Hi JDMWDC,
What’s the rule with regard to “sink in” of the memory foam?
As with most things concerning mattresses … the “rules” are always about how a mattress performs not about which materials or design is “better or worse” because this depends on the person. Better and worse is always measured by how a specific mattress interacts with a specific person. Everything comes down to which mattress provides you with the best possible spinal alignment in all your sleeping positions, the best possible pressure relief in your most pressure prone positions, and has the combination of other qualities that you most prefer (ventilation and temperature regulation, motion isolation, responsiveness and resiliency, freedom or restriction of movement, feeling more “in” the mattress or “on” the mattress and many others) along with the durability of materials that will ensure that the properties of the mattress stay closer to their original specifications for a longer time than lower quality materials and the tradeoff between cost and higher performance and more durable materials and designs.
Every type of material including memory foam has many different versions or varieties that each have their own unique and different properties (you can read about some of the differences between different types of memory foam in post #9 here and post #8 here). I can only speak to the quality and value of a mattress (which has nothing to do with how it may feel and perform for a specific person) and because I have never slept on their mattresses I have no personal experience with how they feel for me (and my specific body type and sleeping style) or how they may feel for someone else. The manufacturers themselves are always the best source and are in the best position to describe how their memory foam feels and performs or how one of their mattresses as a whole may compare to others that either you or they they are familiar with.
Each different mattress design and the thickness and types of layering and other components will also make a significant difference in terms of how a mattress interacts with different types of people with different body types and sleeping styles. Heavier people, people who have a narrower waist and either wider shoulders or hips, or people who are side sleepers will sink into the top layers more deeply than lighter people or those who sleep in flatter positions (back and stomach). The middle layer is more of a transition layer and has a more “dual” role in a mattress because it “helps” with pressure relief, primary support, and secondary support and is a big part of how a mattress adapts to different people and different sleeping positions. Because latex is so adaptable and has a wider range of response between soft with initial compression where it needs to be and firmer where it needs to be with deeper compression … it is particularly useful in transition layers. In addition to this it is also a very durable material and will keep its properties for a long time and for those people who sink into the mattress past the top layer it’s durability can also play an important role in the durability of the mattress as a whole.
The middle transition layer will also lend its properties to the layers above it. If the transition layer is more resilient (and latex has much higher resilience than memory foam which has very little at all) then depending on how thick the layer above it is and on how much someone sinks into the mattress … it will “modify” the properties of the layer above it to different degrees. If the transition layer is latex and the top layer is thin enough for a particular person to “feel” the deeper layers … then the “feel” of the mattress will be more resilient and responsive to movement. If the transition layer is memory foam … then the “feel” of the mattress will be mush less resilient and responsive to movement. Memory foam tends to “restrict” movement because it absorbs energy and latex tends to “allow” movement because it is highly resilient and returns energy to the body when you move. The closer to the top of a mattress a particular layer is the more it will contribute to the overall feel and response of the mattress. “Comfort” which is what most people feel when they first lie on a mattress and is most dependent on the upper layers. Support and sleeping with your spine in a neutral alignment in all your sleeping positions over the course of the night is what most people will “feel” when they wake up in the morning (with or without stiffness and back discomfort or pain).
As you can see in post #4 here (and the posts it links to) which talks about all the factors involved in durability … this is correct and the layers above another layer will improve the durability of the layers below it.
I am also one of those who likes the combination of memory foam and latex in the comfort layers (although I prefer all latex even more) and I also prefer latex over memory foam (with a thin layer of latex over a thin layer of memory foam so that they “modify” each other more effectively than a thicker top layer would) because I prefer a more resilient sleeping surface that “allows” for more free movement on a mattress. As you mentioned this is the other way around than is most commonly found. One advantage of the Aloe Adele for example is that you can reverse the top two layers and put latex over the memory foam.
I tend to approach things from the other direction. As you can see in post #2 here which compares a latex hybrid mattress to an all latex mattress … there are clear differences between their performance levels and then the question becomes whether the higher cost of a higher performance mattress that has more costly and higher performance materials is comfortably in your budget range. Not everyone can afford the highest quality mattress available even though they would be “worth it” in terms of quality, performance, and durability. The other advantage of a mattress like the Aloe Alexis (or Aloe Adele) is that it allows you to “fine tune” both the comfort layer and the middle transition layer so it is a much more flexible design in terms of customizing a mattress to your specific needs and preferences either before or after a purchase. A forum search on aloe alexis bamboo bliss (you can just click this) will also bring up more posts with more information about how they may compare.
These are all decisions that need to be answered on an individual basis based on your own unique personal value equation and what is most important to you because nobody else can really tell you which would be better or worse or match your personal criteria in a mattress better than you.
Phoenix