Why does memory foam get hot?

This is one of the most frequently asked questions. Memory foam works by reacting to heat which allows the materials open cell structure to change and flex to the warm shape placed upon it. Like any foam, it will retain heat.  For some people, this is not a problem they barely notice, but for other ‘hot sleepers’ they have complained that it becomes too hot. It really is a personal preference but by its very nature memory Foam is heat-retentive.

Thermometer john ryan

Due to Memory Foam reacting and softening to heat it can, therefore, feel softer in the summer warmer months and firmer in the winter. This depends on the temperature of the room. Some people love the heat retention and comment how it keeps them nice and warm. Others dislike the heat and prefer a cooler material such as a Hybrid Foam mattress or Latex. All foams will, however, be warmer and more retentive than a Pocket Sprung Natural Mattress, again it is personal preference.

The new Hybrid range of mattresses uses more innovative types of foams that have heat dispersing properties. These Hybrid foams evenly distribute the heat through the material providing a cooler sleeping experience for the person, such as Coolblue or don’t rely on heat at all to provide their softness and comfort, Laygel is a perfect example of this. Latex is naturally breathable allowing air to circulate preventing the mattress from retaining too much heat.

There are also aeration layers, such as castellated foams, that are put into mattresses which have benefits and drawback as well. Due to the fact that castellations can change the feel and firmness of the foams we don’t currently use or manufacture with these methods. We believe with the newer Hybrid Foams and Latex this is unnecessary.


Our advice if you’re concerned is to either try out a memory foam mattress from a friend or in a hotel first to establish just how warm you will get. Another idea is to change the tog of your duvet, kind of bed sheets you have or room temperature. Failing that if the temperature is the main concern we would advise either a Hybrid Foam, Latex or Traditional Pocket Sprung mattress.The preference is really down to you, If you took two people on the same winters day and gave them an identical jacket, one may feel smothered in it whilst the other loves the snug feeling so it really is very subjective.



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  • Mike Ryder says:


    I recently purchased two very expensive ottoman tempur beds from dreams. At first they were fantastic, but after a year of use my wife and I are noticing that we are waking up incredibly hot in the night. I am now worried that my ‘investment’ is no wasted. What do you advise we do to reduce the heat? is there a better bed out there that we can use on the base to try and minimise the loss if we need to change our tempur mattress for a cooler mattress?

    Hi Mike, Unfortunately all memory foams retain heat. Although Tempur use their own patented pressure relieving foam the result is often the same around heat retention. You may also find that your Tempur mattress is harder in the winter or when the room is colder, which also is linked to the requirement of the these foams to warm up before they mould to you. Unfortunately apart from changing the tog of your duvet there is no easy way to remove the heat from such foams, even using different bedding such as Coolmax bedding will only go so far.

    The alternative is to replace the mattress with one that has a lower Visco elastic threshold, ie doesn’t rely on heat as much or at all to mould. Hybrid and Latex foams are ideal for this. Hybrid foams are an innovative improvement on memory foam, reducing the heat and also being more responsive. They still will get warm to some degree, which some people love. Latex is the least heat retentive of the foams and is a premium foam. If heat is a real concern the only way to reduce it even further is to go for a traditional pocket sprung bed, such as our John Ryan By Design range, but a lot of people choose foam for the pressure reliving qualities which foams are excellent at. Please have a look at our hybrid and latex beds for more detail. I hope that helps. Lee

  • Tammy says:

    Me and my husband bought a memory foam mattress and after a slightly toasty winter are now really concenwd about the heat come summer. We find ourselves waking up sweating and clammy. What advice would you give us Lee? Tammy
    Hi Tammy, unfortunately in your case one of the features of memory foam is that it retains heat. This means once you’re in bed it will reserve your body heat to help it mould. Some people who get cold in bed love this others hate it as they over heat. The only way to avoid this is to use a natural material like we use in our traditional John Ryan by design artisan range. Latex is cooler than memory foam but if you’re struggling with heat it will still be warmer than a traditional bed because it’s a denser material.

    my advice would be to add a natural topper like a down or wool topper to try and limit the heat of the bed. You could add a latex topper but if you’re really warm this would only reduce the heat build up slightly. As I always say you an only tweak a bed with a topper and not ‘make a bad bed good’ I’m afraid!


  • Rob says:

    Hi Lee

    Thank you for getting back to me so quickly and the very helpful advice. As it sounds like the topper is not the ideal solution would you be able to recommend a few full mattresses? I currently a kingsize slatted bed and would like to stick with the latex / form option I think. Both myself and my partner weigh about the same around the 12 stone mark.

    Thanks in advance.

    Hi Rob,Given that you’re finding the tempur mattress warm I’d recommend looking at Latex as its a natural product that is breathable and less heat retentive. It will still be warmer than say a traditional wool filled pocket sprung mattress but less heat retentive than tempur or memory foam.

    I’d recommend either the fusion 1 or fusion 3 which are medium density solid core latex mattresses. They are fully turnable, unlike memory / tempur mattresses and comes with removable matching turnable toppers giving you four sides to your mattress. I would ask that if you haven’t tried latex that you maybe goto furniture village or somewhere that stocks latex mattresses. This is just to confirm that the sensation of latex, which is much more responsive than memory or tempur foam is to your liking.

