About Memory Foam & Latex Foam

• Down-filled mattress pads (featherbeds) and polyurethane foam pads give your bed softness. But Beds.org notes that two high-density foam pads, those made of memory foam or latex foam, yield more noticeable changes to the feel of your mattress. Both of these foam pads conform to the body, relieving pressure points and promoting more restful sleep.
  
  Memory foam, also called "temper foam," has actually been around since the mid-1960s, although it wasn't used in commercial bedding. It was originally developed by NASA's Ames Research Center to absorb shock in airplane seats. Memory foam, which is derived from plastic, has been used in everything from football helmets worn by professional football players to mattresses in hospital beds, and has also found its way to the consumer market.
  
  Latex foam, which is derived from rubber and therefore springier and more elastic in texture, has a less glamorous history. But latex foam is memory foam's heated competitor in the market of mattresses and foam pads. As of October 2009, sales of latex products had increased more than 49 percent during the prior four years.
  
  

Purchasing High-Density Foam Pads

• When purchasing a memory foam or latex foam mattress pad, there are three variables to consider: the foam pad's density, thickness and indentation load deflection (ILD).
  
  Depending on where you shop for your foam pad, you may find them available in densities of anywhere between two and six pounds (per weight in 1 cubic foot), thicknesses of between 1 and 6 inches, and varying ILD ratings. A memory foam or latex foam pad with a density of under three pounds and less than 3 inches will provide marginal benefits, while those over a density of three pounds and 3 inches thick (or more) can change the feel of your bed.
  
  Density is typically relied on to gauge the firmness of the foam pad. But this isn't necessarily true across the board. Beds.org advises that you also defer to the pad's ILD rating. An ILD rating of 15 or below in a memory foam and an ILD rating of 28 or below in latex foam gives the foam pad softer, more conforming properties.
  
  

So What's the Difference?

• The primary difference between memory foam and latex foam pads is how quickly the material springs back once weight is applied. Memory foam returns to its original shape slowly--if you apply pressure to the foam pad with your hand, it leaves behind an indentation upon release that gradually springs back. Latex foam pads have a more elastic texture and automatically spring back after weight is applied and released. Memory foam also relies on body temperature to maximize its contouring properties, while latex foam instantly conforms to the body's shape as soon as your head hits the pillow.
  
  Both types of foam pads are ideal candidates for those who want to avoid back pain associated with a too-soft or too-firm mattress. Both are antimicrobial, making them resistant to dust mites and mildew. However, memory foam and latex foam pads work best when your existing mattress is still in relatively good shape, free of any existing lumps or sags.