In order to wake up feeling rested and pain-free, your mattress needs to be both supportive and pressure relieving. Many testing facilities use a test person and a test machine to measure how far the body sinks into the surface of the mattress and how well it keeps the sleepers spine aligned. A good mattress should keep your spine parallel to the surface and shouldn’t allow your body to sink in too deeply. To test how well the mattress isolates motion a large, stamp-like device applies pressure to one area of the mattress. If the mattress only compresses where the pressure was applied, then you won’t be disturbed by your partner tossing and turning next to you.