SleepSoul Space 4000 Orthopaedic CoolGel King Size 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
£509
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SleepSoul Space 4000 Orthopaedic CoolGel Mattress
More available sizes
Mattress details
Mattress
SleepSoul Space 4000 Orthopaedic CoolGel Mattress
Size
Firmness
Firm
Construction
Orthopaedic
Depth (cm)
38
Layers
4
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.
Key benefits
- Room to turn without a nudge: At 75cm each for two sharing, you can change position without brushing your partner, something the UK double's 67.5cm each makes harder.
- Fewer wake-ups on split schedules: If one of you leaves hours before the other, the wider surface and independent pocket springs mean the early riser's exit is less likely to wake the other partner.
- Length for a tall partner: At 200cm long, the UK king adds 10cm over the UK double, so a partner over six foot is less likely to find their feet at the very edge.
- Cooler when two of you share: Two bodies make more warmth than one, and the CoolGel foam layer is designed to prevent heat build-up, which helps on a shared UK king.
- Space for pregnancy pillows: During pregnancy and the months after, the extra width leaves room for a support pillow on one side without pushing your partner towards the edge.
This size suits you if...
You share the bed every night and keep bumping elbows on a UK double, one of you is tall enough to find 190cm a little short, or your hours don't line up and you want to stop waking each other.
Consider another size if...
Your bedroom falls under our suggested 2.7m x 2.9m once wardrobes are in. We'd recommend the UK double instead, and we suggest at least 2.6m x 2.8m for it.
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FAQ's
Is the SleepSoul Space 4000 UK king big enough for two adults?
For most couples, yes. The UK king gives 75cm each for two sharing, 7.5cm more each than the UK double. If you both sprawl, the UK super king gives 90cm each, although it needs a larger room.
SleepSoul Space 4000 king or super king if my partner keeps waking me?
The UK super king is 30cm wider than the UK king, so there's more distance between you. It needs at least 3m x 2.9m, though. If your room is tighter, the UK king still helps, and its pocket springs move independently to limit disturbance.
Is the SleepSoul Space 4000 UK king long enough for someone over 6ft?
The UK king measures 5ft x 6ft 6in, or 150 x 200cm. That's 10cm longer than the UK double and the same length as the UK super king, so a tall sleeper gains the extra length without needing the widest size.
What size bedroom do I need for a SleepSoul Space 4000 UK king?
We suggest at least 2.7m x 2.9m, with 3.2m x 3.2m comfortable. New build master bedrooms can feel smaller than their floor plans once wardrobes go in, so measure with furniture in place before you order.
Is a SleepSoul Space 4000 UK king worth it if our dog sleeps on the bed?
It helps. A dog tends to claim more than its share, and on a UK double that leaves two adults with 67.5cm each before the dog arrives. The UK king starts you at 75cm each, which gives a little more slack.