Mattress Underground is superb! Helping us narrow our choice toward a mattress purchase.
Sweating is a particular problem with us. Do you have any wicking/keeping-dry comparisons between synthetic covers, specifically the Tuft & Needle cover (“95% Rayon surface content; overall composition 50% rayon, 50% polyester”, which do such a good job of it in underclothes and socks) and a bamboo cover like the one used by DreamFoam?
Or should we assume that any moisture control should be accomplished by whatever mattress pad and sheets are put over it, making the mattress cover irrelevant?
Hi greencreative,
Most of the moisture wicking and humidity control will come from the top layers of your sleeping system which includes your bedclothes, your sheets and bedding, and your mattress protector but the mattress cover and any quilting materials will also play a role as well and the ventilation and airflow under these layers will also play a role because without airflow and a pathway for air to reach the outside environment or be transported away from the skin the moisture or higher humidity levels can build up against the skin and increase sleeping temperature (which is why some types of memory foam sleep warmer because they allow less airflow for the moisture laden air to transport heat and moisture away from the body).
There is more about the many variables that can affect temperature and humidity and the microclimate of a mattress in post #2 here and the posts it links to (including post #29 here about moisture wicking).
There is also much more information about the pros and cons of different types of fibers and fabrics and their temperature and moisture regulating properties in post #7 here about sheets and bedding.
In very general terms … natural fibers (such as wool, cotton, and flax linen) and semi-synthetic fibers (such as bamboo or other types of viscose/rayon fabrics) will absorb moisture more effectively into the fiber itself to keep it away from the skin while synthetic fibers can only absorb moisture into the spaces in between the fibers but not into the fiber itself which can result in higher moisture and humidity levels against the skin.
Higher humidity levels against the skin can reduce the cooling effect of evaporation (just like higher humidity levels can make the perceived outside temperature seem hotter than it really is) so it can result in higher sleeping temperatures and more perspiration. Blends of natural and synthetic fibers can also be an effective choice if the natural fiber content is relatively high but again in very general terms synthetic fabrics are generally less temperature regulating than natural fabrics.
These are difficult questions to answer in any quantifiable terms though because there are so many variables involved in the combined effect of the fabric layers that are over the mattress along with the airflow (or lack of airflow) in the layers underneath them which can all have an effect on regulating temperature and humidity in a sleeping system but your bedclothes, your sheets, and your mattress protector (or mattress pad if you use one) can have a bigger effect than the mattress cover itself because they are closer to your skin.
Phoenix