We got the Sleep Number with the pillowtop a couple of months ago, desperately hoping it would help my back. It hasn't helped my back - of course, in the meantime I've learned that it is muscle spasms, not the structure of my back, that hurts. I am not used to it yet, as most of my nights are spent on the recliner in the living room.
HOWEVER...my husband has always been an extremely light sleeper, and often found it difficult to get his rest. Since we got the Sleep Number and he cranked his side down to about 55, he absolutely hibernates. There is a marked improvement in his sleep, and he adores it.
