r/mattress FAQ says all the 'cooling' technology is mostly a marketing gimmick. For those of us who sleep hot, it seems like there isn’t much to actually consider here—just control the bedroom and bedding temperature better?
Fair question and we wanted to share our take as people who actually make mattresses.
Yes, the major factor is bedroom temperature and humidity in the room. Beyond that, there are a lot of other factors. The type of mattress construction does impact it, and airflow matters.
The cooling technology is a gimmick and not a gimmick. Phase change materials do work, but the effects may only last 10 minutes to maybe an hour. Gel foam is a gimmick and doesn't help with cooling.
As an example of the mattress constructions impact on temperature, a memory foam mattress design with a smooth flat quilted cover with memory foam as the top layer and a foam base that is soft and above, say, 4 pounds per cubic foot is going to be the mattress that sleeps the hottest. Why? Because of the design, you are going to be more enveloped in the materials as you sink and get wrapped in the materials. Think being wrapped in a blanket tightly versus loose with air flowing around you. Being wrapped tighter will keep you warmer, just as the memory foam is doing. Since it is 4-pound memory foam, the material is more dense so less of an opportunity to disperse heat. People will read this and think then they should never buy this mattress. To the contrary, if you love this mattress and it feels great and only sleeps hot, do other things to help mitigate it. The mattress takes all the blame and is viewed as the solution to everything and the problem for everything. Why get a mattress that sleeps cool and then is uncomfortable?
Keep in mind that everyone is different, so these are generalities that applies to a larger segment say 75% of people so you will find contradictory information as 25% (just a number off the top of the head) to a lot of the information provided anywhere.
What’s the coolest sleeping mattress on the market? Probably an open coil mattress with no insulator pad (which is dense and cuts down on airflow) with maybe ½” or 1” of foam in a 1 or 1.2-pound foam. Innersprings have more airflow. But it might not be the most comfortable mattress for most people.
An innerspring does provide better breathability, but if you stack 8" of foam above it, that negates the breathability. An innerspring with 0.5" of foam above it will sleep cooler than one with 3".
Also, the density of the foam matters. Lower-density foams like 1.2-pound foam will sleep cooler than 1.8 or 2-pound foam because they are less dense with better airflow.
Don’t forget, the firmer the mattress, the cooler it will sleep. Why? Because you are less enveloped in the mattress and there is more airflow around your body to keep you cooler. But that doesn’t mean you should buy a firm mattress if it is not comfortable.
With any mattress, there are always tradeoffs, and you need to decide what matters most to you: comfort, support, durability, or temperature regulation.
I’ll stop on the mattresses—I probably missed a couple of things—but this provides a good start. Let’s go beyond the mattress.
What you eat and drink before bed can impact how warm you sleep. For example, alcohol's ability to alter the body's heat regulation mechanisms significantly contributes to the occurrence of night sweats.
The type of mattress protector, your sheets, and blankets above you impact how warm you sleep. For example, I bought a new comforter. My ten-year-old mattress never slept warm and now I wake up consistently sweating. Lighter weight materials work better, and fewer materials above you impact the ability for heat to dissipate.
Cotton might not be the best option, as it retains moisture more than synthetics. Look at most workout materials—they’re synthetic. Think about working out in a 100% cotton t-shirt vs. a Nike Dri-FIT or other similar materials.
One example of top-of-bed impact on sleeping warm is the blankets. A lot of people use duvets, which is layering more materials above you that trap heat. Think of it this way: if you wear one t-shirt to work out or three t-shirts, which one is going to be warmer? Obviously, wearing three shirts will be. A duvet usually has an insert and two layers of fabric. Even without the insert, there are two layers of fabric above you with a duvet plus your sheets to help trap your body heat.
Some people have two sets of bedding depending on the season or temperature.
What you wear to bed matters too.
If you have tried all of these and nothing works, consider getting a device like BedJet, ChiliPad, Eight Pod, or SmartDuvet by RizeHome.
Bottom line: it’s not just the mattress. You have to look at everything holistically.
