SleepSoul Space 4000 Orthopaedic CoolGel Mattress
Mattress
SleepSoul Space 4000 Orthopaedic CoolGel Mattress
Size
Firmness
Construction
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.
- Room left for the rest of your furniture: At 4ft 6in x 6ft 3in, the UK double leaves space for a bedside table each side, which a UK king often squeezes out of an average master bedroom.
- The award applies to this size: The Which? Best Buy from January 2026 was given in the double mattresses category, so the UK double is the version that recognition speaks to directly.
- Less disturbance in a closer space: Sharing 67.5cm each means you sleep nearer your partner, and the independently moving pocket springs help stop their turns rolling across to your side.
- Cooler when you're side by side: Two bodies on a UK double generate more shared warmth than on wider sizes, and the CoolGel foam layer is designed to limit that heat building up.
- A sensible pick for a guest room: If couples stay a few nights a year, the UK double gives them proper shared support without the spare room turning into wall-to-wall mattress.
This size suits you if...
You share the bed with a partner and your bedroom is closer to the typical UK size than a spacious new build master suite. You also want space for bedside tables on both sides, or you're kitting out a spare room for visiting couples.
Consider another size if...
Either of you is a restless or broad sleeper and 67.5cm each already feels cramped. We'd recommend the UK king instead, provided your room is at least 2.7m x 2.9m.
Similar Mattresses in This Price Range
Did you know? On Mattress Unboxed we have over 1,000 different mattresses to suit all types of sleepers. View all mattresses.
How much space does each person get on a SleepSoul Space 4000 UK double?
Two people sharing the UK double get 67.5cm of width each. That works for most couples who sleep fairly still. If you'd like more elbow room, the UK king gives 75cm each, so on the UK double you each have 7.5cm less than on the UK king.
Will a SleepSoul Space 4000 UK double fit my bedroom with bedside tables?
We suggest a room of at least 2.6m x 2.8m for a UK double. Around 3m x 3m is the comfortable norm if you want a bedside table either side and easy access around the bed. In a smaller second bedroom, measure where the wardrobe and drawers will open before you buy.
Which size of the SleepSoul Space 4000 has a Which? Best Buy?
The Which? Best Buy award from January 2026 was given in the double mattresses category. That makes the UK double the size the award relates to most directly. The UK king and UK super king share the same construction, but the award wasn't given in their size categories.
Is it worth sizing up from the SleepSoul Space 4000 UK double to the UK king?
The UK king is 15cm wider and 10cm longer than the UK double. That extra room helps restless couples and taller sleepers. We suggest at least 2.7m x 2.9m for a UK king, though. If your room falls short of that, the UK double is the better fit.
Is the SleepSoul Space 4000 UK double long enough if you're tall?
The UK double is 190cm long, which is 6ft 3in. That suits most adults. If either of you is tall enough for your feet to reach the end, the UK king and UK super king are both 10cm longer than the UK double.