Sealy PostureTech Alderney Double 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
£499
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Sealy PostureTech Alderney Mattress
More available sizes
Mattress details
Mattress
Sealy PostureTech Alderney Mattress
Size
Firmness
Firm
Construction
Foam
Memory Foam
Depth (cm)
Layers
3
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.
Key benefits
- Shared bed, furnished room: We suggest a room of at least 2.6m x 2.8m, so a typical main bedroom can hold this bed alongside a wardrobe and drawers without feeling crammed.
- Support right to the sides: With 67.5cm each, you'll often lie close to the edge, and Sealy's EdgeGuard edge-to-edge support is designed to keep that outer strip supportive rather than saggy.
- A firm base for both of you: Twice-tempered PostureTech springs give each partner the same firm support, while the MemorySense foam adds some cushioning at the shoulders and hips.
- Bedding is easy to find: Standard double sheets and a 200 x 200cm double duvet fit, so you can use what you already own or pick up spares almost anywhere.
- A proper bed for visiting couples: In a second bedroom, a UK double lets guests share comfortably while the room still works as a study or storage space between visits.
This size suits you if...
You share the bed with a partner and want a firm, sprung mattress in a bedroom of around 2.6m x 2.8m or more, or you're fitting out a guest room where visiting couples need a real shared bed without losing the wardrobe.
Consider another size if...
You and your partner want more than 67.5cm each and your room has space to spare. We'd recommend the UK king instead, which gives 75cm each; we suggest at least 2.7m x 2.9m for it.
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FAQ's
Is the Sealy Alderney UK double big enough for two adults?
For most couples, yes. You get 67.5cm each, which is fine if you both sleep fairly still, although it can feel tight if one of you sprawls. Sealy's EdgeGuard edge-to-edge support helps, because sleeping near the side of a UK double is common and the edges are built to stay supportive.
What size bedroom do I need for a UK double Sealy Alderney?
We suggest at least 2.6m x 2.8m. That leaves walking space around a 135 x 190cm mattress. If you want a bedside table on each side and a wardrobe you can open fully, around 3m x 3m feels comfortable rather than squeezed.
Sealy Alderney UK double or UK king: which should a couple choose?
The UK king is 15cm wider and 10cm longer, giving 75cm each, so the UK double gives you 7.5cm less each. Taller partners notice the extra length most. If your room reaches 2.7m x 2.9m, the UK king is roomier; below that, the UK double keeps the room usable.
What sheets and duvet fit a Sealy Alderney double?
Standard UK double sheets fit, and a 200 x 200cm double duvet covers it. Sealy doesn't publish a depth for this mattress, so check the retailer's stated depth against the pocket depth of any fitted sheet before you buy.
Will a Sealy Alderney double get up narrow stairs?
It measures 135 x 190cm, or 4ft 6in x 6ft 3in, so measure the tightest turn on your stairs and any landing before ordering. Turning staircases in older terraces and compact new build landings are the usual sticking points. Once you're sure it fits, compare the retailers listed on this page.