Question about memory foam and heat

[phoenix]

Hi Jpeepot,

Welcome to the Mattress Forum!

Hi Mattress Underground! First of all, thanks for a great site. Shopping for a mattress is a complicated process and you guys provide a lot of terrific and helpful information.

Thank you!

So despite having read a lot of info on this site and on other sites during my mattress search, I ended up recently making a bad purchasing decision. I bought an Atlas firm from Bloomingdale’s Asteria line, and not only is it way too firm… it doesn’t conform well to my body… with a somewhat deep back arch and a rather pronounced “seat”

While Bloomingdale’s doesn’t list the complete specifications of this mattress on their site, it certainly is listed as a “firm” mattress, and appropriate for a stomach sleeper. With the limited specifications they provide, I would expect this to be a quite firm bed, which obviously is a comfort issue (part of your PPP) for you, as opposed to any defect in the product. I’m curious to know if you had the chance to try it in a showroom or if you ordered it without any real testing, as the description of the product online and your “body shape” as provided wouldn’t necessarily align with this type of mattress.

but it’s also hot as hell, I’m guessing because it’s predominantly a foam-based mattress.

The mattress looks to be a more normal typical innerspring design. It’s only 11" in thickness, and it uses an innerspring unit, so it’s not mostly made of foam. There are two layers of foam in the quilt (they don’t list thicknesses or type of foam, but I would guess some sort of polyfoam), and on top of this is a silk/wool blend layer. They don’t list the percentages of these fibers (often it’s minimal), but this would usually assist with airflow and temperature regulation. The deeper layer is cotton. They don’t provide how thick this layer is, but generally this would be breathable as well, unless it was an incredibly dense pre-compressed layer. It’s also deeper in the mattress, so it would have less of an effect in your surface temperature than the upper layers of foam. The mattress is adjustable bed compatible, which means that the edge reinforcement will either have holes placed in it at strategic locations or it will be slit at certain points, which will also assist a bit with air movement. The foundation it a slat network, so there is airflow there as well.

I can’t tell how closely stitched the quilt panel is made, so if it is letting you sink in a bit there could be a bit less surface area exposed for heat exchange. In very general terms … the materials, layers, and components of a sleeping system that are closer to your skin will have a bigger effect on airflow, moisture transport, and temperature regulation than materials, layers, and components that are further away from your skin and softer mattresses or foam toppers will tend to be more “insulating” and for some people can sleep warmer than firmer versions of the same material.

There are so many variables involved including the type of mattress protector and the sheets and bedding that you use (which in many cases can have just as significant an effect on sleeping temperature as the type of foam in a mattress) and on where you are in the “oven to iceberg” range and because there is no standardized testing for temperature regulation with different combinations of materials … there is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here. Please read through that post – it’s very useful.

I’m curious as to what you’re using for a mattress pad/protector, sheets and comforter, as well as the room temperature. Your top-of-bed items can have a dramatic impact upon your sleeping temperature.

Now my qualms are two-fold. The first is do I have any business looking at a mattress that has two inches of memory foam in the comfort layer given my problem with the Asteria sleeping hot and my general inability to fall asleep and keep asleep when I’m too warm?

All foams are insulators, and the closer to your body and the more you sink in, the more they will tend to insulate. Memory foam tends to be the most insulating and least breathable (“cooling gels” tend to be a bit temporary and not last through the night in their ability to eliminate this phenomena). Polyfoam will tend to be the next most breathable, and then Dunlop latex, and finally Talalay latex. Of course there are variations in the densities of these foams that can have an effect on air movement, but this is a good guideline.

If you’re sleeping hot on the Atlas, I’d personally have more concerns moving to the memory foam mattress you mentioned. While it is an innerspring and certainly will have better airflow than a “traditional” memory foam mattress with a polyfoam core, you’ll still be sinking in deeper than on the Atlas and you’ll be surrounded by a more insulating foam. At least, that’s my “theory at a distance.” In very general terms, it’s really not possible for me to quantify the sleeping temperature of any person with any real accuracy because there are so many variables involved.

The second qualm is about something the salesperson said. She commented that as a predominantly back sleeper (I’m probably 60-40 back-stomach) the memory foam might feel good initially but in the morning leave me with a back ache because it wouldn’t give me the support that I need, which latex would (a major component in all their more expensive mattresses wink wink). In the store I felt completely aligned, and latex feels too firm for me; I don’t like how it presses up against my back. So, is the generalization the salesperson made credible at all? Or is it really an individual thing that can’t be generalized?

These are all very general statements about which I really can’t provide an accurate answer. Latex will certainly be more breathable than memory foam, but it would be just one layer of any particular mattress. If the mattress you tried with latex felt like it pressed up on your too much, perhaps the latex was too firm or it felt that way in combination with other materials within a mattress. Latex certainly has a very supportive feel, but there are softer types of latex that are very conforming. Perhaps you truly do like to be “in” a mattress rather than “on”, in which case you make enjoy memory foam, but you have to manage your expectations with the pros and cons of memory foam and temperature regulation.

Regarding cooling memory foam claims, you can read more about phase change materials in post #9 here and at the end of post #4 here) and you can read more about the various different types of gel foams in post #2 here. In general terms gel foams will tend to have a temporary effect on temperature while you are first going to sleep until temperatures equalize but have less effect on temperature regulation throughout the course of the night.

I guess the first thing you need to do is find out what Bloomingdale’s will do for you, and then I would go back and re-read the Mattress Shopping Tutorial and begin again in your mattress search.

Let us know what happens.

Phoenix