What Makes a Mattress Breathable?

If you have ever woken up hot in the night and blamed your mattress, you were probably right. But not for the reasons the mattress industry would have you believe. "Cooling mattress" is one of the most overused and least honest phrases in mattress marketing. Here is what actually determines whether a mattress sleeps warm or cool — and what you can actually do about it.

In this guide

Breathable vs insulating (the only two things a mattress can be)
The honest truth about "cooling" mattresses (what the marketing does not say)
What each material actually does (coils, foam, latex)
The foam question (can you avoid it? should you?)
What this means when you are buying
Frequently asked questions

Breathable vs Insulating: The Only Two Things a Mattress Can Be

A mattress is either breathable or insulating. That is the whole spectrum. A breathable mattress allows body heat to move away from you through the materials and into the surrounding air. An insulating mattress traps body heat close to you, which makes you warmer as the night goes on.

Every material in a mattress sits somewhere on that spectrum. The construction of your mattress, which materials are used, how much of each, and in what order, determines where the whole package lands. There is no such thing as a mattress that actively cools you. Unless you are plugging it into the wall, it is not cooling anything. The best it can do is get out of the way of your body's natural heat management.

The simple version: Your body generates heat. A good mattress lets that heat move away from you. A bad one traps it. Breathability is about how well the materials allow that heat to escape, not about any active cooling technology.

The Honest Truth About "Cooling" Mattresses

Walk into any mattress store or browse any mattress website and you will see the word "cooling" everywhere. Cooling gel foam. Cooling covers. Phase-change materials. Arctic this, cryo that. Most of it is marketing layered on top of a basic principle that the industry does not want to state plainly: foam, by its nature, is not very breathable.

Gel foam is regular foam with gel beads or gel swirls mixed in. The gel does absorb heat initially, which is why gel foam mattresses often feel cool to the touch when you first lie down. But gel has a limited capacity to absorb heat. It reaches equilibrium relatively quickly, and once it does, it behaves like regular foam. The cool-to-touch feeling does not last through the night for most people.

Phase-change materials work on a similar principle: they absorb heat up to a threshold and then stop. Covers treated with phase-change coatings feel genuinely cool when you first get into bed, and that is a real effect. But for a hot sleeper who generates consistent heat through the night, the phase-change material has often done its job within the first hour.

Worth knowing: If a mattress review or a mattress brand claims a foam mattress is "cooling," what they usually mean is that it is slightly less warm than a comparable foam mattress without the cooling treatment. That is a meaningful difference, but it is not the same as a mattress that actually keeps you cool. The benchmark should be a well-built hybrid, not another foam mattress.

What Each Material Actually Does

Pocket Coils

Most Breathable

Steel coils are durable, supportive, and breathable. The cavity inside a pocket coil mattress allows air to circulate freely through the mattress, which means body heat can move away from you rather than being trapped close to the surface. The coil system does the bulk of the work when it comes to allowing your body heat to escape. This is the single biggest reason well-built hybrids sleep cooler than all-foam mattresses.

Natural Latex

Best Foam-Type Option

Natural latex is the most breathable foam-type material available. It has an open-cell structure that allows more airflow than synthetic foam, and it does not retain heat the way memory foam does. It also responds quickly to movement, so it does not have the "hugging" quality of memory foam that traps heat around the body. For hot sleepers who need foam in their mattress (and everyone does, more on that below) latex is the material that causes the least thermal disruption.

Open-Cell Foam

Acceptable

High-quality open-cell foam allows more airflow than standard polyfoam. It is not as breathable as latex or a coil cavity, but it is a reasonable middle ground. The quality of the foam matters significantly here. Low-density foam tends to be denser and less breathable than high-density open-cell foam, despite what you might expect from the name.

Memory Foam

Most Insulating

Memory foam is the least breathable common mattress material. Its viscoelastic properties, the slow response and body-conforming hug, are also what make it retain heat. The close contact with the body's surface limits the air gap that allows heat to dissipate. Memory foam beds are generally the warmest type of mattress. Gel treatments help at first, but the underlying material is still memory foam.

The Foam Question

If foam is the problem, the obvious question is: can you just avoid it?

No. And you would not want to if you could.

Steel coils are durable, supportive, and breathable, but they are not comfortable on their own. Foam is what makes a mattress comfortable to sleep on. Without a foam comfort layer above the coils, you would feel the springs directly, and the surface would be far too firm and uneven for most people. Foam is not the enemy of breathability. Too much foam, or the wrong kind of foam, is.

The relationship between coils and foam in a well-built hybrid is a balance. The coil system handles the bulk of support and breathability. The foam layers above the coils handle pressure relief and surface comfort. The coil cavity is doing the work of moving heat away from you; the foam layers are a necessary interface between your body and that coil system. The goal is to use enough high-quality foam to make the mattress comfortable, without so much that the foam's insulating properties start to dominate.

