The only way to determine what is right for your needs is to lie down on the mattress and let your body tell you if it feels right. If you sleep with a partner, you should shop together and test the mattress together. Don't be shy, this is an important decision that you will live with for a long, long time. Distribution of body weight. Most shoppers request a good firm mattress because this is one of the few objective terms they are accustomed to hearing with reference to bedding.
Shoppers often relate hardness to firmness.
There is a great difference between hardness and firm support. A too hard mattress doesn't have the flexibility to support the whole body. The support is greatest where body weight is greatest creating pressure points which will cause excessive movement during sleep. This movement is the unconscious reaction of the body to relieve the pressure and find a truly relaxed position. All the more reason to try out the sleep set at the store.