I have one of those 18 inch thick memory foam mattresses (not too fond of it either). It is nearly impossible to lift the corners to slide the edges of the sheets under it. Elastic bands added would be impossible to slide under. Our headboard and footboard are curved around so we cannot get our hands under the mattress top and bottom. My husband had our bedroom furniture custom made, and I truly love it....BUT the mattress is just unforgiving. He constantly complains about the bottom sheet popping off the mattress. We may change it out next year and I am wishing for regular mattresses that you can flip over and be able to lift to put the sheets on.