Can you escape foam? No. Do you need foam? Yes. Is too much foam good? Generally no.

That is the whole equation. A well-built hybrid uses quality foam in the right quantity above a pocket coil base. The coils breathe; the foam comforts. Together they are a better solution than either material alone.

What This Means When You Are Buying

When you are comparing mattresses and temperature is a concern, ignore the cooling marketing and look at the construction instead. A few things that actually matter:

Is it a hybrid or all-foam?

A hybrid with a pocket coil base will almost always sleep cooler than an all-foam mattress at the same price point. The coil cavity is the most effective breathability mechanism in a mattress, and no foam treatment fully replicates it. If you run warm, start with hybrids.

What kind of foam is in the comfort layers?

Natural latex is the best choice for hot sleepers who need a softer comfort layer. Open-cell foam is a reasonable second. Memory foam is the warmest option. This is why Dozy's Richmond and Forest Hill, which use GOLS-certified Talalay latex in the comfort layers, are the right recommendation for customers who specifically flag temperature as a concern.

How much foam is there?

A thicker foam comfort layer insulates more than a thinner one, regardless of the foam type. A mattress with 4 inches of foam above the coils will sleep warmer than an otherwise identical mattress with 2 inches. This is one area where mattress height can be a useful proxy. An extremely thick mattress often has more foam above the coil base, which can affect breathability. Thicker is not always better.

What is the cover made of?

The fabric cover is in direct contact with your body and has a real effect on surface temperature. Natural fibres like cotton, wool, and certain blends are more breathable than synthetic covers. Dozy uses OEKO-TEX certified fabric covers across the lineup. A cover treated with phase-change material will feel noticeably cool when you first get in, which some people value even if the effect does not last the full night.

Frequently Asked Questions

Do cooling mattresses actually work?

Not in the way the marketing implies. A mattress cannot actively cool you; it has no mechanism to remove heat, only to allow it to escape or trap it. What are marketed as "cooling" mattresses are typically foam mattresses with gel treatments or phase-change covers that reduce heat buildup compared to standard foam. The effect is real but limited, and it does not compare to the breathability of a well-built hybrid with a pocket coil base and quality foam comfort layers.

Why does memory foam sleep hot?

Memory foam's viscoelastic properties, the slow response and body-conforming quality that makes it feel comfortable, also mean it retains heat. The foam hugs closely around the body's surface, which limits the air gap that allows heat to dissipate. Gel treatments help initially by absorbing heat, but the underlying material is still memory foam, and the gel reaches its capacity relatively quickly. For hot sleepers, a hybrid with latex or open-cell foam comfort layers is a better long-term solution than memory foam with cooling treatments.

Is latex cooler than memory foam?

Yes, consistently. Natural latex has an open-cell structure that allows more airflow than memory foam, and it does not have the slow-response body-hugging quality that traps heat. It also tends to sleep cooler than synthetic foams. For hot sleepers who want a foam comfort layer, latex, particularly Talalay latex which has an even more open cell structure than Dunlop, is the most breathable option available. Dozy's Richmond uses GOLS-certified Talalay latex for exactly this reason.

Does a thicker mattress sleep hotter?

Often yes, but it depends on what the thickness is made of. A thicker foam comfort layer above the coil base insulates more than a thinner one. A mattress that is tall because it has a larger coil base rather than more foam is not necessarily warmer. When comparing mattresses, it is more useful to ask how much foam is above the coil layer than to look at total height. A 14-inch mattress with 3 inches of foam above the coils may sleep cooler than a 12-inch mattress with 5 inches of foam above the coils.

What is the most breathable mattress Dozy makes?

The Forest Hill and the Richmond are both hybrids with GOLS-certified Talalay latex comfort layers, which makes them the most breathable options in the Dozy lineup. The latex layer is naturally open-cell and temperature-neutral, and the pocket coil base allows airflow through the mattress. If temperature is your primary concern, these are the mattresses to try first. Come in at 290 Queen St W and we can walk you through both.

Does the mattress cover make a difference?

Yes. The cover is the first thing your body contacts and has a meaningful effect on how the surface feels temperature-wise. Natural fibre covers, cotton, wool, and bamboo blends, are more breathable than synthetic covers. Some covers are treated with phase-change material that genuinely feels cool to the touch, though that effect is most noticeable in the first hour of sleep. All Dozy mattresses use OEKO-TEX certified fabric covers. Adding a quality mattress protector made from natural fibres is also worth considering for hot sleepers, as cheap synthetic protectors can add an insulating layer that works against an otherwise breathable mattress.