Cooling mattress: which one generates the least heat and how to choose
In short
A cool mattress is one that lets heat and moisture escape your body: a ventilated pocket-sprung core, layers that don't close in on you, and breathable fabric. Those that tend to run hottest are usually made of dense, untreated memory foam. At Morfeo, the coolest is the VisCool, with a PCM thermoregulating fabric that absorbs excess heat and releases it; next is the Altus, with natural linen, followed by the Nature.
By the Morfeo team · made in Yecla (Murcia) · updated October 11, 2026
In this guide
- Why a mattress runs hot
- Which mattress runs hottest?
- Which materials are coolest
- What is a thermoregulating mattress
- The coolness ranking of Morfeo mattresses
- Which cool mattress to choose
- Protector, pillowcase and sheets: what makes the biggest difference
- Tips for sleeping cool in summer
- Trial, warranty and delivery
- Frequently asked questions
Why does a mattress run hot?
While you sleep, your body releases heat and moisture. If the mattress and what you put on top don't let them escape, they build up between your skin and the bed, and you wake up uncovered, turning the pillow to find the cool side. Five things have an impact:
- The material of the top layers. This is what touches your body. Very dense, closed-cell foam retains heat; an open structure lets it pass through.
- How much you sink in. The more the mattress envelops you, the more surface area of your body is in contact and the less air circulates around you.
- The core. A pocket-sprung core has open space between the springs for air to move through. A block of foam does not.
- The cover and protector. A good mattress with a plastic-backed protector becomes hot. The fabric you touch matters as much as what's inside.
- The base. A mattress resting on a closed surface does not ventilate from below. Bases and storage beds with a breathable top or perforated board allow moisture to escape.
Which mattress runs hottest?
Generally, untreated dense memory foam mattresses with foam cores. Classic memory foam softens with your body temperature and moulds to you: it's very comfortable, but it envelops you and leaves little room for air. If the entire core is also foam, heat has nowhere to go.
That doesn't mean memory foam should be ruled out. Open-cell or thermally treated memory foam placed on a spring core behaves very differently. In fact, the coolest mattress in our range, the VisCool, uses memory foam: what changes is how it's made and what accompanies it.
The practical conclusion: don't choose based on the name of the material, but on the complete construction. Core, layers, fabric and what you put on top.
Which materials are coolest?
| Material or component | How it behaves with heat | What to look for |
|---|---|---|
| Pocket springs (core) | Allow air to circulate between the springs | That the core is made of springs and not a block of foam |
| Classic memory foam | Envelops you and tends to build up heat | Whether it's open-cell, whether it has a thermal treatment and how thick it is |
| Open-cell or treated memory foam | Retains considerably less heat than classic memory foam | That the product sheet explains the treatment, not just that it says "cool" |
| Latex | Elastic, you sink in less; breathes better than classic memory foam | Whether it's perforated and whether it's on springs |
| PCM (phase change) fabric | Absorbs excess heat and releases it when your temperature drops | That it's in the layer that touches your body |
| Linen and natural fibers in the fabric | Absorb moisture and breathe | That they are not covered by a plastic-backed protector |
If you're torn between latex and memory foam for other reasons, you can find the full comparison in the guide to natural latex mattresses and the one for memory foam or springs.
What is a thermoregulating mattress?
It's a mattress that not only lets air pass through (passive coolness), but also manages heat actively. The most common form is a fabric or a layer with phase change material, PCM: microcapsules that absorb heat when your body warms up and release it when it cools down. The result is a more stable surface during the night.
Two warnings to avoid being misled:
- "Breathable" is said by almost any product sheet. Look for an explanation of how: what core, what layers, what fabric.
- No mattress can compensate for a very hot and unventilated room. It helps a lot, but the bedroom also counts (we'll see that further down).
The coolness ranking of Morfeo mattresses
We'll tell you clearly, from coolest to least:
VisCool
PCM fabric on the top, which absorbs heat when your body generates too much and releases it when your temperature drops. Below, open-cell VisCool foam with cooling balm and a pocket-sprung core. Firmness rating: firm, 26 cm, and removable cover.
Altus
Natural coolness, without artificial technologies: linen outer fabric, which absorbs moisture and regulates temperature, over more than 2000 pocket springs. Medium-firmness and 28 cm.
Nature
Natural latex and organic cotton topper over pocket springs. The most welcoming of the range (medium firmness) and third in coolness, behind the previous two.
All models designed for heat are in the collection of cool mattresses for summer.
Which cool mattress to choose?
| If… | We recommend | Why |
|---|---|---|
| You wake up sweating even though you've tried other mattresses | VisCool | It's the only one in the range with active thermoregulation (PCM), in addition to ventilation |
| You want to sleep cool with natural materials | Altus | Natural linen that breathes; one firmness level less firm than the VisCool |
| You're a couple and one person gets hotter than the other | VisCool or Altus | Pocket springs: if the hotter person turns over looking for the cool side, the other barely notices |
| You weigh more than 95 kg | Morfeo XL | All Morfeo mattresses are guaranteed up to 95 kg per person; the XL is designed for over 100 kg |
| It's for a child or teenager | Juvenil Lite | 4 cm perforated memory foam layer that allows air to circulate and a washable cover |
If firmness also concerns you besides heat, cross-reference this guide with the one for firm or soft mattress. And if you sleep together, with the one for the best mattress for couples.
