It is the age old question, is a hard bed or soft bed better for your back? We have heard for years that a hard bed is better for your back. When I did some digging it seems that the myth came about because old bed materials would compress over time. This would leave the user slumping down in a hammock type position. So people would put a board under their bed to stop the sagging. Which would make the bed hard.
Really though, it comes down to what is most comfortable for you. As research is improving, so are beds. It comes down to finding the bed that makes you feel the best. Though the best thing is to give a new bed time to see how you feel sleeping on it after a few weeks. It is just bes to remember what feels comfortable in the store for a few minutes may not feel comfortable every night for the next several years.
It is currently believed that a hard mattress will support a more neutral spinal position. Where a soft mattress is believed to help people reduce joint pain and back pain associated with aging. Hard mattress are thought to allow things like body pillows and pillows between the knees to be used more comfortably. Where research is allowing for better ways to support the body while still providing softness and comfort.
Studies have been done to try to compare the results on the body of sleeping long term on either a hard, medium, or soft bed but so far participants have not be able to stay with the study long enough to get a good read on results. Many of the participants on the hard bed dropped out well before the study was complete and many of the participants on the soft bed refused to begin the study as they did not wish to sleep on a waterbed which was the chosen soft bed for the study. Though of the soft bed participants who did manage through the study they felt reduced back pain compared to the users of the other two bed types. This data really cannot be used as of yet though since there simply were not enough participants on all bed types to get a good baseline. Hopefully in the future further studies can be done that will provide more concrete results.