Hi Chirurgeon,
It could actually be a combination of both because a mattress needs to “allow” some parts or your body to sink in enough (such as the shoulders when you are on your side) and at the same time “stop” the heavier parts of the body from sinking down too deeply (such as your pelvis when you are on your back).
The most effective way to really know is to go by the specific symptoms that you are experiencing.
TheCool Luxe would normally be considered to be a soft mattress so the odds are good that the mattress is not too firm although each person is different and softness and firmness and how a mattress interacts with different people is relative to each person. When you experience pressure issues under your shoulders it would most often be from a mattress cover or bedding that is preventing the foam from compressing enough to “allow” your shoulders to sink in as much as they need to, a pillow issue (a new mattress often needs a new pillow to go with it to better support the weight of your head and neck and keep them in alignment on a new sleeping surface), a matter of the initial break in or adjustment period that can sometimes take a little longer to soften the foam under the shoulders which are lighter than the pelvic zone of the body, or it could also be the design of the mattress as it relates to your specific body type. In other words your shoulders are probably bearing too much weight and this needs to be reduced or re-distributed to other parts of the body. Typically this indicates the need for “softer” or “more sinking in” under the shoulders.
When you experience back issues when you wake up … the most common cause (but not the only cause) is that your pelvis is sinking down too far and affecting the natural curvature of the spine. This could be connected to a foundation which isn’t supportive enough under the middle part of your body, to the firmness of the support layers, or to the thickness and softness of the comfort layers. Typically this indicates the need for “firmer” or “less sinking down” under your pelvis.
Issues with waking up during the night could be related to either pressure or support issues causing discomfort or they could have nothing to do with the mattress itself and just be the result of many other factors that can affect the quality of sleep (food and diet, medications, sleep routine, physiology, overall health and wellness, physical condition, sleeping temperature, breathing, environment in terms of light and sound, phychological issues or stress, freedom of movement on the mattress, and many other factors).
This is why it can be limiting to think only in terms of softer or firmer because different parts of your body may have different needs or requirements and the balance between softness and firmness is the key rather than just one or the other. This is the basis of all mattress design and theory so that people with different body types and sleeping styles can have good pressure relief and stay in good alignment in all their sleeping positions over the course of the night. In other words … it seems your mattress at least for now may be too firm under your shoulders when you sleep on your side and too soft under your pelvis when you are on your back.
Overall though … I would first eliminate all the other possible causes outlined in this post and in the post I linked in your other thread (in post #2 here) so that you are dealing with fewer variables that can affect how you sleep on your mattress, talk to Brooklyn Bedding in more detail about any suggestions they may have and about your options (they have good experience in helping people with their mattresses), and then of course decide on what your best course of action may be. The ideal of course is to fine tune the mattress you have so that to the degree possible for any mattress it “matches” your specific needs and preferences in terms of PPP.
Phoenix