Every night, the fitted sheets come off this mattress. We have tried everything. When we complained to the store where we bought it, the salesperson said he has many similar complaints. Said he could not do anything about it, but some people have spent hundreds of dollars buying a different cover to fix the problem.
Bottom Line--DON'T WASTE YOUR MONEY. Buy a TempurPedic. I have owned two, and have never had any problems.