Firmness
Type
Hybrid
Depth (cm)
29
Number of Layers
3
Trial Period (nights)
Warranty (years)
5
Price Range
£839 to £1,459
Best Sleeping Position(s)
Certifications
Assessed from the specification published by MattressNextDay, captured September 2026, and from regular price comparison across our UK retail partners.
Two things stand out here. First, temperature: Geltex is a gel-infused foam built for breathability, paired with naturally breathable Tencel fibres, which means warmth is drawn away rather than trapped against you, a genuine plus for hot sleepers. Second, allergy credentials: the mattress is hypoallergenic and carries the Allergy UK Seal of Approval, so it is a sensible pick if dust mites or sensitivities disturb your sleep. Underneath, 1400 pocket springs move independently, adapting to your shape and limiting the rock and roll you'd feel from a partner turning over. Sealy is an NBF-approved manufacturer, and the mattress is vegan friendly. Yes, it starts at £839, but the build depth and certifications back that up.
Key Features & what's inside
- Geltex® Memory Foam. A gel-infused foam that cradles your body for pressure relief while staying breathable, which means you get the contouring of memory foam with less of the heat build-up. It sits at the top, so this is the feel you'll notice first.
- Tencel® Fibres. Soft, eco-friendly fibres that give the sleep surface a silky-smooth feel. They're naturally breathable, helping the mattress stay fresh and comfortable through the night.
- 1400 Pocket Springs. Each spring sits in its own fabric pocket and moves independently, which means support adjusts to your shoulders and hips rather than pushing back as one block. This also cuts down on motion transfer between partners.
Layer details from mattressnextday.co.uk product page, September 2026.
Who's it NOT for?
This is a medium firm mattress, so lightweight side sleepers may find it a little too solid to sink into properly, and anyone wanting a plush, cushioned surface should look elsewhere. Budget shoppers may also baulk at the £839 starting price, and the retailer-stated guarantee is shorter than some brands offer.
Sealy Immerse Hybrid Geltex Mattress
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How firm is the Sealy Immerse Hybrid Geltex mattress?
It's rated medium firm, a middle-of-the-road feel that suits most back and front sleepers. It offers enough give for combination sleepers too, although lighter side sleepers may find it slightly firm through the shoulders.
Is the Sealy Immerse Hybrid Geltex good for hot sleepers?
It's designed with hot sleepers in mind. The Geltex layer is a gel-infused foam built for breathability, and the Tencel fibres beneath it are naturally breathable, which means heat is less likely to build up than with traditional memory foam.
How many springs does the Sealy Immerse Hybrid Geltex have?
It contains 1400 pocket springs. Each one is housed in its own fabric pocket and works independently, so support follows the shape of your body and movement on one side of the bed is less likely to disturb the other.
What guarantee comes with the Sealy Immerse Hybrid Geltex?
MattressNextDay lists a 5-year guarantee alongside free next day delivery, with some addresses subject to a small fee. These are that retailer's stated terms, so it's sensible to confirm the guarantee and delivery details wherever you buy.
Is the Sealy Immerse Hybrid Geltex suitable for allergy sufferers?
Yes, on paper it's a strong choice. It's hypoallergenic, carries the Allergy UK Seal of Approval and is vegan friendly, while Sealy is an NBF-approved manufacturer, which gives some reassurance about the materials used inside.
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