Firmness
Firm
Type
Hybrid
Depth (cm)
26
Number of Layers
3
Trial Period (nights)
Warranty (years)
10
Price Range
£379 to £599
Best Sleeping Position(s)
Certifications
Assessed from the specification published by MattressNextDay, captured September 2026, and from regular price comparison across our UK retail partners.
If you're a hot sleeper who keeps ruling out memory foam because of the heat, this mattress is built around that exact problem. The Cooler fabric cover gives an instant cool-touch feel, and the gel-infused foam beneath is designed to draw heat away from your body through the night. Underneath, firm pocket springs move independently, which means support is targeted to where you press down rather than the whole surface dipping. It's hypoallergenic, vegan friendly, and meets the BS7177: 2008 fire safety standard. Yes, it's a straightforwardly firm feel with no plush top, but that's the point: this is aimed at people who want proper orthopaedic-style support at a price from £379.
Key Features & what's inside
- Cooler™ Fabric Cover. A cool-feel knitted fabric cover that gives an instant cooling effect the moment you lie down. It also enhances breathability, helping air move through the mattress.
- Cool Gel Memory Foam. Thick layers of memory foam infused with gel microbeads, which actively draw heat away from your body. That means the contouring comfort of memory foam without the warm, sticky feel it can sometimes have.
- Pocket Springs. Firm pocket springs, each sitting in its own fabric pocket so they compress independently. This gives targeted support and pressure relief where your body needs it, rather than a uniform push-back.
Layer details from mattressnextday.co.uk product page, September 2026.
Who's it NOT for?
This is a firm mattress, so lightweight side sleepers may find it presses on shoulders and hips rather than cushioning them. If you prefer a soft, sink-in feel, look elsewhere. And if a sleep trial matters to you, check terms carefully: the retailer listing we sourced doesn't mention one.
SleepSoul Cooler Ortho 4000 Series Pocket Gel Mattress
Across 51 reviews on MattressNextDay, owners rate it 4.8 out of 5, praising the cooling gel for regulating temperature and the firm orthopaedic support for spinal alignment.
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Is the SleepSoul Cooler Ortho 4000 firm or soft?
It's firm. The pocket springs are firm by design and the gel memory foam adds contouring rather than a soft, sinking feel. It suits back and front sleepers, and heavier bodies generally, although lightweight side sleepers may find it a little hard on pressure points.
Does the SleepSoul Cooler Ortho 4000 sleep cool?
Cooling is its main selling point. The knitted Cooler cover has an instant cool-touch feel, and the memory foam is infused with gel microbeads that draw heat away from your body. Owner reviews on MattressNextDay specifically praise how well it regulates temperature.
What sizes does the SleepSoul Cooler Ortho 4000 come in?
Eight sizes: UK Single, Small Double, Double, King and Super King, plus EU Single, EU Double and EU King. The EU options are useful if you have a continental bed frame. Prices range from £379 to £599 depending on size.
Does the SleepSoul Cooler Ortho 4000 come with a warranty or trial?
MattressNextDay lists a 10-year guarantee and free next day delivery to mainland UK, though some addresses may incur a small fee. No trial period is mentioned on that listing, so check terms with whichever retailer you buy from before ordering.
How deep is the SleepSoul Cooler Ortho 4000 mattress?
It's 26cm deep, a fairly standard depth that should suit most fitted sheets without needing extra-deep bedding. That depth accommodates the gel memory foam layers on top of the firm pocket spring unit.
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