    With a slatted base Rob we always recommend they are boarded over for latex and foam to stop settlement and dips where the foam conforms to the gaps, there is a link here to our guidance page.

    We provide comparators to the fusion range which are on the shop pages, where you can see whats close to our range in retailers. I would stress that our Latex range is higher than the majority of retailers latex as ours is natural and not fully synthetic. If you need any more help Rob I’m happy to discuss this over the phone with you as I know the world of mattresses can become very confusing! Lee

  • Di says:


    I would appreciate your help.

    I suffer from dermatitis/eczema and night heat problems and I have been advised to change to a latex mattress.
    I have a few questions:
    Would the solution be the Fusion 5 100% Natural Latex Core medium?
    I am used to a firm pocket sprung mattress. How does the medium latex compare to a firm pocket sprung?
    Is it feasible/possible to have a firm latex?
    I would need to purchase a topper and am interested in the LayGel. What is the difference in comfort and support between the 5 cms and 7.5?
    I will replace my current double base to a king size. Can this Fusion 5 mattress be used on a slatted base bed or does it require a divan base?
    I have viewed your video and read your web pages. Can I double check that this is the best mattress to go for with the least chance of any long term smell?
    And finally can I also ask if I place an order, once I have your reply, then the delivery would be in 4 weeks time.

    Hi Di, Can I ask who advised a latex mattress given night heating problems? The reason I ask is that whilst latex is breathable and the least heat retentive of mattress foams, its not as cool as say a traditional natural filling mattress. If you have concerns about over heating I wouldn’t recommend jumping from a pocket sprung mattress to a solid core latex mattress.

    In terms of a comparison; pocket sprung traditional mattresses have a completely different sensation to solid core natural latex. The latex has a progressive sink and comfort feel which is hard to articulate, its much more pressure reliving than say a pocket sprung mattress but then has the draw back that you can’t for example have a dual tension latex mattress or edge support. I would advise you try some latex mattresses to compare to your current mattress.

    It is feasible to have a firm latex such as 80kg Latex. I would need to know your bodyweight to give an idea of the tension that would suit you.

    I would ask you to look at the Fusion 3 solid core latex mattress, which has matching latex topper, rather than match a laygel topper with a latex mattress. The laygel topper is soft so it would give an even softer feel to the latex top layers. The deeper 7.5cm laygel topper would provide a deeper sink than the 5cm topper.

    I wouldn’t recommend putting a foam or latex mattress on a slatted base, we have some guidance here if you do have one. We always advise they are boarded over for this type of bed.

    There will be some off gassing with all mattresses including latex, the duration of this is subject to ventilation and the individuals sensitivity to new smells. I couldn’t give any guarantee that this would be more or less than another material because again its very subjective Di!

    I’ve probably raised more questions than you were expecting Di but want to make sure you have checked and tested all the variables before buying a new mattress. – Lee

  • Julia says:

    Hi You have been recommended from a friend who has recently had a mattress from yourself.
    We are looking for a new mattress and currently have a memory foam mattress. We prefer this to a traditional mattress but find it really hot. Can you make any recommendations for a cooler type of mattress whilst not returning to a traditional sprung mattress? Many Thanks

    Hi Julia, Thanks for getting in touch, I’m glad that a previous customer has recommended us.

    We have a full range of hybrid foam mattresses which are less heat retentive than say memory foam, as in they don’t require or retain as much heat to work. Have a look at the Hybrid 4 or 5 for a alternative to memory foam to get you started. We also have a solid core latex range which is cooler still but has a slightly different sensation to memory foam, probably feeling more supportive but still with that progressive sink feeling.

    If you can let me know your preferred tension, body weight and height I can advise further. If you want to give us a call I’d be happy to assist you. 0161 437 4419. Lee

  • Lisa says:

    I have gone memory foam mattress because it was making
    Me have hot sweats worse which am prone to.
    Iv recently bought pocket sprung mattress which am finding
    Is to firm . Can you please recommend a topper please .
    Thank you
    Hi Lisa,

    Thanks for getting in touch. Some people find memory foam and all foams much warmer than say a traditional pocket sprung mattress.

    We do have a range of natural latex toppers which would soften the top layer that said they would still be warmer than say a goose down or natural fibre topper and this is something to bear in mind.

    Our latex toppers are found here. Lee

  • TJ says:

    Hi , Just found your site, My wife and I are heavy weights me 95Kg wife is 60kg.

    We at the moment have two mattress,s on top of each other as we like a softish feel.
    On a slatted bed , recently slept on a Nid ‘ Or (memory foam?) mattress in paris and had the best nights sleep in a long time.
    Concerned because we are both ‘hot’ sleepers on memory foam !

    Would your Fusion 1 suit us do you think ?

    Hi TJ, For your weight if you like a softest feel the fusion 1 would be ideal. It will have a medium support for your partner but the fact that it has a removable turnable topper it will give a softer top feel as well for her. Latex is cooler than memory foam but not as cool as natural fibres such as wool. Heat is quite subjective but if you found a memory foam mattress in paris ok then latex will be cooler than this. The fusion zero would be quite firm for your wife and a medium for you. It doesn’t have as much sink as the fusion solid core range. Hope that helps – Lee

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