SleepSoul Space 4000 Orthopaedic CoolGel Mattress
The SleepSoul Space 4000 is a firm orthopaedic mattress that pairs pocket springs with a layer of CoolGel foam, which means you get the sturdier, supportive feel orthopaedic buyers look for without the heat that firm foam-topped mattresses sometimes trap.
- Cool gel foam prevents heat build-up
- Helps keep your spine aligned
- Pillow top eases shoulders & hips
£475
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At 38cm deep, the SleepSoul Space 4000 is a substantial mattress, with a plush pillow top sewn on to soften its firm base a little. It comes in UK Double, King and Super King. It holds a Which? Best Buy award for double mattresses from January 2026, and it's hypoallergenic and vegan friendly too.
Mattress specifications
Firmness
Firm
Type
Orthopaedic
Depth (cm)
38
Number of Layers
4
Trial Period (nights)
Warranty (years)
10
Price Range
£475 to £560
Best Sleeping Position(s)
Back Sleeping
Stomach Sleeping
Certifications
BS 7177
Assessed from the specification published by MattressNextDay, captured September 2026, and from regular price comparison across our UK retail partners.
Why should you choose this mattress?
This mattress suits you if you want firm support but worry about sleeping hot. The CoolGel foam layer is designed to prevent heat build-up, while individually pocketed springs work independently to support your spine, which means less of the roll-together you get on cheaper open-coil designs. A mini spring layer sits above the main springs for closer contouring, and the pillow top adds a softer surface feel. It's certified fire resistant to the BS7177: 2008 standard and carries a Which? Best Buy for double mattresses (January 2026). MattressNextDay lists a 10-year guarantee and free next day delivery to mainland UK, though some addresses may incur a small fee.
Key features & layer details
Pillow Top
A generous layer of plush comfort filling that moulds to your body, which means the firm mattress beneath feels a little more forgiving on shoulders and hips. It's sewn on top, so you get pressure relief without losing the supportive base.
CoolGel™ Foam
A thick layer of CoolGel foam that prevents heat build-up within the mattress while cradling your body. If you're a hot sleeper who's been put off memory foam before, this layer is doing the cooling work.
Mini Springs
A layer of smaller springs that contours more closely to your body shape than full-size springs can. This helps relieve tension at each point of contact rather than supporting you in broad zones.
Pocket Springs
Individually pocketed springs with a firm feel that work independently, targeting support where your body presses down most and helping keep your spine aligned. Because each spring moves on its own, a restless partner is less likely to disturb you.
Layer details from mattressnextday.co.uk product page, September 2026.
Best suited for?
Warm sleepers
The CoolGel foam layer is designed to prevent heat build-up, which means you get firm support without the trapped heat some foam mattresses hold.
Couples
Individually pocketed springs move independently of each other, which means a restless partner is less likely to disturb you, and Double, King and Super King sizes are available.
Back sleepers
Firm pocket springs help keep your spine aligned, while the mini spring layer above contours closely to your shape for supportive, even comfort.
Allergy sufferers
The cover is described as hypoallergenic, which makes this a sensible pick if you want bedding that is gentler on sensitive noses and skin.
Heavier sleepers
At 38cm deep with four layers and a firm pocket spring base, it offers substantial support, while the pillow top adds a softer surface feel.
This is a firm mattress, so lightweight side sleepers may find it doesn't let their shoulders and hips sink in enough, even with the pillow top. There's no Single size listed, and no trial period is mentioned on the retailer page, so it's a less comfortable choice if you want to test before committing.
Save on an earlier or ex-display model
Some retailers still sell the earlier version of this mattress, or ex-display and returned stock at a lower price. These are the sizes where it costs less than the current model's best price.
SleepSoul Space 4000 Orthopaedic CoolGel Mattress
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FAQ's
How firm is the SleepSoul Space 4000 mattress?
It's rated firm. The pocket springs have a firm feel, softened slightly by the pillow top and CoolGel foam layers above. That combination suits back sleepers and anyone wanting orthopaedic-style support, although lighter side sleepers may find it a little too firm.
Does the SleepSoul Space 4000 come with a guarantee?
MattressNextDay lists a 10-year guarantee on its product page. Because that's a retailer listing rather than the brand's own site, it's sensible to confirm the guarantee terms with whichever retailer you buy from.
Is the SleepSoul Space 4000 good for hot sleepers?
It's designed with hot sleepers in mind. The CoolGel foam layer is there specifically to prevent heat build-up within the mattress, and the sprung construction allows more airflow than an all-foam design. It also has a knitted cover.
What sizes does the SleepSoul Space 4000 come in?
It's available in UK Double, King and Super King. There's no Single option listed, which is a shame if you're buying for a child's room or a guest single.
How deep is the SleepSoul Space 4000 mattress?
It's 38cm deep, which is a genuinely substantial mattress. That extra height comes from stacking a pillow top, CoolGel foam and two spring layers. Do check your fitted sheets, as standard-depth sheets may struggle to stay on a mattress this tall.
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