Warranties last longer than sleep trials, but they only cover a limited range of issues. Under the terms of a trial period, you can test out the mattress and return it for a refund even if it has no defects. By contrast, a warranty protects the shopper in the long term against defects in the mattress' materials and workmanship, and the company gets to choose whether to provide a refund, repair, or replacement. Mattress companies closely evaluate warranty claims, and refunds or repairs are often prorated based on the age of the mattress.