Slumber Cloud Cooling Mattress Pad Review

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Slumber Cloud Performance Mattress Pad-min

In the photo above, I have the Slumber Cloud core mattress pad set up in my new bedroom, with the comforter on top ready to be used too in the hot New York summer.


The Slumber Cloud mattress pad is an effective cooling mattress pad that can help you sleep more comfortably. Whether you’re a hot sleeper, suffer from night sweats or hot flashes, or just live in a region with very hot summers, it will help dissipate the heat your body creates in bed.


  • Helps keep your body cooler throughout the night.
  • Made from high-quality materials, with a robust design.
  • The elastic skirting fits all mattresses up to 20 inches deep.
  • Fits on top of a mattress or mattress topper.
  • Hypoallergenic and machine washable (in cold water).
  • 60 day returns policy, with shipping paid for by them, even if washed. 180 day warranty.


  • It doesn’t add much additional padding.
  • It won’t change the temperature of your bedroom, but does dissipate heat from underneath you.

Full review

The Slumber Cloud core mattress pad promises to help keep you cool in bed by dispersing your body heat from underneath you.

It uses fabrics containing Outlast Technology, which is a cooling method originally developed for NASA. So with a claim to fame like that, I was expecting great things.

I tend to quickly overheat in bed, and my experience is that bed cooling isn’t so easy to achieve – especially in a hot bedroom with no air conditioning in the summer.

I’ve used several cooling mattress pads and bed fans in recent years, and I’ve come to a simple conclusion: there’s no perfect solution to bed cooling, but your choice of bedding can definitely make a difference.

So I decided to give the Slumber Cloud nacreous mattress pad and pillow covers a good test this summer.

Construction and materials

Note that on the packaging in the photo below, it’s called the Nacreous Mattress Pad. Since I bought mine, they changed the name to ‘Core Mattress Pad’. The materials and functionality remain the same though.

slumbercloud mattress pad in the original bag

Out of the packaging, it’s immediately obvious that the mattress pad is well made. It has a soft feel to the touch, but also looks like it will last the test of time.

The outer cover is a quality 300 thread count, made from 40% Outlast viscose and 60% cotton.

The inner lining consists of 100% polyester fiberfill and the Outlast material. That adds some fill to the pad – probably about an inch of loft in total.

I liked that it has a very deep stretchy skirting, with a strong elastic band to keep it in place. The skirting will fit a mattress up to 20 inches deep. My mattress is less than that, and I found the elastic was tight enough to keep it tightly in place on my bed.

Below: The Slumber Cloud mattress pad set up on our bed. It comes with a wide skirting so you can attach it to a thick mattress.

the slumber cloud mattress pad set up on my bed

How does the cooling work?

The way the Slumber Cloud pad actually keeps you cool can be a little confusing. The simple answer is that it’s all about some little beads called ‘thermocules’ which are in the Outlast material.

As your skin temperature increases, those thermocules absorb your excess heat and store it away from you. And if your body temperature drops enough in the night, they return some of the warmth to keep you comfortable.

To find out more about how this works, I got in touch with Slumber Cloud. Here’s what they told me:

Thermocules™ is the trademarked name for the housing of the technology. These are essentially microscopic beads comprised of a “shell” that will change states (from a solid to more of a gel) when the temperature changes.

As your skin temperature increases, the technology will absorb that excess heat to reduce overheating. The technology will then store the excess heat away from your body until your skin temperature begins to drop. When this occurs, the stored heat is released back to you to keep you at the perfect temperature.

More about Outlast technology

To understand better how it works, I decided to see what the makers of the Outlast technology part have to say about the way the thermocules work.

They explain that the technology was originally developed for NASA, and add the following:

Outlast® technology, originally developed for NASA, utilizes phase change materials (PCM) that absorb, store and release heat for optimal thermal comfort. Outlast® technology is comparable to ice in a drink; as it changes from solid to liquid, it absorbs heat and cools the drink, keeping that drink at the desired temperature for longer.

So there you have it: you are the drink that slowly gets too warm, and the mattress pad is the ice cube that helps keep you cool. And the best bit is that it’s an everlasting ice cube that returns when you cool down or move to a different part of the pad!

