Sealy Alston Advantage Super King Mattress
The Sealy Alston Advantage comes in UK Single, Double, King and Super King.
- Soft, plush euro-top feel
- Gel layer for a cooler feel
- Twice-tempered springs for support
£866.15
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Sealy Alston Advantage Mattress
More available sizes
Last seen for £706.50 at Mattress Man on 31st October 2026
Last seen for £699 at Mattress Man on 8th November 2026
Last seen for £589 at Mattress Man on 9th October 2026
Mattress details
Mattress
Sealy Alston Advantage Mattress
Size
Firmness
Medium Soft
Construction
Open Coil Spring
Depth (cm)
Layers
3
Layer Details
Plush pillowtop (euro top)
A generous euro top gives the Alston a very soft, plush surface. If you like to sink into a cushioned feel, you'll notice it straight away.
Geltex comfort layer
A gel-infused comfort layer that is designed to relieve pressure in the areas of your body that need it most. That means softer cushioning where you press into the bed, with a cooler feel than you'd expect from a plush top.
PostureTech spring system
Sealy's own PostureTech springs, twice tempered, sit at the heart of the mattress and are designed to give lasting, deep support. Underneath the soft layers, they give your body a steady base to rest on.
Layer details from mattressman.co.uk and hafrenfurnishers.co.uk product pages, October 2026.
Key benefits
- 90cm of width each: Two people sharing get 90cm each, which means a partner who turns over all night is far enough away that you rarely feel it.
- Space for the whole household: When a child pads in at 3am, or a large dog treats the bed as routine, everyone still has a workable share of 180cm.
- The right scale for a big master: In a period property or a generous new build master, a UK king can look lost; the super king fills the space properly.
- 30cm wider than a UK king: The UK super king is 30cm wider than the UK king and the same length, so all the extra goes where couples actually need it.
- Full-length support at 200cm: At 200cm long, taller sleepers get clearance a 190cm mattress can't offer, without their feet meeting the footboard.
This size suits you if...
You share the bed every night and one of you is a genuinely restless sleeper, because at this width distance does more than any comfort layer could. Or your children or pets regularly join you and a UK king has started to feel crowded. Or you have a large master bedroom where a smaller mattress simply looks undersized.
Consider another size if...
Your bedroom is smaller than the 3m x 2.9m we suggest as a minimum for a UK super king. In that case we'd recommend the UK king instead, which needs at least 2.7m x 2.9m and is the same length.
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FAQ's
What size room do I need for the Sealy Alston Advantage super king?
We suggest a room of at least 3m x 2.9m, and that's our guidance rather than Sealy's. Around 3.5m x 3.2m feels more comfortable, leaving space to walk round both sides and open wardrobe doors. Before ordering, check the door swing and any tight landing turns, because a 180 x 200cm mattress is an awkward carry.
Is the Sealy Alston Advantage in a UK super king big enough for a couple and a child?
Usually, yes. With 90cm each for two people sharing, a child climbing in during the night still leaves everyone a reasonable share of the 180cm width. It's one of the main reasons families choose this size: on a UK double or UK king, a third small body means somebody sleeps badly.
How much bigger is the super king than the king in this mattress?
The UK super king is 30cm wider than the UK king, and the two are the same length at 200cm. All of the extra space is width, which is what matters if you're buying to escape a restless partner. The trade-off is room size: we suggest at least 3m x 2.9m for the UK super king against 2.7m x 2.9m for the UK king.
Will a super king Sealy Alston Advantage suit a restless partner?
Distance is the most reliable fix for a restless partner, and this size offers the most of it that standard UK retailers stock. At 90cm each, most turning and fidgeting happens too far away to wake you. Sealy doesn't publish detailed construction figures for this model, so the width, rather than any motion-isolation claim, is doing the work here.
Can I fit a UK super king in a loft conversion bedroom?
Often, but the slope decides everything. At 180cm wide and 200cm long, this mattress usually has to sit against the one full-height wall, so measure that wall and the usable floor beside it before buying. Check the staircase too: loft stairs tend to be narrow with a tight turn, and this is the largest standard size to manoeuvre.