Simba TripleShield Tencel Cool Mattress Protector review: "comfortable, breathable and noticeably less clammy"

RRP at time of testing: from £59 | Check price at Simba or Amazon

My rating: 5 out of 5 stars

My verdict

If your child sleeps hot, a waterproof mattress protector can sometimes make matters worse. Plenty of cheaper options trap heat, rustle every time they move and leave the bed feeling a bit like it's wrapped in cling film.

Thankfully, that wasn't my experience with the Simba TripleShield Tencel Cool Mattress Protector.

Our youngest has the warmest room in the house - so it made sense that he sleep on this one

I tested it on my youngest son's bed over 30 nights. His bedroom is consistently the warmest room in our house, regardless of the season, so he was the obvious choice for testing Simba's cooling claims. He slept on it every night, usually from around 8pm until 7am, giving us roughly 330 hours of real-world use.

The biggest surprise was how unremarkable it felt - in the best possible way. Once fitted beneath the sheet, it simply disappeared. There was no obvious rustling when my son moved around, no clammy feeling against the mattress and none of the plasticky sensation I've experienced with cheaper waterproof protectors over the years.

The cooling effect is subtle rather than revolutionary. It doesn't transform a warm bedroom into an air-conditioned hotel suite, but it also doesn't add to the problem. During some warmer nights it just stayed comfortable, never creating that sweaty, sealed-in feeling that waterproof bedding can sometimes cause.

The protector comes neatly packaged and Simba's branding is distinct

At £59 for a single, it certainly isn't cheap. I wouldn't rush to buy one for a spare bedroom that's only used a handful of times each year. But if you've invested in a decent mattress - or you've got a naturally warm sleeper whose bedroom always seems a few degrees hotter than everywhere else - I think it's a worthwhile upgrade over a budget waterproof protector.

How we’ve tested the Simba TripleShield Tencel Cool Mattress Protector

We tested the Simba TripleShield Tencel Cool Mattress Protector on my youngest son's bed over a 30-day period.

His bedroom is the warmest in our house, making him an ideal real-world tester for Simba's cooling claims. He slept with the protector on his Simba mattress every night throughout testing. 

He’s also the child in our family that sleeps the longest - usually between 7pm and 7am, which is slightly longer than his older brother. 

Simba TripleShield Tencel Cool Mattress Protector: what’s in the box?

There's very little to say here. Inside the box you'll find the mattress protector itself, folded and ready to fit straight onto your mattress. There are no extra layers to assemble or confusing instructions to decipher.

Like a fitted sheet, it slips over the mattress using an elasticated skirt.

Simba says it's designed for mattresses up to 40cm deep and it's available in Single, Small Double, Double, King, Super King, EU Single, EU Double and EU Queen sizes.

First impressions of the Simba cooling mattress protector

Straight out of the packaging, this immediately felt more premium than many waterproof protectors I've used previously. Instead of the stiff, shiny finish that often makes waterproof bedding feel like emergency camping equipment, the Tencel surface is soft and smooth to the touch.

It's also surprisingly thin. That's worth mentioning because some people assume "premium" means thick or padded. It isn't. This isn't trying to replace a mattress topper or make your mattress feel softer. Its job is simply to protect your mattress without making the bed less comfortable. Judging purely by first impressions, it looked promising.

Inside you'll find just the protector - no extra packaging or unnecessary materials

Simba TripleShield Tencel Cool Mattress Protector: what’s it like to sleep on?

My youngest slept on the protector every night throughout the month without mentioning it once. Normally, that would sound like a strange compliment. In mattress protector terms, it's exactly what you want.

Underneath a fitted sheet it became virtually invisible. The protector didn't alter the feel of the mattress, didn't bunch up underneath him overnight and stayed securely fitted throughout testing.

Given that his bedroom is the warmest in our house, I paid particular attention to whether the waterproof layer would make him feel hotter overnight. Fortunately, it didn't.

I wouldn't describe the experience as actively cooling in the way a fan or cooling mattress topper might feel. Instead, the Tencel surface simply avoids the heat-trapping, clammy sensation that some waterproof protectors create.

My youngest isn't quite as theatrical a sleeper as his older brother, but he still changes position plenty throughout the night. At no point did I notice the familiar crinkling soundtrack that often accompanies cheaper waterproof protectors.

What’s Simba’s cooling mattress protector like to clean?

Over the 30-day testing period, the protector only needed routine washing rather than emergency laundering after accidents.

Simba recommends washing the protector separately on a gentle cycle using a mild detergent before tumble drying on a low heat. As with most waterproof protectors, you're advised not to bleach, iron or dry clean it.

The "wash separately" instruction is probably my least favourite part of ownership. It's hardly difficult, but when you've already got a mountain of children's washing waiting, adding another dedicated load feels like one more chore.

That said, after washing, the protector still fitted neatly, remained smooth and didn't lose its shape. The elasticated skirt stayed stretchy, there was no obvious shrinkage and the surface continued to feel soft rather than stiff.

It's softness is apparent as soon as you open the box

Does Simba’s cooling mattress protector actually help with cooling? 

This is really the reason most people will choose the Tencel version over Simba's cheaper Bamboo protector. Simba says the Tencel surface is breathable, moisture-wicking and naturally temperature regulating. After a month of testing, I'd say those claims are fair - but it's important to set expectations.

My youngest's bedroom is consistently the warmest room in our house, so he was a good real-world tester. If any child was going to notice a mattress protector trapping heat, it would probably have been him.

