WHat the salesman won't tell you

I hate this mattress. I like a firm mattress; we got the firmest one available. Felt great at the store. The salesman didn't explain anything about a "break-in" period, whereas, after a while the mattress gets softer and softer. While you sleep, the mattress will compress forming a deep trench tour body lies in. If you want to roll over, you have to wake up enough to lift yourself out of the trench &/or flop over. This trench eventually "bottoms-out" against the foundation; negating the form fitting effect. Unless you weigh 90 lbs like the model in the other brand's ads, you will experience the same thing. Additionally, if you sleep on your side, your mid-section & thighs (which are heavier than your lower legs,) will form a "v" trench in the foam. This puts negative pressure on the lateral and medial ligaments in your knees. Care has to be taken not to move in such a way as to hurt them while you sleep.If I hadn't spent so much on this, I would have replaced it by now. OBTW, the return period for the mattress was just under the length of the manufacturer recommended break-in period...Still waiting for a really great nights sleep. P/S, my back hurts worse with this than with the one it replaced.