Foam mattresses may adjust to your body and form shallow body impressions. These impressions are normal and do not jeopardize the support or integrity of the mattress.
However, Nolah's mattress warranty does cover significant deterioration of a properly-used mattress. The warranty terms define deterioration as "visible indentations of more than 1 inch." To remain eligible for warranty coverage, you must use your mattress on a proper foundation or base, not exceeding the weight limit stated in the warranty.