The Visco Elastic Foam Mattress: A Memory Foam Buyers Guide

By now you've seen the commercials for memory foam demonstrating how it conforms to your back and how you can jump on the bed and not spill your wine. But for the average consumer, there are more important facts:what are the different types and what do they mean, what are the advantages and disadvantages, and of course, how much is it going to cost.

A Brief History

The visco elastic foam mattress (known more commonly as memory foam) was first developed by NASA in the 1970s. From there it moved to the medical field, becoming available in the 1990s in beds and wheelchairs to relieve pressure sores. It's first manufacturer was Tempur-Pedic, and due to its medical roots, Tempur-Pedic mattresses tend to be more expensive than others on the market today. As reports of patients suffering less pain and getting better sleep came in the product began being offered to the general market.

What It Does

Memory foam is made up of open cells, meaning they have several holes in them. This allows the mattress to compress fully without springing back. These cells also respond to body heat, allowing the mattress to become softer at higher temperatures. The mattress itself is composed of two parts, the top memory foam layer, and the denser core layer. The core layer is necessary, since a mattress composed completely of memory foam would be far too soft.

Buyers Guide

There are several factors consider when buying a memory foam mattress. The first is the ILD (indentation load deflection) of the foam itself. The ILD is the force required to make a 1in deep depression with a 50in disc in a piece of foam that measures 15 x 15 x 3in. Put more simply, it is the firmness of the memory foam. An ILD of 10-11 is considered soft, an ILD of 12-16 is firm, and an ILD of 16-20 is extra firm. Most mattresses fall in the 12-16 range. Another term for this is IFD (indentation force deflection), but it means the same thing as ILD.

The next factor to consider is the density of the foam, measured in pounds per cubic foot. You should look for a mattress that measures at least 3 lbs density, as anything else won't provide enough support. Denser foam is generally better for support and is more durable, but it will trap more heat.

Thickness of the memory foam layer is also crucial to finding a comfortable mattress. Anything less than 3in probably won't provide much support, while anything over 6in will be too deep. Some mattress companies will suggest a thickness of 2in if you sleep on your stomach, however.

Some companies will offer memory foam with heat reduction channels, grooves cut into the foam to increase ventilation. Since too much trapped heat is a frequent complaint of memory foam users, it might be a feature worth considering. It will, however, make your mattress more expensive.

Memory foam mattresses do tend to be more expensive than ordinary spring mattresses. They range from around $300 to well over $1000. Some of this has to do with the size and features of the mattress, but some of it also has to do with quality. Beware of memory foam mattresses that seem unusually inexpensive, as these are often inferior products.

Advantages of Memory Foam

Memory foam mattresses contour well do the body, thus relieving pressure points. They can ease joint pain and back aches, and make for more restful sleep. Since motion is not as easily transferred, you are also less likely to disturb your partner if you share a bed. Furthermore, memory foam generally houses fewer dust mites, which can be a benefit to allergy and asthma sufferers. They have also been known to be more durable than regular mattresses, less likely to sag, and more resistant to mildew.

The Disadvantages

As mentioned above, memory foam traps heat much more than regular mattresses. This can be a good thing in the winter, but uncomfortable in the summer. New mattresses are often reported to have a chemical smell similar to paint and must be aired out for several days when first purchased. While the smell does fade, some of it may linger and cause respiratory irritation, depending on the sensitivity of the one using it. Memory foam may also be unsafe for babies and small children, since they will have more difficulty turning over and could suffocate. It should be mentioned that while ILD ratings are a good starting point, temperature and humidity do alter the softness of the foam to some degree. It is important to test out the mattress yourself before buying.