Thanks for the update! I am glad you’re feeling more confident.
It is promising that you’re starting to see an improvement sleeping on the coils without the latex layer and it is indeed a useful data point. In this setup, your spring unit is now playing a dual role … that of support and comfort. Because of the missing comfort layers, you have firmer support and some inadequate comfort coming from the spring unit itself. This is not ideal and it is not advisable that you try to get your support comfort needs from this layer only, but what this experiment tells you is that you probably need a firmer support layer in combination with an appropriate comfort layer on top. For this, you may wish to revisit the The basic functions of a mattress article for clarifying these concepts.
In your last post, you introduced some more variables such as your mid-back muscle pains which may have several reasons including using an inappropriate pillow (see my comments below), also the side sleeping, so I’d certainly monitor the type of pains you are experiencing and the positions they are associated with…
Thanks for the clarification, this means that you need to take into account that side sleepers generally need a bit more pressure point relief on the surface to accommodate the wider dimensional variances between the shoulders, hips, and waist. There’s a bit more about different sleeping positions here . The key when sleeping upon your side is to make sure that you are not sinking in too deeply with an excessive lateral curvature. This article speaks to this in a bit more detail.
Most side sleepers will fall in the range of needing from 2" -4" in their comfort layer. Without an appropriate comfort layer, a side sleeper will end up with pressure points during the course of the night and could have symptoms of numbness, soreness, localized redness, or end up tossing and turning all night as your body tries to relieve the pressure. That’s just a little more information to consider in your testing.
Thanks for clarifying where you are experiencing your pain. In the case of the mid or upper body, good horizontal alignment is important but lateral (side to side) alignment is also important. For example, if you bend your head and neck forward towards your stomach (for back sleepers) or your head and neck backward and twisting for prone sleepers then it can bend the upper spine and create tension and pain in the mid and upper back. It can also happen if the upper layers are too thick and soft.
A suitable pillow is an essential part of good alignment for the head and neck and upper body because the gap between the head and the mattress and the curve of the cervical spine needs to be supported just like all other parts of the spine. In your case, because you are sleeping prone the use of a pillow will exacerbate the cervical curvature and twist the spine in that area. Like mattresses … there are certain “needs” that depend on body type and sleeping positions. There is more about choosing pillows in the pillow thread here and the other topics and sources of information that it links to that may be helpful.
In the same way … if you push your arms and shoulders forward into a forward slouched position then it can also create tension and soreness in your mid or upper back. This can come from a mattress that has comfort layers that are too thick and/or soft and allows your torso to sink in a little too far but “holds up” the lighter shoulders (pushing them forward). In both cases, your muscles will be tense and working throughout the night to maintain alignment.
You can read more about what tends to cause back pain in post #2 here.
I’d assess your pillow as well and after a few more days of experiments, I’d make a clear summary of your findings before moving forward with any decisions or purchases.
Looking forward to additional updates!