Firmness
Medium Firm
Type
Hybrid
Depth (cm)
25
Number of Layers
4
Trial Period (nights)
100
Warranty (years)
10
Price Range
£389 to £799
Best Sleeping Position(s)
Certifications
Assessed from the specification published by Mattress Online, captured September 2026, and from regular price comparison across our UK retail partners.
The main draw is the two-tier spring system. The 2,000 mini springs near the surface give a responsive, cushioned feel and help air move through the mattress, while the 2,000 Luna Pocket springs beneath respond individually to weight and movement, which means support goes where your body actually needs it and your partner's fidgeting is less likely to wake you. Above the springs, a layer of Luna Fusion Cool Memory Foam with an open cell structure adapts around you while running cooler than standard memory foam, so hot sleepers get contouring without the usual heat build-up. Mattress Online lists a 100-night trial and a 10-year guarantee, though those are the retailer's own terms rather than the brand's.
Key Features & what's inside
- Luna Fusion Cool Memory Foam. A 2cm layer of memory foam that adapts around your body, which means gentle pressure relief where you need it. Its breathable, open cell structure lets air move through, giving a cooler, fresher feel than standard memory foam.
- Reflex Foam. Two 3cm layers of Reflex foam add cushioning for extra comfort, which means a slightly softer landing before you reach the springs. They mould to your body and help keep your spine aligned.
- Mini Pocket Springs. A layer of 2,000 mini springs gives a bouncy, comforting feel, so the mattress responds quickly when you change position. Their small size creates pockets of airflow and helps reduce motion transfer between partners.
- Luna Pocket Springs. A core of 2,000 Luna Pocket springs, each encased in its own fabric pocket. They respond individually to changes in weight and movement, which means support is distributed exactly where your body needs it.
Layer details from mattressonline.co.uk product page, September 2026.
Who's it NOT for?
If you prefer a soft, sink-in feel, this is unlikely to suit: owners describe it as firm, sometimes firmer than expected at first. It's also not the choice if you want an all-foam mattress with no bounce, as the two spring layers give it a noticeably responsive feel.
Luna 4000 Support Gel Memory Pocket Hybrid Mattress
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Is the Luna 4000 mattress firm or soft?
It's described as medium to firm. Across owner reviews it comes up as firm, sometimes a little firmer than expected out of the box, though several owners say it softens after a period of use. Lightweight side sleepers may find it slightly too firm for comfortable pressure relief.
Does the Luna 4000 really have 4000 springs?
Yes, but split across two layers: 2,000 mini pocket springs near the surface and a core of 2,000 full-size Luna Pocket springs. The retailer's specification lists the total pocket spring count as 4,000, which includes both layers rather than 4,000 main springs.
Does the Luna 4000 mattress sleep hot?
It's better equipped than many memory foam hybrids. The Luna Fusion Cool Memory Foam has an open cell structure for airflow, and the mini spring layer creates pockets of air within the mattress. Owner reviews mention good temperature regulation, so hot sleepers should find it a reasonable pick.
Does the Luna 4000 come with a trial and guarantee?
Mattress Online lists a 100-night trial and a 10-year guarantee. These are that retailer's own terms rather than the manufacturer's, so if you buy elsewhere, check what that seller offers before ordering.
How deep is the Luna 4000 mattress?
It's 25cm deep, which suits most standard fitted sheets. That depth covers the memory foam and Reflex foam comfort layers plus the two spring layers, and it's available in UK Single, Small Double, Double, King and Super King sizes.
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