Memory foam is made from polyurethane with additional chemicals that add to its viscosity level, thereby
increasing its density. It is often referred to as visco-elastic polyurethane foam. Depending on the chemicals
used and its overall density, it is firmer in cooler temperatures and softer in warmer environments.
Higher density memory foam reacts to body heat which allows it to mold itself to the shape of a warm body within
a few minutes. A lower density memory foam is pressure-sensitive and will mould more quickly to the shape
of the body.
The example often used to demonstrate its properties is that a hand pressed into the foam and
then removed will leave a clear impression in the foam.
Memory foam was originally developed by NASA to ease the pressure of extreme G-force during space shuttle
take off. It was never used in the space program, but was subsequently used in medical applications, for
example with patients suffering from pressure sores or bed-bound for a long period. Its most common domestic
applications are memory foam mattresses, pillows and mattress toppers (also known as mattress pads). It remains useful in
medical-related uses, such as wheelchair seat cushions, hospital bed pillows, and padding for persons suffering
long-term pain or postural problems; for example, a memory foam cervical pillow may alleviate chronic neck pain.
Its heat-retaining properties are also helpful to some pain sufferers, who find the added warmth helps alleviate pain.
A memory foam mattress is usually denser than an ordinary foam mattress. This makes it more supportive -
but also heavier. It is often seen as a good compromise between the comfort of a soft mattress and the
supportiveness of a firm one. Memory foam mattresses often last longer than traditional mattresses.
