Hi hester,
I’m mostly tummy but sometimes a side sleeper.
I read here that for my size / weight i should sleep on 6-7" of latex. Seems too much. ( I’m 5’3" ~130)
I have a combination shikibuton with latex and wool. It’s 2" of Dunlop (ILD 34-38) latex enclosed in wool … they say 1/2" but the total height is more like 4" and not the advertised 3". On top of that I have a 1" firm latex topper from SoL. It took me a while to figure out what to put on top as soft was suggested but the soft gave me back pain.
Every individual layer and component in a mattress (including the cover, FR barrier, any quilting material, and any layering you are using) will affect the feel and response of every other layer and component both above and below it and the mattress “as a whole” … thinner mattresses are not an exception. The futons used in Japan are overwhelmingly 3"-4" in thickness, although sometimes they can be found in 5". These go directly on the floor and then are stored away during the day. When you have the material that feels good to you, appropriate layer thickness, density, and a good base/support for your BMI, preferences, and sleep style, you’d be surprised at what kinds of setups can be comfortable!
Since you are currently sleeping primarily prone you’d need a firmer sleeping surface to keep your spine from getting hyperextended in a swayback position. I am guessing that this is what caused your back pains when you used the softer latex topper. As you are also a lower BMI sleeper you would not need as much thickness to get both pressure point relief and spinal support.
So I have
1" coir pad, ~3/4" wool, 2" latex , ~3/4" wool, 1" latex, 3/4 - 1" mattress cover of wool and cotton. So, minus coir pad, a total of about 5 1/2" of bedding, of which 3" is latex.
It’s actually comfortable. How do i know if it is or is not enough?
Shikibuton is a successful company in Japan that expanded its brand to North America. It is true that their Japanese-style futons that are 3-5" in thickness (depending on the model) are generally considered quite thin to get enough “comfort” by North American standards but this perception varies from person to person. The futon seems to be well-made, lightweight, compact, and easy to store, and it uses quality natural materials. This Asian popular style may be very well suited for lightweight-prone sleepers.
For your weight and sleeping position, the build and combination of materials in your final setup look good and do not raise any red flags. There is no right or wrong when it comes to personal needs and preferences As you already determined, the only way to know for sure if you have “enough” thickness is to sleep-test the bed.
It looks like with a little bit of twitching you dialed in on the right combination of materials and firmness. Like with any mattress purchase … the only way to know how well you will sleep on a particular build compared to other combinations of materials and thicknesses is always based on your careful testing as you are the only one that feels what you feel on the mattress. Different people can have very different experiences on the same mattress or materials.
I’d make a quick inquiry to Shikibutons customer service to find out if they have some advice on maintenance tips and how their futons may act in combination with the 2 latex layers (They know their product better than anyone else)
All in all, it looks to me like you have a winner!
Phoenix