Is it common that stomach and back sleepers over the age of 40 want, desire - and even need - a more firm, supportive mattress - even if they’ve had no “real” back or alignment problems?
It seems that during my 40s, I’ve wanted to go firmer and firmer for my stomach sleeping (while using a fairly thin topper as a comfort layer.)
I also want to point out that I am finding there is a big difference between “supportive/firm” and “hard” or “matted”.
The former is what is working for me while the latter doesn’t always hold up my back.
A firm pocket coil mattress with my own topper seems to be just right for me these days.
Hi LookingNow,
Stomach sleeping is the most risky of all sleeping positions because of the tendency of the pelvis to sink down too far and tilt which can lead to sleeping in a swayback position (aka hyperlordosis) with the lumbar spine hyperextended beyond it’s neutral curvature. This will often lead to lower back discomfort and pain. This is the reason that stomach sleepers generally need thinner/firmer comfort layers so that there is “just enough” softness on top of the mattress to sleep comfortably and relieve any pressure points while keeping you closer to the firmer transition and support layers underneath the comfort layers which can stop the pelvis from sinking down too far.
This would be true for any age but outside of a few people I know where aging doesn’t seem to have any effect (and unfortunately I’m not one of them), as age begins to creep up on us we tend to become less flexible and things that would have had little effect when we are younger and “invulnerable” will have a bigger effect on us.
There is a little more generic information about the needs of the different sleeping positions here.
Your situation is very “normal”.
Phoenix
Thanks, Phoenix.
Hope you’re enjoying the springtime
Hi LookingNow,
I am … and today there is some “real” sunshine instead or “liquid” sunshine in the pacific northwest 
Phoenix