My experience using the mattress pad

The Slumber Cloud pad arrived nicely packaged in a plastic carry case, which is good for future transportation.

The pad looks smart, which I liked, with enough box panels to prevent the inner lining from bunching. It was very easy to fit, with the skirting and elastic band holding it strongly in place on my bed. I put a cotton sheet over the top too, wanting to see if it works through a sheet (it did).

That first night, I definitely noticed that it felt a little cooler to lie on than just the mattress. It also added a thin layer of plush padding, which felt comfortable under my body without altering the firmness much.

I woke a couple of times in the night as usual and noticed that I didn’t feel too hot, which was great. But it wasn’t a particularly hot night, so a bigger test would come later.

Over the next couple of weeks, there were a few sweltering summer nights, so the pad got a thorough testing.

What I found was that it stopped me from feeling uncomfortable where my body was in contact with the bed. I don’t think it cooled my entire body as such, and I still felt a bit warm on some of the hottest nights.

But it was great not to wake up feeling like there was sweat between me and the bed! And that cooler period at the start of the night made it easier for me to tolerate the heat and fall asleep easier.

It also made a pleasant change not to be constantly moving around in the hunt for a cooler spot. So all in all, I was happy with the difference it made.

The pillow covers

slumber cloud pillow covers

I also decided to get a pillow cover set to see if they would add some extra cooling effect.

They contain the same Outlast material, and I found them very comfortable to use in hot weather. So much so that when on holiday recently, I packed one in my suitcase!

I like that they are very well constructed, just like the mattress pad. Being hypoallergenic and having a solid zip, they are perfect for my dust mite allergy.

They feel lovely and soft, with a 350 thread count outer cover. And the Outlast fabric on both sides of the pillow cover helps keep your head a little cooler in the night.

I really noticed the difference with the pillow covers, as that extra cooling seemed to go a long way in helping me feel comfortable.

Cleaning and maintenance

Considering all the mention of ‘technology’, the Slumber Cloud pad is actually very easy to clean. You can wash it in cold water, tumble dry on a low heat and then hang to dry.


On the whole, I liked the Slumber Cloud core mattress pad (and pillow covers) enough to decide to keep using them throughout the summer.

As I half expected, it didn’t keep me completely cool on the hottest of nights. But it definitely helped and made a significant difference on some nights.

I think it’s important to understand that if your bedroom is unbearably hot, no cooling mattress pad will change the fact that the air temperature is unpleasantly high.

What it can do is help you remain comfortable by absorbing some of the heat your own body is producing. And for me, this mattress pad did a better job of that than previous cooling pads I’ve tried.

Importantly, it was better than sleeping on a normal mattress or mattress topper. So I think with a no questions asked 60-day money back guarantee, it’s worth giving it a go if you’re suffering from overheating and feel that a change in your bedding would help.

Update: trying the Slumber Cloud comforter, mattress protector, and sheet set

four pieces of slumbercloud bedding in the original packaging

In the photo above, you can see the bedding I used. Since I got mine, they have simplified the product names. For example, the Cumulus Lightweight Comforter is now just called the Lightweight Comforter.

After a couple of years of using the mattress pad, I decided to try out some of the other bedding items they make: the dryline mattress protector; comforter and duvet cover; and sheets.

Dryline mattress protector

The mattress protector is also made with the Outlast technology – the norm with all of SlumberCloud’s products.

It’s 100% waterproof, so if you have a problem with sweats at night, it’s a good way to protect your mattress. I tested it with some water spillage, and it held up well.

It’s kind of hard to tell really, but I felt that the additional layer of the same cooling system perhaps also helped with the cooling under the mattress pad.

The comforter

The comforter in some ways turned out to be my favorite item – even more so than the mattress pad at times.

It feels beautifully soft and is incredibly lightweight. I found I could use it in warmer weather (though not the hottest) when there was no way I could use a normal comforter.

It’s always nice to have a layer on top of you, so the fact that this one lets you have that comforting layer a little longer into the warmer months of the year was something I appreciated.

The stratus cooling sheet

Combining premium cotton and that outlast part again, the sheets feel great. I don’t think they do much to actively cool you, but compared to many other sheets, they just feel so light and soft.

