Several studies have measured the difference between mattresses—including a chiropractor-led study that looked at two factors: spinal distortion and maximum pressure. The researchers concluded that the two goals of a mattress were to exhibit LOW maximum pressures and LITTLE spinal distortion.
Another study, this time from a team of South Korean researchers, found that participants gave the highest ratings when their spinal curve while lying down was similar to their standing spinal curve. This prompted a six-day/night follow-up study where researchers measured brain waves, eye movements, heart rhythm, chin movements, and body temperature overnight in a sleep laboratory. They found that sleep efficiency and deep sleep percentages were higher AND the participants woke up less often when the participant rated the mattress as “comfortable”.
A Spanish study found a connection between higher comfort scores how well the pressure of a user’s body distributed over the mattress.
Another study that included 313 adults with chronic low back pain divided participants into two groups that slept on either a medium-firm or a firm mattress for 90 days. The study found that those on the medium-firm mattress had the best outcomes for pain in bed, pain on rising, and disability.
So after ADDING up ALL these findings, it appears that doctors should recommend a mattress that does not distort the spine, distributes weight evenly, and is medium-firm in density.