sorry for the delay - don't visit the forum consistently. It did not sink in 7 inches. The Ara had 7 inches of memory foam. We had both the mattress and the foundation. I liked it more than my husband because I don't sink in as much. When you first sit on the mattress it feels like a rock, then in seconds it sinks in. For my husband he felt like he was trapped. He only weighs 160 lbs. We didn't get it for any specific back pain reason but several aches and pains while sleeping, hips, numb shoulder, pressure points.