One of the most misunderstood aspects of the bedding industry is the body impression. All beds regardless of size, type, brand, type, firmness, cost, or quality will form body impressions. Not only is a body impression not a defect it is a desirable occurrence. Much as you make your footprint in the sole of a sandal, you make your “bodyprint” or “body signature” in your mattress. Here are some facts about body impressions:
While all beds will form them, plusher beds tend to show them a bit more than firmer beds.
They will form quickly, usually with in the first two to six months. However, once formed they do not continue to deepen.
They are visual; but, you cannot feel them.
A king sized bed may appear to have a ridge down the center because the body signatures of the two people sleeping on it are usually further apart than on a queen.
Newer products tend show them more than the beds of yesteryear. This is because modern materials are better and beds are, on average, plusher than they used to be.
The premium foam products (memory and latex) will generally form shallower impressions. You will still (and want to) get them.
To make a mattress that will get no body impressions it would have to be incredibly HARD. So hard that you could not sleep on it.
Certainly, there must be a distinction between a body impression and a sag. While standards differ from company to company, generally a depression exceeding 1 1/2 inch on an innerspring mattress or 3/4 inch on a foam mattress would be cause for concern. Most new mattresses will carry a manufacturer’s warranty. This warranty should address the specific depth required to consider it to be a candidate for replacement. At this point you should contact you retailer (or the manufacturer if that is not possible) and begin the warranty evaluation process.