Here's a little backgound.  My back, and more recently, my hips have been hurting after a night's sleep.  I've been sleeping on my son's bed (he has a double, 3 year old) for the past week (and on/off since I bought it for him) and have woken pain free so I decided to purchess the same bed he has only in a Cal King.  Our bed seems harder than his and the one we laid on in the store.  Last night was my first night and again, my back and hips still hurt. My back and hips NEVER hurt while sleeping on his bed.  His bed is not on a box spring, it's on slats approx. 1" apart and the width of the bed.  My problem is that my bed feels VERY firm (like laying on a piece of wood) compared to my son's bed and the one in the store.  Does being on a box spring vs. slats make a difference?  Do we just need time to adjust to the bed?  Could we possibly have a defective mattress???  Any suggestions would be most appreciated.  Thank you.

The new bed is firmer because the one in the store has been layed on by many people over months or years. Hopefully you got a 30 day return privilege, so try it out for 30 days. Also sometimes our bodies need to adjust to a new mattress.

The same thing happened to me when I got my new bed in the summer. It definitely was firmer than the one in the store. So much so that I checked out everything on the label carefully and went back to the store to compare with the bed I tried there. Surprise - the bed in the store didn't have the label naming but and the salesperson insisted it was the same.

I can only assume it's true that all the people testing by bouncing, rolling and plopping down on the floor model softened it up. I got a soft topper for mine and it's perfect now. Actually, I'm glad I have it since I don't think the firm mattress,with less foam on top,  will indent as quickly as a plush, soft one would.