions to it."
So do you know what the memory foam mattress?