Hi sdmark,
I completely agree with your thoughts about reviews when it comes to mattresses (see post #13 here) which is the main reason I focus so much on the materials in a mattress and on helping the members here to have a better understanding about what to realistically expect with a new mattress purchase. Knowing the materials inside a mattress is really the only way to make meaningful quality, value, and relative durability comparisons when you are buying a mattress
The durability of a mattress (or more accurately the useful life of a mattress which is relative to each person and is not just a function of the materials themselves) is a complex subject with many interacting factors involved. There is more about this in post #4 here.
In any mattress … it’s the upper layers that are subject to most of the compression forces that soften, change, or break down the materials and are normally the weak link of a mattress. This is why its so important to know the materials in the comfort layers especially and identify any potential weak links in the mattress. This means that the top 3" to 6" or so (depending on the other factors mentioned in the durability post) are the most important from a durability and longevity point of view.
There are also two main changes that happen to mattress materials over time. These are changes in firmness (foams will soften and fibers will compress and become firmer) and changes in height (both foams and fibers will lose height over time although there is a significant difference in how much this will happen to different materials).
In the case of the Dreamfoam Ultimate Dreams … these upper layers are the 1.5" of quilting foam, the 3" of latex, and in some cases depending on individual circumstances, the support layer on the bottom.
The quilting foam is in the range of “about an inch or so” which is thin enough and already soft enough that any further foam softening will normally have little effect on the useful life of the mattress. It is also quilted which pre-compresses the quilting and makes it more durable as well. Even if this softened significantly it’s main function is the surface “feel” of the mattress and there isn’t enough thickness that foam softening would have a significant effect on the overall feel and performance of the mattress.
The layer underneath this is latex which is the most durable foam material in the industry … although as you can read in the durability post, softer latex is less durable than firmer latex (this is true of any foam material).
Underneath this is the 1.5 lb polyfoam (NOTE they are currently using 1.8 lb polyfoam) which for most people would not play the most significant role in the useful life of the mattress but in some circumstances (such as heavier weights or for people that are “on the edge” of a mattress that is too soft for them … see post #2 here) this can also play a role and a higher density base foam would be a better choice.
This is also one of the lowest budget mattress and among the least costly mattresses you will find anywhere that includes 3" of latex in the comfort layer.
Having said all that … there is no soft material that is immune from some softening or impressions and it’s just a matter of degree and on how much the foam softening affects the comfort and support of the mattress for the person using it.
In addition to this … the hills and valleys that can form in a mattress are a separate issue as well that are not only connected to foam softening (although that can play a role). This is particularly common in the larger sizes … especially king size. There is no way to avoid this completely because in most cases the middle of the mattress isn’t used as much as each side so it’s really a matter of degree and time. It can come from either the loss of height as lower quality foams break down and fibers compress or it can come from the gradual stretching, shifting or “bunching” of the materials in the center of the mattress where nobody sleeps. This would be more common with quilted covers. In addition to this … you can also have “virtual” impressions where there isn’t a visible impression when there is no weight on the mattress but where the softness of the mattress or the softening of lower density materials allow the heavier parts of the body (usually the pelvis) to sink down too far even though the foam hasn’t lost significant height. These virtual impressions are more connected to either the softness of the original choice or the loss of ILD (foam firmness) that is much more common and develops much more quickly in lower quality/durability materials than it would with latex.
Outside of buying something that has no give at all and will stay completely flat (and is too firm to sleep on), there is no way to completely avoid the normal changes in a mattress or the materials inside it that happen over time and it’s just a matter of degree and on how much these changes affect comfort (pressure relief) and support (alignment). Because some degree of softening and shifting and loss of height is a “normal” occurrence with all materials to different degrees … mattress warranties have exclusions for the amount of impressions that are considered to be a defect. Without this every mattress sold would qualify for a warranty exchange with the slightest amount of change in the materials and this wouldn’t be realistic.
Most warranties cover loss of height past a certain point and not changes in comfort and support. Normally the warranty exclusion for a mattress that has quilting of some kind or polyfoam in the comfort layers is from 1.5 - 2" and a warranty exclusion for a mattress where you are sleeping directly on a higher quality specialty material such as memory foam or latex that is less prone to the loss of height is .75". The larger exclusion for quilted covers is to allow for for some softening, compression, impression, and shifting of the materials in quilted cover. Even wool which is one of the highest quality materials in a mattress and is found in mattresses that cost multiple tens of thousands of dollars can compress over time up to 30% of its thickness although this varies depending on how the wool is compressed, the type of wool, and how it’s made and tufted. The manufacturers of ultra premium mattresses will tell you to “expect” this “nesting” but of course many consumers believe that if they paid tens of thousands of dollars for a mattress that it won’t impress at all which of course isn’t realistic.
In addition to this there are also other factors that can contribute to the ridge in the middle of a mattress. This includes using a box spring instead of a non flexing foundation or platform bed … particularly in a king size where there are two twin XL box springs with solid wood non flexing edges that meet in the middle and each side over the springs themselves is more flexible which can contribute to the formation of the ridge in the middle. Foam mattress tend to do best with a support surface that doesn’t flex anywhere at all over the entire surface (with a few exceptions that are part of the specific design of some sleeping systems) which helps the mattress surface remain more even.
Finally there is the issue of legitimate defects in the materials that are in the mattress. All foam suppliers produce defective or “out of spec” materials from time to time and these can end up in a mattress. Even latex that has voids in the material or wasn’t properly cured in the middle of the material can be defective. These will always affect some smaller percentage of mattresses and tend to show up early in the life of a mattress and are the main reason for a warranty in the first place (you can read in post #174 here how warranties have little to do with the useful life of a mattress). Some of the larger manufacturers use the exclusions in their warranty as a way to avoid warranty claims. Many smaller manufacturers who are more responsive to their customers have warranty exclusions to make sure that warranty claims are reasonable and will lean towards the customer in the grey areas of warranty claims because they are more concerned about their reputation than avoiding a legitimate warranty claim.
The real issue in a mattress and the main factor in its useful life is the loss of comfort and support regardless of whether the sleeping surface is completely flat … and there are many consumers who have unrealistic expectations and believe a mattress has failed at the first sign of any impression at all or when the middle of a larger size mattress develops a ridge of any kind. This just isn’t a realistic assessment if the foam materials underneath them are still providing them with the comfort and support they need or if the changes are inside the “normal” range for the type of mattress they purchased. If the mattress is still comfortable and provides good pressure relief and keeps you in good alignment … has impressions that are less than the warranty … and the materials in the mattress have only softened to the degree that is reasonable for those materials … then the mattress is doing exactly what it was intended to do. If they were to sleep on the center of the mattress as often as they do on each side (which of course isn’t practical for most couples) then the mattress materials wouldn’t stretch or shift and the mattress surface would remain more even or even out over time.
So all of this really depends on the specifics of each circumstance, on the actual reasons behind why each person is having an issue with their mattress (vs the reasons an unhappy consumer may sometimes believe is the issue), and on whether their issues are legitimate and reasonable and are connected to the mattress itself or due to other reasons that may have little to do with the mattress itself.
If you know the materials that are in your mattress and make sure they are the best quality available for the budget range you are in … then your odds are significantly higher that you can avoid or reduce these types of issues in the first place although they will never be eliminated completely and of course there will always be consumers that believe their mattress has failed at the first sign of changes that are completely normal.
Phoenix