My husband and I bought a sleep number 12 years ago (when they were simply Select Comfort beds) because he likes to sleep on something as hard as a floor, while I prefer something more like a waterbed. We first had a problem with him rolling over onto my softer side continuously, to the point he was so uncomfortable trying to balance. Selelct Comfort sent us an extra foam pad to help, which didn't, really. Now, the bed is breaking down and the middle caves in, even at the firmest setting. My husband and I haven't slept in the same bed in years because he is so uncomfortable in this bed from day one. I wake up most mornings with back pain that goes away after a couple hours up.