Sheets with a sateen weave put more threads on the surface for a softer feel and added sheen to the fabric, and the 400-thread-count  Sheets live up to these expectations. They are among the softest bed sheets tested by a consumer testing organization and receive high marks for quality construction, little shrinkage and a good fit on a mattress measuring 17 inches deep. One notable feature on the fitted sheet is an unusually wide elastic band that creates a secure fit.