The warranty on the new mattress and foundation you purchase is not an indicator of how long the product should be used before replacement. The mattress warranty is there to protect the customer from product defects, not against the gradual loss of comfort and support.
What about the Warranty?
Moreover, different manufacturers offer different mattress warranties, and you should check with the manufacturer of your mattress for product-specific information.
Is it normal for my mattress to get body impressions?
Yes. Many of today’s top-quality mattresses use extra-plush foams and fibers to create comfort layers designed to cradle your body and relieve pressure. The first few weeks you sleep on a new mattress with extra comfort layers, you will likely notice some body impressions on the surface. These impressions are normal. They indicate that the comfort layers are conforming to your body, as they are supposed to do, and shouldn’t be considered a sign that something is wrong with your new mattress.