Slumber Cloud Cooling Mattress Pad Review

slumber cloud nacreous mattress padThe Slumber Cloud nacreous mattress pad promises to help you keep 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, you’d expect it to be pretty good.

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 a good test this summer. I also tried out a set of their pillow covers to see if they’d stop me constantly turning my pillow over in the night to find a cool spot.

With the coupon code GOODNIGHT you can get a 10% discount at

Who is it for?

Anyone who feels that they overheat in bed can benefit from the mattress pad, for example:

  • If you tend to sleep hot.
  • If you suffer from hot flashes or night sweats.
  • If your mattress or mattress topper are made from materials that store heat more, such as memory foam. You can use this pad on top of it to mitigate the effect.
  • If you and your partner have different temperature needs.

Construction and materials

my slumber cloud nacreous mattress pad in the carry case

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 much less than that, and I found the elastic was tight enough to keep it tightly in place on my bed.

photo of the slumber cloud cooling mattress pad on my bed

Here is the mattress pad fitted onto my bed. The deep skirting with the tight elastic keep it tightly in place.

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 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

photo of my set of slumber cloud nacreous pillow coversI also decided to get a pillow cover set, which I liked a lot. They contain the same Outlast material and are the most effective cooling pillow covers I’ve seen. 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.



  • It does help keep your body cooler in bed.
  • It keeps working throughout the night.
  • There’s no smell out of the packaging.
  • It doesn’t rustle or make any noise when you move.
  • The elastic skirting fits all mattresses up to 20 inches deep. The elastic is tight enough to hold the pad in place well.
  • You can use it on top of a mattress or mattress topper.
  • It can help reduce the heat of materials like memory foam.
  • It’s hypoallergenic and machine washable (in cold water).
  • 30-day money back satisfaction guarantee, 90-day manufacturer’s guarantee.


  • It costs more than a standard mattress pad.
  • It doesn’t add much padding. If you’re looking for a topper to add more softness or firmness, the 1 inch of fill won’t make much of a difference.
  • It’s not a miracle cure if your bedroom is very hot. It will help, but won’t completely cool you if the ambient temperature is too high.


On the whole, I liked the Slumber Cloud nacreous 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 30-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.

Where to buy

You can use the coupon code GOODNIGHT to get 10% off at the official website of

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