What I found wasn't dramatic cooling. The protector didn't make the bed feel cold when he climbed in and it certainly didn't overcome a hot bedroom during warm weather. Instead, it simply avoided making things worse.

Some waterproof protectors create a sealed-in feeling that leaves children sweaty by morning. The Simba protector never felt like that. The Tencel surface remained comfortable, breathable and noticeably less clammy than many waterproof protectors I've used previously. If your child naturally sleeps warm (or has the warmest bedroom like mine), every little improvement helps.

Is the Simba TripleShield Tencel Cool Mattress Protector waterproof?

Yes. According to Simba, the TripleShield Tencel Cool Mattress Protector meets BS EN ISO 20811 waterproof testing standards and has been tested to withstand water pressure exceeding 1,500mm.

Laboratory testing is one thing, but I also wanted to see how it coped with everyday family life. Because this protector was on my youngest son's bed rather than my eldest's, we didn't have any night-time accidents to test it with. Just a cup of spilled milk before bedtime. 

Thankfully, the liquid remained on the surface long enough to be wiped away, giving me confidence that the waterproof layer would protect against the sort of everyday spills and accidents most families encounter.

The elasticated edge secures the protector and has Simba's branding on

Is the Simba TripleShield Tencel Cool Mattress Protector noisy to sleep on? 

Thankfully, no. If you've ever slept on an older waterproof protector, you'll probably remember the distinctive crackling noise every time somebody rolled over. This isn't like that.

Throughout 30 nights of testing, I never noticed any obvious rustling beneath the fitted sheet. Even when my youngest settled in for sleep each night, the protector stayed quiet. Though, it’s probably an unfair test using my youngest DC as he is like a statue while sleeping. 

Simba Tencel protector: will it fit deep mattresses?

The elasticated skirt is designed to fit mattresses up to 40cm deep. On our DC’s mattress, which is shallower than that, it fitted securely with plenty of material left underneath to keep everything anchored in place.

Throughout the month, I never found myself wrestling elastic corners back underneath the mattress or waking up to half the protector having escaped overnight.

If you've got a particularly deep mattress combined with a topper, I'd still recommend measuring first, but for most family beds the 40cm depth should be more than generous enough.

The depth of the protector is 40cm so will suit deeper mattresses

Is it worth the money for a child’s bed?

For me, yes. If you’re buying for an adult bed where spills are rare, you might reasonably decide that a cheaper protector is enough. But for a child’s bed, especially one where drink spills happen occasionally, the Simba makes more sense.

The protector is more expensive than basic options, but it’s protecting the thing underneath. In our youngest child’s case, this is a Simba mattress, so keeping moisture away from it was a priority. Mattresses are expensive, awkward to clean (even with the help of my Hoover HMC5 mattress vacuum cleaner) and they’re not the sort of thing you want to replace because of a few accidents.

A good waterproof protector is not exciting. Nobody is unwrapping this on Christmas morning with tears in their eyes. But after 30 nights, three washes and a spill test, I can say it’s earned its place on the bed.

Simba’s Tencel Cool vs Bamboo mattress protectors

The closest comparison is Simba’s own TripleShield Bamboo Mattress Protector. It’s cheaper, starting from £49 for a single, and offers the same waterproof TripleShield protection and 40cm depth.

The Tencel Cool version starts from £59 and is positioned as the cooler, softer option. I’d choose the Bamboo for a spare or guest bed, but the Tencel Cool for a main bed, child’s bed or hot sleeper where nightly comfort matters more.

Final verdict: is this the right mattress protector for you?

After a month of testing, I’ve been left impressed by the Simba TripleShield Tencel Cool Mattress Protector.

It's one of those products that succeeds by being almost invisible. Once it's on the bed, you simply stop thinking about it - which is exactly what you want from a mattress protector. It protects the mattress underneath without making the bed noisier, hotter or less comfortable.

The protector goes well with my youngest's Simba mattress

The Tencel surface won't perform miracles if your bedroom feels like a greenhouse during a summer heatwave, but it does avoid the clammy, plasticky feeling that cheaper waterproof protectors can create. For my youngest, whose bedroom is consistently the warmest in our house, that made a noticeable difference to overall comfort.

It's also reassuringly practical. The deep fitted skirt stayed firmly in place throughout testing, the waterproof layer inspired confidence during our spill test and the protector remained soft and comfortable after washing.

The biggest drawback is undoubtedly the price. Starting from £59 for a single, it's considerably more expensive than many waterproof protectors available online. If you're simply looking for something to protect a spare bed that's only used occasionally, there are cheaper alternatives that will probably do the job.

However, if you're protecting a quality mattress that's used every night - or you have a child who naturally sleeps warm - I think the extra cost is easier to justify.

About the author

Rebecca Roberts (aka Beccy) is our resident lifestyle expert with a practical focus on sleep, wellness and everyday comfort. She’s equally at home tackling frank, NSFW‑adjacent topics as she is road‑testing kitchen appliances, mattresses and vacuums that work for real parents. A former editor of LJMU’s Looprevil Press, she cut her teeth in journalism in 2010, earned a post‑grad diploma in Journalism and later led editorial at ExpatWoman in Dubai before joining Mumsnet. As a mum of two, she writes with the time‑poor, sleep‑deprived in mind - honest product reviews, realistic routines and products that make parents’ lives easier.

When she’s not at her desk, she’s probably product‑testing with her two helpers, corralling a PTA or walking her two dogs up and down country lanes.

About Mumsnet reviews

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All prices are correct at the time of writing.

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