I was able to use a top sheet during a particularly sweltering steamy New York summer, which was a pleasant change from trying to sleep with no covers at all.

Which parts of the Slumber Cloud set are best?

This is a difficult question to answer. I think the most important item is the mattress pad, as that’s the one that will help reduce heat under your body. Following that, the pillowcases will also help dissipate heat under your head.

Then I’d probably go with either the comforter or a top sheet if you’d like to sleep with a lightweight cover over you.

Finally, if you want the whole system, the dryfit mattress protector is worth adding. Though in some circumstances, you might benefit from that before the comforter or sheet.


  1. Thanks Ethan for your review. I want to try this Slumber Cloud Cooling Mattress Pad before forking out the big bucks for the ChiliPad. I’ll let you if it will do the trick in addressing my sleeping hot tendencies.

    • Hi Aimee
      You’re welcome. I’d love to know what you think of it! Honestly, I think the ChiliPad is a more effective mattress pad for many reasons. But perhaps if you just need a little cooler surface to sleep on, the SlummberCloud will help and at a much lower cost.

  2. Dear Ethan,

    I loved your review, and as a result, I will be purchasing the pad and the sheets, when the pad is back in stock. I would really like to know how many inches thick the pad is, and can’t seem to find the answer, but figured you would know…

    Thanks so much,

    • Hi Debra
      I’m happy to hear the review was useful. It’s a pad, and not a topper, so much thinner than you’d get from a thick memory foam topper for example. So it’s actually no more than an inch thick. Not one to add a huge amount of softness then.

    • Hi
      No need as it’s a pillowcase itself, so I use just that. I guess you could if you wanted to, but it’s not necessary.

  3. I’m wondering how this might work in combination with the Chilipad. That is what I currently use and on some nights it is still just a little to warm for me. I don’t know if having the water-cooled pad between me and the Nacreous would render it ineffective or if it would still absorb the excess heat.

    • Hi Bret
      I would lean towards not combining them. I can’t imagine it helping, and actually more likely to reduce the effectiveness of the Chilipad. You could give it a go and send it back if it doesn’t work. But that’s kind of a hassle, especially if it’s not likely to help much. If you decide to, please do let me know how it worked out!

    • Hi Alyse
      It should do as far as I’m aware. You could always give them a call and check if it’s compatible with your particular mattress brand.

  4. Hi Ethan, thank you for your very thorough review. I’m thinking of buying the mattress pad as this seems to be the best option from the various products I’ve seen they make. I wanted to ask your opinion about combining the mattress protector and pad. Do you think that having an extra layer of the cooling tech would make any difference? Or can I just keep a normal protector, which would be less expensive, and rely on the topper alone to bring me enough cooling?

    • Hi Edwin
      I’m glad to hear the review was helpful. To be honest, I’m not entirely sure how much of a difference it would make. I haven’t seen any facts or theory about this. It would make sense that adding an extra cooling layer could help, but at the same time, I wouldn’t like to claim that it definitely makes such a huge difference that you’d be missing out in not betting both.
      I tried the pad on its own for a while and found it very helpful. I then at a later point got the entire set to see what the difference might be. It definitely felt like an improvement, especially the pillow cases and top sheet, both of which I really like. But did the addition of a protector under the original pad make a noticeable difference? It’s hard to say, so my feeling would be to start with the pad if you’re on a budget. Then you can try both at a later date if you feel it helped and want to go even further. But if you can stretch to it, I’d definitely try the pillow cases too as they feel great under your head in hot weather.

  5. Does it matter what type of sheets you use – cotton, microfiber, or Bamboo? Will the mattress protector still work?

    • Hi Joanie
      That’s a good question. I personally use the SlumberCloud sheet set on top of the mattress protector, so hadn’t thought much about how effective it would be with standard sheets. I imagine the best bet would be to use as cool and light material as possible, so a good quality cotton or bamboo probably. Then I see no reason why the mattress protector wouldn’t do its job still. I’d ask SlumberCLoud customer support before buying though, just to be on the safe side. They are good at responding to queries in my experience.

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