Hi litesleeper,
Unfortunately ... any of the Stearns & Foster so called "latex" mattresses in that range have a significant amount of polyfoam in the upper layers of the mattress which are the "weak link" of any mattress. While the amount of the polyfoam and the specific layering varies from mattress to mattress ... all of them are like this except the very highest end. In addition to this they use a lower cost/quality of latex (mostly synthetic Dunlop) which doesn't have the same type of response, feel, and elasticity as either blended Dunlop with a higher natural rubber content or best of all, 100% natural Dunlop.
You can see an
example here
of one of their "latex" mattress in a little higher price range (queen) than yours which has 3.5" of lower quality/density polyfoam over the "smart latex" (the mostly synthetic Dunlop) core. This means that you are sleeping on polyfoam not on latex with all the issues that are connected with using too much polyfoam in the upper layers of a mattress.
Rotating a mattress will have only a smaller effect on the softening and breakdown of the polyfoam (compared to flipping it which you can't because it's one sided) because in all directions the middle area will be the part that is bearing the most weight and softening the most. Rotating a king size one sided mattress by 1/4 turn can extend the life of any lower quality/density polyfoam that is used in the upper layers more than rotating it 180% but it is still lower density (cheap) polyfoam and will soften much sooner than other materials.
The problem with premature softening is that it isn't covered by warranty (it's considered normal wear and tear) unless the foam itself remains compressed more than the warranty exclusion without any weight on the mattress which rarely happens. The useable lifetime of a mattress has little to nothing to do with a warranty in other words and warranties are more of a marketing tactic than protection against a mattress that becomes unsleepable because of foam softening.
As you mentioned ... Sealy did buy Stearns and Foster which means that like all the other major brands ... they use lower quality foams and charge much more than other smaller manufacturers. They also don't disclose the details about the contents of their mattresses which means that most people who buy mattresses from chain stores or major brands are buying mattresses that contain foam that would typically be used in much lower cost mattresses made by local or smaller independent manufacturers ... and they have no idea that they are doing this. They tend to buy these brands or from mass market outlets based on marketing and advertising information (which is often completely misleading) rather than factual and meaningful information (which they don't provide). This is the reasons behind the
mattress shopping guidelines here
.
I would also check the foundation on the off chance that it is sagging in which case it could be part or all of the reason for what is happening but this is far less likely. If the foundation is completely solid and rigid and has no sags, then it is already like having plywood under the mattress so an additional firm layer will not help this. You could always try though to make sure that the foundation is as solid as it should be but this won't help if the issue is in the upper layers of the foam. You could also try a product like the
mattress remedy
or add other layers under the problem area of the mattress (such as rolled or folded towels or blankets or layers of firm foam) which will "raise" the area of the sag but these are imperfect solutions at best and don't address the real issues. They may give you some temporary relief however and extend the useable life of your mattress for a while.
Unfortunately it is much more difficult to "fix" a mattress that has lost it's support because of foam softening than it is to "fix" a mattress that is too firm and make it softer. You could turn the mattress over and add a topper but this is not the best solution because the softer foam will still affect your support and the other side is not designed for sleeping and is not "finished" with materials and ticking that are designed for sleeping on. Generally the "fix" in this case ... unless the actual depression in the mattress is more than the warranty exclusion (which is rare but would qualify you for a warranty replacement as long as all the other exclusions were also met) ... is to buy a new mattress. You may also be able to find a local manufacturer who will rebuild it by taking out the cheaper materials and then adding better materials in a comfort layer and putting a new ticking around it.
I wish I had better news but unfortunately this is an issue that is connected to the use of lower quality foams in the comfort layers of a mattress and is almost unavoidable unless consumers know how to make meaningful comparisons between the materials in a mattress and avoid mattresses and mass market outlets that don't provide the type of information that is needed to make better quality choices.
So your options are ...
- A warranty claim if you qualify (unlikely)
- Fixing the firmness of the foundation if that is the real issue.
- Putting something under the problem areas that will lift them
- Flipping the mattress and adding a topper
- Rebuild the mattress if this service is available to you (or "mattress surgery" if you wish to do this yourself)
- Buy a new mattress
Phoenix