Hi mermia,
I wouldn’t pay much attention to reviews (see post #13 here) unless you know the exact body type, sleeping style, and preferences of the person writing it because “comfort” is so subjective and subjective perceptions of other people (or even our own subjective perceptions) are not a good way to choose a mattress. Basing a decision on subjective perceptions of “comfort” probably has lower odds than random chance alone of choosing the most suitable mattress (see this study). A mattress that feels “comfortable” for one person or even hundreds of other people may be completely unsuitable for another. Each person’s needs and preferences are based on body type, sleeping positions, and personal preferences and how their specific body type and sleeping profile in all their sleeping positions interacts with the specific construction of the mattress.
Support is also misunderstood because different parts of the body need different levels of support and the goal of a mattress is not so much “support” in the sense of firmness but to keep your spine in its natural alignment in all your sleeping positions. This means that some areas of the body (such as the heavier pelvis) need more firmness underneath them which can “stop” the pelvis from sinking in too far (which tilts the pelvis which in turn is the main factor which controls the lumbar curve) while other areas of the body such as the shoulders of side sleepers need enough softness and thickness in the comfort layers to “allow” them to sink in easily enough. If the comfort layers are too firm then the shoulders won’t sink in far enough and the upper body would be “held up” with too much weight on the shoulders and you would not only have pressure points but alignment issues as well even though the mattress is firmer and “more supportive”.
In general you need good primary or “deep” support to allow the pelvis to sink in “far enough” but no further and also “enough” softness and thickness in the upper layers to “allow” the shoulders to sink in enough for good pressure relief and to provide the “secondary” support that will fill in the recessed gaps in the body (such as the waist or small of the back) so that they are well supported as well. This combination of “stopping” and supporting some parts of the body while at the same time “allowing” other parts of the body for all the infinite different types of bodies and sleeping positions is the goal of all mattress design and theory. Of course this example were shoulders need to sink in applies more to side sleeping but the idea is the same for all sleeping positions and spinal alignment and pressure relief that is suitable for each person is the goal of all mattress purchases. This along with each person’s personal preferences and making sure that the quality of the materials are good enough to maintain their performance over the long term without undue softening anor breaking down prematurely will translate into long term “comfort” and healthy sleep when you sleep on the mattress at home.
Each person has a different weight distribution and also a different surface area in each part of the body that contacts the mattress and it’s the pounds of force per square inch in each area of contact that controls how far that area of the body sinks in to the mattress. As you sink in deeper then the surface area changes while the weight stays the same (the hips for example are wider and have more contact area as they sink in more which spreads the weight around a larger surface area and reduces pressure) and once the shoulders sink in enough then the the torso also begins to contact the mattress and the surface area of contact becomes much larger there as well. Some sleeping positions don’t have “bony prominences” such as shoulders and hips and need thinner and firmer comfort layers because you don’t need to sink in as far. Eventually the pressures and surface areas even out which stops further sinking in in all the areas of the body. When you come to rest in each different variation of your sleeping positions then your spine and joints need to be in neutral alignment.
The reason that this is so important and that I’m mentioning it is because it’s complexity makes it impossible to predict which set of mattress specs (assuming they are even available) will create good alignment in any individual person and only your own personal testing and/or experience can tell if a mattress has the “support” you need in all the different areas of the body to keep your spine in good alignment in all your sleeping positions. This is why personal testing that is more objective and careful and follows the testing guidelines I suggest is much more effective than assessing any mattress for how “supportive” it is for any particular person.
The good news though is that if a mattress is too firm then it’s relatively easy to add some extra softness to the surface with a topper to “allow” the parts of the body that need to sink in a little more as long as the topper isn’t so thick and soft that it also “allows” the pelvis to travel too far before it reaches the firmer comfort layers. It’s much harder to “fix” a mattress that is too soft in the deeper support layers or too soft or thick in the comfort layers because making either of these firmer would involve removing and replacing the foam or component with firmer versions rather than just adding a firmer layer on top of them. Firmer layers or toppers will still sink into the softer layers below.
So if your mattress is a little on the firm side then it’s a much “safer” choice than a mattress that is too soft because foam softening may correct it over time or you can always add a topper.
If you are considering a mattress that you haven’t tested in person then you would be dependent on the knowledge and experience of the person you are dealing with and their ability to predict how well the mattress you are choosing will interact with people that have a similar body type, sleeping style, and preferences as you do based on the “averages” of their customers. This is as much guesswork as it is an art and science. In these cases your recourse if your choice turns out to be less than ideal is a big part of offsetting the risk you are taking when you are considering a mattress you haven’t tried and trusting the “best efforts” of someone that can easily make a mistake with all the complexities involved. If you are confident that the mattress if anything will likely be firmer than you need or prefer then the choice is safer than if it turns out to be too soft (unless you can exchange it again).
For the Directions mattress, from the perspective of PPP this would depend on the results of your testing. If you aren’t able to test it in person then it would have a higher risk and would depend on the level of risk you are comfortable with and on your recourse if it turns out that it wasn’t suitable for you. From the perspective of durability and quality (how long the mattress will maintain it’s comfort and support over time as the foam and other materials soften or break down) it would depend on knowing the density and quality of the foams which Serta doesn’t disclose and it may take some time for this information to become available (if they ever disclose it at all). Based on some information I have I believe that the dual action gel memory foam in the Directions is high quality and in the range of 5 lbs density but I don’t know any of the other specs.
Tempurpedic also doesn’t disclose the specific type or quality of the Tempur float material in their weightless line so your testing for PPP would be the best way to determine it’s suitability but there would be some question about it’s quality and durability as well although I believe it’s high resilience polyfoam and a good quality material. Without the knowing the specifics you are only guessing about what they might be using and I would tend to avoid any mattress where there are too many unknowns in terms of the density and durability of the materials. Without this information there really is no way to make any meaningful assessments about the quality of the materials in a mattress or the quality and durabilty of the mattress itself or make meaningful comparisons with other mattresses.
As you can see from the first part of this post and mattress firmness/comfort levels in post #2 here … there are just too many unknowns and variables for anyone to recommend a specific mattress for anyone else based on “theory at a distance”. I can certainly help with how to choose but the specifics of what to choose is up to each person’s personal value equation and all the objective, subjective, and intangible parts of a mattress purchase (or in your case an exchange) that are most important to them.
Phoenix