This bed arrived three days after the purchase. On the first and second night I was acutely aware I was lying on a different mattress. On the fourth night, pain in my lower back stopped, but I developed pain in my upper back. After 11 days the pain was worse. I was told by Ghostbed that I could not return the mattress until day 30. So, I persisted. On day 17 the pain in my upper back was gone and the mattress began to feel very supportive. I am now at day 27. I am not going to return the mattress. It appears to be correcting my posture. I feel more rested after shorter periods of rest. I recommend sleeping on the mattress for at least 30 days before making decisions. By the way, I have a big Boxer called Willbur. He weighs 80 pounds and I cannot get him off this mattress.