Sealy PostureTech Alderney Mattress
The Sealy PostureTech Alderney Mattress combines twice-tempered PostureTech springs with a MemorySense foam layer, which means firm, responsive support with some pressure-relieving cushioning on top.
- Firm, supportive feel
- Pressure-relieving foam on top
- Edge-to-edge support across the bed
£399
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The Sealy PostureTech Alderney is a firm mattress built from twice-tempered PostureTech springs, a layer of responsive foam and a MemorySense foam layer, all under a quilted soft-touch knitted cover. It's handmade in the UK and suits sleepers who want a supportive, firm feel. It comes in a UK single, UK double, UK king and UK super king, and Dreams offers a 100-night trial.
Mattress specifications
Firmness
Firm
Type
Depth (cm)
Number of Layers
3
Trial Period (nights)
Warranty (years)
Price Range
£399 to £699
Best Sleeping Position(s)
Back Sleeping
Stomach Sleeping
Certifications
Assessed from the specification published by dreams.co.uk, captured November 2026, and from regular price comparison across our UK retail partners.
Why should you choose this mattress?
This is a firm mattress that still has some cushioning. The MemorySense layer is described as pressure-relieving and cocoons your body, so the surface isn't as unyielding as the rating suggests. Twice-tempered PostureTech springs give responsive support, and EdgeGuard edge-to-edge support means you can use more of the bed's width. It's handmade in the UK. Suits sleepers who want a firm, supportive feel, although anyone who likes a soft, sinking surface may find it too firm.
Key features & layer details
MemorySense foam layer
A pressure-relieving foam that Sealy says instantly cocoons your body. It gives the firm mattress some cushioning where you need it.
Responsive foam layer
An additional layer of responsive foam that Sealy says enhances comfort. It adds a little more padding to the feel of the mattress.
PostureTech Core Support springs
Twice-tempered PostureTech springs that provide responsive support. They give the mattress its firm, supportive base.
Layer details from dreams.co.uk product page, November 2026.
Best suited for?
Back sleepers
Twice-tempered PostureTech springs give a firm, responsive base, which means the mattress holds you up evenly when you lie flat on your back.
Couples
EdgeGuard edge-to-edge support lets you use more of the bed's width, so two people can spread out without feeling the edge give way.
Combination sleepers
Responsive springs and a responsive foam layer react as you move, which means changing position through the night feels easy rather than sticky.
Heavier sleepers
A firm feel over a twice-tempered spring core gives supportive, responsive support, while the MemorySense layer still adds some cushioning on top.
If you prefer sleeping on a soft or medium mattress, this might not be the best choice. It's rated firm, and the MemorySense and responsive foam layers add comfort without changing that rating. Lighter side sleepers who want a lot of give at the shoulders and hips may find it too unyielding.
Save on an earlier or ex-display model
Some retailers still sell the earlier version of this mattress, or ex-display and returned stock at a lower price. These are the sizes where it costs less than the current model's best price.
Sealy PostureTech Alderney Mattress
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FAQ's
How firm is the Sealy PostureTech Alderney Mattress?
It's rated firm, with a MemorySense foam layer for some cushioning. That suits sleepers who want a supportive feel, although anyone who prefers a soft or medium surface may find it too firm.
What sizes does the Sealy PostureTech Alderney Mattress come in?
It comes in a UK single, UK double, UK king and UK super king. Sealy doesn't offer a UK small single, UK small double or EU sizes, so check your bed frame before ordering.
How deep is the Sealy PostureTech Alderney Mattress?
Sealy doesn't publish a depth for this mattress. If depth matters for your bed frame or fitted sheets, check with the retailer before you order.
What is the Sealy PostureTech Alderney Mattress made of?
It uses a MemorySense foam layer, a layer of responsive foam and twice-tempered PostureTech Core Support springs. A quilted soft-touch knitted cover wraps around them, and it's handmade in the UK.
Does the Sealy PostureTech Alderney Mattress come with a trial?
Dreams offers a 100-night trial on it. That's the retailer's own offer rather than Sealy's, so check Dreams' current terms before you buy.
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