Firmness
Type
Hybrid
Depth (cm)
25
Number of Layers
5
Trial Period (nights)
100
Warranty (years)
10
Price Range
£379 to £759
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.
Choose this if you want a softer-feeling hybrid at a sensible price. The 4000 springs are split into two layers: full-size Luna pocket springs for core support and mini pocket springs above them for finer pressure relief, which means less of that bouncy, disconnected feel cheaper spring mattresses can have. Side sleepers and lighter bodies tend to get on well with a soft to medium feel, as it lets shoulders and hips sink in rather than pressing back. Mattress Online, currently the sole listed retailer, offers a 100-night trial (a mattress protector purchase from them is required for eligibility) and a 10-year guarantee, which gives you a decent safety net for the money.
Key Features & what's inside
- Knitted cover. A soft knitted top designed to enhance airflow and breathability. It adds a cosy, slightly plush first impression when you lie down.
- Luna Fusion Cool Memory Foam. A 2cm layer of open cell memory foam, which means it lets heat escape more readily than standard memory foam while still moulding to your shape. It provides that gentle, cradled feel memory foam is known for.
- Reflex Foam. Two 3cm layers of supportive foam that mould to your body and help keep your spine aligned. This is the transition zone between the soft top and the springs below.
- Mini Pocket Springs. Small, individually cased springs that add a layer of fine-tuned pressure relief and reduce motion transfer, which means less disturbance when a partner shifts in the night.
- Luna Pocket Springs. Full-size steel springs sewn into individual fabric pockets, each responding independently to your weight and movement. This is the mattress's main support system, keeping your body properly aligned.
Layer details from mattressonline.co.uk product page, September 2026.
Who's it NOT for?
If you prefer a firm mattress, or you're a heavier back or stomach sleeper who needs a more solid surface to stay aligned, this soft to medium feel may let you sink too far. Owner feedback also mentions the lack of side handles, so if you rotate your mattress often, that's a slight nuisance.
Luna 4000 Plush Gel Memory Pocket Hybrid Mattress
Across 109 verified reviews on the Mattress Online product page, it scores 4.6 out of 5, with owners describing a comfortable sleep that improves after an adjustment period of a few days to two weeks. Common gripes are the absence of side handles and an initial chemical smell that fades.
View all mattresses
Is the Luna 4000 soft or firm?
It's rated soft to medium, so it sits on the gentler end of the scale. That suits side sleepers and lighter bodies well, although heavier sleepers or committed stomach sleepers may want something firmer.
How many springs does the Luna 4000 mattress have?
4000 in total: 2000 full-size Luna pocket springs for core support, topped with 2000 mini pocket springs that add pressure relief and reduce motion transfer between partners.
Does the Luna 4000 mattress come with a trial?
Mattress Online, the listed retailer, offers a 100-night trial, but only if you also buy a mattress protector from them. That condition matters, so check it before ordering if the trial is a deciding factor for you.
How deep is the Luna 4000 Plush mattress?
It's 25cm deep, a fairly standard depth for a hybrid. Most fitted sheets designed for standard or deep mattresses should fit without any trouble.
Does the Luna 4000 have a guarantee?
Yes, the retailer listing states a 10-year guarantee. As with any guarantee, it covers manufacturing faults rather than gradual softening from normal use, so keep your proof of purchase.
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