Most people who sleep hot already know they sleep hot. You don't need a website to tell you that. What you probably don't know is why your mattress makes it worse, and which type of cooling mattress actually fixes the problem rather than just claiming to on the label.
We've spent years reviewing mattresses from every major UK brand and cooling is one of the things we specifically test. Some of what we've found goes against the usual advice.
Why Some Mattresses Make You Hot
Memory foam is the main offender. The cell structure is dense and closed, which means heat goes in but doesn't come back out. I've slept on full-foam models where you can feel the warmth building around your lower back within the first hour - it's not subtle. And it gets worse the heavier you are, because a heavier sleeper sinks further into foam that's essentially a heat sponge. Lighter sleepers sometimes get away with it because they sit closer to the surface where there's still some air moving.
Your mattress isn't the only thing making you hot though. Your duvet is probably doing as much damage. A thick tog rating in summer, a plastic-backed protector underneath, polyester sheets on top - any one of those can cancel out whatever cooling tech the mattress has. Worth thinking about before you blame the mattress entirely.
What Works and What's Just Marketing
Pocket springs. If you take one thing from this guide, make it this. A proper pocket spring core underneath the comfort layers creates air channels that let heat escape downward and out through the sides of the mattress. It's the single most effective cooling feature in any mattress and it's not even close. Every hybrid we've tested sleeps cooler than every all-foam model at the same price.
Latex is the other material that gets overlooked, and unfairly so. You'll see some sites lump it in with memory foam as a heat trap - that's wrong. Natural latex has an open cell structure, so air actually passes through it. It doesn't go soft when it heats up either, which means you don't get that stuck-in-treacle feeling that comes with warm memory foam. We've reviewed Dunlopillo's latex range extensively and the temperature difference compared to foam is hard to miss.
Gel gets a lot of marketing money thrown at it. Here's the honest version: it helps a bit when you first lie down because the gel absorbs some initial heat. Give it a while though and it reaches the same temperature as you. At that point it's just foam with beads in it. Better than plain memory foam, sure. Nothing like the cooling you get from springs or latex though.
Graphite is different and worth paying attention to. It conducts heat away from your body rather than soaking it up like a sponge. Origin uses it across their hybrid range and - to be fair to them - it does what the spec sheet says it does. Kaymed's AirLayer system takes another approach to the same problem. Both work properly, which matters because a lot of cooling claims in this industry don't hold up past the first fortnight.
Natural fillings are a different conversation. Wool and cotton don't actually lower the temperature of the mattress. What they do is handle the moisture. They absorb sweat and let it evaporate instead of leaving it pooling against your skin. For a lot of hot sleepers - and I'd count myself in that group - that dry feeling matters almost as much as the temperature itself.
Cover materials help at the surface. Bamboo, TENCEL, that sort of thing - they feel cooler against bare skin than polyester. They're a useful addition when the construction underneath is already doing its job, but they won't compensate for a heat-trapping foam core on their own.
Which Mattress Type to Buy
If you sleep hot, buy a hybrid with pocket springs underneath. That's the recommendation for the vast majority of people who ask us.
The springs handle the airflow. The comfort layer on top handles pressure relief. You get both without the deep sink that traps heat in an all-foam build. Most of the brands we recommend for hot sleepers fall into this category.
If you want to go the natural route, latex over pocket springs is hard to beat. Dunlopillo does this best in the UK. More expensive than foam hybrids, mind you, and heavier to rotate. But the cooling performance is a clear step up.
On a tighter budget, gel hybrids through Bensons (iGel) or Dreams (Therapur) give you cooling tech with the bonus of a showroom where you can actually lie on the thing before spending money. That counts for more than most people realise.
What I'd avoid: any thick all-foam memory foam mattress. Emma Original, Nectar Memory, Casper - the foam-only versions from all of these sleep warmer than their hybrid equivalents. If you want one of those brands, go hybrid. The pocket spring base makes a real difference.
Brands We'd Pick for Hot Sleepers
- Simba Hybrid Pro - probably our most recommended cooling mattress overall. The Aerocoil springs create proper airflow and the Simbatex foam is more breathable than standard memory foam. 200 night trial gives you long enough to test through a warm spell.
- Origin Hybrid Pro - the Ultra-Cooling Graphite layer is the standout here. It pulls heat away actively rather than absorbing it. Over 5,700 pocket springs underneath. Slightly less well known than Simba but the cooling spec is stronger on paper. 200 night trial, 15 year warranty.
- iGel through Bensons - gel over pocket springs, tryable in any Bensons store. We've tracked this range for years and the cooling holds up long term, which isn't something every gel mattress manages.
- Therapur through Dreams - ActiGel technology, pocket spring base. Same showroom advantage as iGel but through Dreams instead. If you've got a Bensons and a Dreams near you, try both.
- Coolflex Hybrid Ice - the value pick. Through MattressNextDay. Cooling performance punches above the price.
- Hypnia - bamboo cover, pocket springs, latex layer. European-made. Less marketing budget than the big names, stronger spec for the money. 200 night trial, 15 year warranty.
Fix the Rest of Your Bed Too
Getting the mattress right is the first step. Everything else on the bed is step two, and honestly it's where a lot of hot sleepers trip up.
Your duvet is almost certainly too thick for summer. Drop to 4.5 tog or less from May onwards. Wool-filled duvets breathe better than synthetic at any tog - and if you're using the same 13.5 tog year round, which a surprising number of people do, that alone might be why you're waking up damp.
Protectors with plastic backing will undo everything the mattress is trying to do. Swap for a breathable membrane version. The price difference between a plastic-backed protector and a breathable one is modest but the effect on temperature is significant.
The NHS says about 18 degrees for sleep. Most bedrooms run warmer. Open a window, adjust the heating timer, use a fan. All straightforward changes that make a real difference.
Cotton or bamboo sheets breathe well and polyester traps heat, so the switch is worth making if you haven't already.
How We Test for This
We don't just read the spec sheet and repeat the marketing. When a mattress comes through our rotation we look at the spring type, foam density, whether the cells are open or closed, what the cover is made of. A mattress with "cooling" on the label that's actually a thin gel layer on dense memory foam isn't a cooling mattress. It's a warm mattress with better branding.
