I got the 10 inch memory foam mattress and discovered all my favorite sheets did the same thing. I had a choice, find a solution or buy even more sheets, which wasn't an option, so I carefully and accurately drew a line all the way around the sheet about 6 inches from the edges, cut on the line, and put in a 8" wide piece of blending fabric and sewed the edges back on. Works great and much cheaper than buying new Egyptian cotton sheets, and who cares what is holding it on as long as what touches me is soft.