The topic is pretty complex because there are a lot of factors that can affect one's sleep.
Does natural latex sleep hot?We get this question a lot. We like to tell people, "it's not the mattress that's hot. It's us". Our bodies radiate heat and it's trapped by the materials in our bed. A latex mattress is theoretically cooler than memory foam, but you're still sleeping on 9" of foam. When people report that they are hot sleepers -- as opposed to just being too warm in bed -- we suggest an innerspring mattress may be better. In those instances no mattress will help. The person will be hot regardless of the mattress. The conundrum is you're not sure if it's you or the mattress. It can be both and.
Keep in mind that latex will sleep cooler than memory foam, but it won't be as cool as an innerspring with minimal padding. There is more empty space in an innerspring thus more ventilation and a somewhat cooler sleep. Although an innerspring with a lot of foam over the spring unit can sleep just as hot as a latex or memory foam mattress.
As for sleeping warm, the more one sinks into the mattress, the higher chance they have of being warmer. This is what can make memory foam sleep "hot". It's experienced less often with a very firm latex mattress that's buoyant, keeping the sleeper on top of the mattress. Basically, the softer the mattress, the warmer it will sleep because you are more enveloped in the materials.
Keep in mind that the top of bed is an often overlooked part of the equation as to why people sleep hot in bed. There are a few factors contributing to warmth beyond the mattress. For example, the duvet or comforter can be contributing to sleeping hot. You have layers of fabric and fibers in the duvet cover that can help retain body heat. Another way to think of it is in colder weather, we put layers on to keep warm. An ultra lightweight comforter works best. In my experience, a duvet is a major contributor to making a mattress sleep warm. Anecdotally, in my guest bedroom I have a Spindle with a duvet comforter, and it sleeps significantly warmer than the Spindle mattress in my room which is a thin quilted cotton comforter. The duvet traps the heat and I wake up sweating, but in my room I don't experience this at all.
There are a lot of factors that go into why a mattress sleeps warm. On an identical mattress with the same sheets, blanket, etc, two people can have two totally different experiences where one says it sleeps hot and another says it sleeps cold. Some people just sleep hot all the time, whereas others are always cold and need a heating blanket. Everyone is different and unfortunately there isn't a simple yes or no answer.
It's estimated one's mattress accounts for about 40% of our sleep experience. Temperature in bed can also be affected by
sheets -- textiles such as tencel, microfiber, linen, outlast, cool max and others are being used to help wick moisture away from the body and to dissipate heat...some brand names include: Sheex, Sleep Philosophy, and others. This article from the Spruce and this one from NY Magazine may also help.
blankets + duvets -- using a duvet will trap body heat more effectively than only a blanket. changing up what's on top of your mattress can help
pajamas -- hi-tech materials from athletics and hiking such as cool-core, dri-fit,nylon/lycra micro-mesh, are all great at wicking moisture [we all sweat at night]. They can be also be very effective in helping to dissipate heat.
insufficient hydration; alcohol intake; sleep hygiene; dreams; humidity in the room; ambient temperature and more.
It's not just about the mattress. Sometimes a few simple adjustments, or a combination of a variety of changes, can make a big difference.
There are a lot of factors beyond the mattress, however, that contribute to bedtime temperatures. These may include: ambient room temperature, humidity within the room; bedding; pajamas; diet, alcohol, hydration; bed partners; sleep hygiene; and much much more.
Addressing some of these will make some improvements, but won't totally eliminate the issue. Mattress related factors we recommend:
Mattress protector. Today's modern waterproof protectors are a great choice for most people but they are less breathable than say a washable wool mattress protector. For those who experience excessive sweating, other options may need to be explored. We have some wool pads listed on our website, which we try to keep current.
The best solution we've seen is the ChiliPad. Just as you might use a heating pad to pre-warm your bed, a ChiliPad uses flowing water to keep your sleeping surface cool. These are not cheap in any meaning of the word, and it could be a good investment.
Sheets and bedding made with a phase-change material like Outlast can also keep you cooler. Unfortunately, we're not sufficiently experienced with these products to give you a worthwhile recommendation.
Duvets or lofty down comforters will also trap in body heat. An ultra lightweight comforter works best. Transitioning from cotton pajamas to heat/moisture wicking clothing can also make a big difference.
There is no science to this and the list above is far from exhaustive. Most people use a combination of approaches that make most sense to them. We're all very different and the solutions we develop are likewise just as unique.
