Hypnos Cawthorne Extra Firm Mattress
The Hypnos Cawthorne Extra Firm Mattress has 1000 ReActive pocket springs under a wool and polyester comfort layer, which means you get very firm, level support with a little cushioning on top.
- Extra-firm feel for back sleepers
- Edges reinforced with firmer springs
- Wicks away moisture as you sleep
£605
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The Hypnos Cawthorne Extra Firm is a handmade, UK-built pocket spring mattress rated extra firm and 26cm deep. A wool and polyester comfort layer sits over 1000 individually pocketed springs, and the edge is reinforced. It suits sleepers who want a very firm bed, especially on the back. It comes in a UK single, UK small double, UK double, UK king, UK super king, UK emperor, EU double and EU king. Mattress Online offers a 100-night trial, and Hypnos gives a 5-year guarantee.
Mattress specifications
Firmness
Extra Firm
Type
Pocket Spring
Depth (cm)
26
Number of Layers
4
Trial Period (nights)
Warranty (years)
Price Range
£605 to £1,209
Best Sleeping Position(s)
Stomach Sleeping
Certifications
BS 7177
Assessed from the specification published by mattressonline.co.uk, captured November 2026, and from regular price comparison across our UK retail partners.
Why should you choose this mattress?
This is a properly firm mattress, and it's built to stay that way. The 1000 pocket springs each sit in their own fabric pocket, and a dual density fibre pad spreads pressure evenly across the spring unit. The wool and polyester layer adds some comfort without softening the extra firm feel. Firmer outer springs reinforce the edge, so sitting or sleeping near the side should feel more secure. A cotton and polyester layer is absorbent and wicks moisture away from your body. It suits back sleepers who want a flat, supportive surface, although anyone who likes to sink in will find it unyielding.
Key features & layer details
Pocket spring core
A core of 1000 ReActive springs, each enclosed in its own fabric pocket. Each spring works independently, so the support follows your body rather than moving as one block.
Dual density eOlus fibre pad
A dual density fibre pad that supports the spring unit and helps spread pressure evenly. That means your weight is shared out across the surface rather than concentrated in one spot.
Wool and polyester comfort layer
A blend of wool and polyester fibres that adds comfort and enhances the firm feel. You get a little cushioning without losing the extra firm character.
Cotton and polyester layer
An absorbent blend of cotton and polyester that wicks moisture away from your body. It helps the surface feel drier through the night.
Layer details from mattressonline.co.uk product page, November 2026.
Best suited for?
Back sleepers
The extra firm feel and 1000 pocket springs give a flat, supportive surface, which suits anyone who wants their back held level through the night.
Warm sleepers
A cotton and polyester layer is absorbent and wicks moisture away from your body, which helps the surface feel drier through the night.
Couples
Each of the 1000 springs sits in its own fabric pocket and works independently, and the reinforced edge makes sleeping near the side feel more secure.
European bed frames
The range includes EU double and EU king sizes alongside the UK sizes, so it fits continental frames without needing a workaround.
If you prefer sleeping on a soft or medium mattress, this might not be the best choice. It's rated extra firm, so there's very little give at the shoulders and hips. Side sleepers and lighter sleepers may find it uncomfortable. It's also single-sided, so you can rotate it top to toe but not flip it.
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.
Hypnos Cawthorne Extra Firm Mattress
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FAQ's
How firm is the Hypnos Cawthorne Extra Firm?
It's rated extra firm. The wool and polyester comfort layer adds some cushioning, but it's still best for sleepers who want very firm support, particularly on their back.
What sizes does the Hypnos Cawthorne Extra Firm come in?
It comes in a UK single, UK small double, UK double, UK king, UK super king and UK emperor. There's also an EU double and an EU king, which suit European-size bed frames.
How deep is the Hypnos Cawthorne Extra Firm?
It's 26cm deep. That should suit most bed frames, though check your frame's recess if it has one.
Does the Hypnos Cawthorne Extra Firm have a trial or guarantee?
Mattress Online offers a 100-night trial, which is the retailer's own offer. Hypnos provides a 5-year guarantee. Check the retailer's terms before buying, as trial conditions can vary.
Can you flip the Hypnos Cawthorne Extra Firm?
No, it's single-sided, so you shouldn't flip it. You can rotate it top to toe to help it wear evenly, which is worth doing regularly.
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