Memory foam mattresses provide a number of unique benefits. They are temperature sensitive, which allows them to conform to your body while sleeping. The result is a reduction of pressure points, which means less tossing and turning. Those with aches and pains can find relief with dense memory foam. On average, it's said to have a longer life span than innerspring mattresses. This is particularly true for the high density versions.

However, where there are advantages, there are usually disadvantages as well.

One of the most common complaints about memory foam is the chemical smell that is emitted, particularly when it's first opened. If you read customer reviews, you will see some who are completely turned off by it, and others who say that hardly noticed it at all. Then you have a middle crowd, who says that it bothers them at first but dissipated after a few days or week.

The truth is, some mattresses smell a lot more than others. Part of this has to do with where it's manufactured. The U.S. has strict regulations concerning what can be placed into mattresses, whereas other countries are less stringent.

What this means is that mattresses manufactured outside of the U.S. are more likely to have a strong chemical smell that persists, simply because they are able to add more chemical ingredients.

Even mattresses produced in the U.S. however have a new foam smell that may persist for a few days to a week weeks potentially. Some of the smell comes from the polyurethane base of the mattress. The other source is the chemicals used to make the foam, particularly the ones that are instilled to make it less flammable.

Ultimately, it smells because memory foam is not a natural material. It doesn't come from the Earth.

It should be noted however that this smell very rarely will cause some sort of health issue. There are exceptions of course, but it's not something that you should be overly concerned about.

The more sensitive you are to smell, the more it will bother you. The smell is often compared to that of gasoline or paint.

The smell is strongest right after you open it up. The reason is because memory foam mattresses are vacuum packed when shipped, so the smell is trapped inside for a specific period of time.

After awhile however, it does become hard to notice unless you stick your face right into the mattress.

Opening a window and airing it out some will make the smell more manageable upon opening it.