We purchased a Kingsdown Sleep to Live mattress from Sleepy's in early July 2009. The first mattress had a very clear sag in the center of the mattress to the point that we sank way way down into the mattress and felt that we were lying far below the level of our feet. Sleepy's was good in that they replaced the mattress immediately at no charge and the second mattress seemed better for about two weeks. Now, it too, is developing the same sag as the first one. My husband and I are slender, no more than 150 pound between the two of us, so we can only conclude that this mattress design is defective. Before we purchased the mattress, we had extensive conversations with Sleepy's personnel about Kingsdown's past problems and the way they had been rectified in this new design. I suppose we were stupid to have believed them; we really liked the feel of the mattress and allowed that to blind ourselves to what should have been obvious.