Protector, pillowcase and sheets: what makes the biggest difference
Changing what you put on the mattress is the cheapest way to sleep cooler, and the first thing we recommend trying if your mattress is still in good condition.
PCM thermoregulating technology in a fitted sheet format: protects the mattress from moisture and stains and gives a cool sensation. Machine washable at 30 °C maximum.
- Avoid plastic-backed protectors. If your mattress is cool but the protector doesn't breathe, you lose a good part of the advantage. If you're not looking for a cooling effect but do want breathability, the Tencel protector is waterproof and breathable.
- The pillow also runs hot. The FreshCool pillowcase has phase change microcapsules and is compatible with all Morfeo pillows.
- Percale cotton sheets. Percale is a lightweight and breathable fabric. Our EcoPercal sheet set is made of certified organic percale cotton.
- A base that ventilates. Look for a breathable top or perforated board, like in the Kos base (breathable 3D top) or the Samos base (multi-perforated board), so that the mattress breathes from below. You have them all in upholstered bases.
More protectors in the collection of protectors. Remember: textiles are delivered in 3-4 days and can be returned within 14 days if they haven't been used; the 100-night trial is only for mattresses.
Tips for sleeping cool in summer
The mattress is one part of the problem. These habits help, whatever mattress you have:
- Close blinds and curtains during the day so the sun doesn't heat the room, and ventilate at the end of the afternoon or early morning, when it's cooler outside. If you can, open two facing windows to create a draft.
- Use the fan to your advantage. Pointed to move the air in the room, not directly at your face all night.
- Remove layers from the bed. In summer, the duvet is unnecessary: a light top sheet or nothing.
- Lightweight sleepwear, made of cotton or linen, that absorbs sweat.
- A warm shower before going to bed helps you get into bed without the accumulated heat of the day.
- Eat light and drink water during the day, without drinking it all before bed.
- Manage humidity. In coastal areas, the stuffiness is as bad as the temperature: ventilate well and use textiles that absorb moisture.
If you sweat a lot at night even though the room is cool, or it happens all year round, consult your doctor: there may be causes that have nothing to do with the mattress.
Test it in the middle of summer
Trial, warranty and delivery of the mattress
- 100-night trial. No minimum number of nights: if you're still hot, return it and we'll pick it up for free.
- 10-year warranty. Covers manufacturing defects.
- Delivery in 3-7 business days on the mainland.
- Free shipping on the mainland.
The 100-night trial and the 10-year warranty are for mattresses; they do not cover protectors, pillowcases or sheets. We manufacture to order in Yecla (Murcia).
Frequently asked questions
Which mattress runs hottest?
Generally, untreated dense memory foam mattresses with foam cores: they envelop you and leave little room for air. Open-cell or treated memory foam, on pocket springs, behaves very differently. More than the material, the complete construction matters: core, layers, fabric and protector.
Which mattress is the coolest?
The one that combines a ventilated core, such as pocket springs, with layers that don't close in on the body and a fabric that breathes or thermoregulates. In the Morfeo range, the coolest is the VisCool, with thermoregulating PCM fabric; next is the Altus, with natural linen, and then the Nature.
Which is better for heat, latex or memory foam?
Latex breathes better than classic memory foam and you sink in less. But an open-cell memory foam with thermoregulating fabric, on pocket springs, can be cooler than a latex mattress. That's why at Morfeo the VisCool, which uses memory foam, is cooler than the Nature, which uses latex.
What is a thermoregulating mattress?
A mattress that, in addition to ventilating, manages heat actively. The usual form is a fabric with phase change material (PCM), which absorbs heat when the body warms up and releases it when it cools down. At Morfeo, the VisCool Mattress has it.
How can I make my mattress run less hot without changing it?
Change what you put on top: a breathable or thermoregulating protector instead of a plastic-backed one, percale cotton sheets and a cool pillowcase. Also check that the base lets the mattress ventilate from below and ventilate the room during the cooler hours.
Does a mattress protector help prevent overheating?
Yes, if it's breathable. A plastic-backed protector makes any mattress hot. Morfeo's FreshCool protector has thermoregulating PCM technology and the Tencel one is waterproof and breathable. Both are washed at 30 °C maximum.
Which cool mattress do I choose if I weigh more than 95 kg?
All Morfeo mattresses, including VisCool, Altus and Nature, are guaranteed up to 95 kg per person. If you weigh more, the Morfeo XL Mattress is for you, designed for people over 100 kg, and you can complete it with a FreshCool protector.
If you get hot at night, start with the VisCool
It's Morfeo's coolest mattress: active thermoregulation, pocket springs and firm firmness. You have 100 nights to test it in the middle of summer.
