Firmness
Extra Firm
Type
Foam
Depth (cm)
Number of Layers
Trial Period (nights)
60
Warranty (years)
Price Range
£1,044 to £1,810
Best Sleeping Position(s)
Certifications
Assessed from the specification published by Mattress Man, captured September 2026, and from regular price comparison across our UK retail partners.
Choose the Tranquility if firmness is your priority. Genuinely extra firm mattresses are relatively rare, and many that claim the label soften in practice, so a Sealy model built around its AlignSupport spring system is a sensible shortlist candidate if you need firm spinal support, perhaps on your GP's or physio's advice. The foam layers sit over the springs to take the edge off, which means support without sleeping directly on coils. Yes, the price range of £1,044 to £1,810 is a real spend, but it buys a full run of UK sizes and, if you buy through Mattressman, a 60-night trial to test that extra firm feel at home before committing.
Key Features & what's inside
Awaiting up to date specifications. Please check back later.
Who's it NOT for?
Side sleepers, especially lighter ones, are the obvious mismatch: an extra firm surface can push back at the shoulder and hip rather than cushioning them. It's also not for anyone who loves a plush, enveloping feel, or for buyers on a tighter budget, with prices starting from £1,044.65.
Sealy Tranquility Mattress
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How firm is the Sealy Tranquility mattress?
It's rated Extra Firm, the firmest end of the scale. Expect a solid, supportive surface with very little sink. That tends to suit back and front sleepers, and heavier bodies generally, but side sleepers who need pressure relief at the shoulder and hip may find it uncomfortable.
How much does the Sealy Tranquility mattress cost?
Prices range from £1,044 to £1,810 depending on size, starting from £1,044.65. It comes in UK Single, Double, King and Super King. That's a premium spend, though it reflects Sealy's AlignSupport spring system and the relative scarcity of true extra firm options.
Does the Sealy Tranquility come with a trial period?
Mattressman, the retailer currently stocking it, lists a 60-night trial. This is the retailer's own offer rather than a Sealy guarantee, so check the terms wherever you buy, as they may differ between shops.
How quickly can the Sealy Tranquility be delivered?
Mattressman offers free next day delivery on this mattress, with a transit time of 1 to 3 days. Those are the retailer's own delivery terms, so timings could vary if you purchase elsewhere.
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