I just bought the serta icomfort savant 3 plush mattress king size - this is our first memory foam mattress.
The mattress was/is really comfortable however, I’ve noticed after 1 week, the area I sleep on has become significantly softer. It’s hard to say because this is my first memory mattress, but I feel a little increased pressure on my lower back/hips which is the area that is sinking in the mattress the most (where the most weight is). I actually prefer the feel on my wife’s side which has not become softer yet (shes 105 pounds, I’m 180)
I’ve also measured with a tape measure and it appears to be sagging by about half an inch in that area (when I’m not on the bed).
Is this normal? Does anyone have experience with this mattress?
We were really excited to get a soft, but supportive memory foam mattress.
There will also be a break in and adjustment period for any new mattress or sleeping system as the mattress loses any of it’s “false firmness” and the cover stretches and loosens a little and the materials settle and your body gets used to a sleeping surface that is different from what it is used to (see post #3 here). This would typically be a few weeks but it can be shorter or longer depending on the specifics of the person and the mattress (higher density materials can take longer) and it can be surprising to many people how much their sleeping experience can change over the course of the first month or so.
It’s also possible that the support system you are using under the mattress is sagging but you can test this by putting your mattress on the floor for a few nights to see if it makes any difference. If it makes a difference it could be your support system and if it doesn’t then it’s more likely to be the mattress.
I would also keep in mind that the major brands such as Sealy/Stearns & Foster, Simmons, and Serta all tend to use lower quality and less durable materials in their mattresses than most of their smaller competitors that will tend to soften or break down prematurely relative to the price you pay which is why I would generally suggest avoiding all of them completely (along with the major retailers that focus on them as well) regardless of how they may feel in a showroom along with any mattress where you aren’t able to find out the type and quality/durability of the materials inside it (see the guidelines here along with post #3 here and post #12 here and post #404 here).
There is more about the 3 most important parts of the “value” of a mattress purchase in post #13 here which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on suitability, durability, and all the other parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
While nobody can speak to how any specific mattress will “feel” for someone else or whether it will be a good “match” in terms of comfort, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) because this is too subjective and relative to different body types, sleeping positions, and individual preferences, sensitivities, and circumstances and you are the only one that can feel what you feel on a mattress … outside of PPP (which is the most important part of “value”), the next most important part of the value of a mattress purchase is durability which is all about how long you will sleep well on a mattress. This is the part of your research that you can’t see or “feel” and assessing the durability and useful life of a mattress depends on knowing the specifics of its construction and the type and quality of the materials inside it regardless of the name of the manufacturer on the label or how a mattress feels in a showroom or when it is relatively new so I would always make sure that you find out information listed here so you can compare the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
While your experience is very early in the life of your mattress so it’s much more likely to be the result of the mattress breaking in … more rapid foam softening after the break in and adjustment period would also be typical for a mattress that uses lower quality/density materials that will tend to soften and break down much more quickly than higher quality/density materials and which can lead to the premature loss of comfort and support and the need to replace a mattress much more quickly than you would otherwise have hoped for. Unfortunately foam softening and the loss of comfort and support isn’t covered by mattress warranties unless they also have a visible impression in the mattress that is deeper than the warranty exclusion (see post #174 here).