Hypnos Cawthorne Extra Firm Small Double 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
£729
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Hypnos Cawthorne Extra Firm Mattress
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Mattress details
Mattress
Hypnos Cawthorne Extra Firm Mattress
Size
Firmness
Extra Firm
Construction
Pocket Spring
Wool
Depth (cm)
26
Layers
4
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.
Key benefits
- Room to sprawl on your own: At 30cm wider than a UK single, a teenager who has outgrown a single bed, or any solo adult, can turn over freely without meeting the edge.
- Fits a compact bedroom: We suggest a room of at least 2.4m x 2.8m, so a box room or small loft conversion can take a 4ft bed and still leave you walking space.
- More usable width at the sides: Firmer outer springs reinforce the edge, which means you can sit or sleep near the side of the 120cm width and feel secure rather than perched.
- Calmer for occasional sharers: Each of the 1000 springs moves on its own, so when guests share for a night or two, one person turning over should disturb the other less.
- Bedding is easy to buy: As a standard 4ft UK size, it takes small double fitted sheets and a standard double duvet, with no hunting for specialist bedding.
This size suits you if...
You sleep alone and want more room than a UK single gives, your bedroom is too compact for a UK double, or you're setting up a guest room where couples stay only now and then.
Consider another size if...
You share the bed every night with a partner. We'd recommend the UK double instead, which gives 67.5cm each for two sharing; we suggest at least 2.6m x 2.8m for the UK double.
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FAQ's
Is the Hypnos Cawthorne Extra Firm small double big enough for two?
For a guest couple staying a night or two, yes. For nightly sharing it's a squeeze, and the very firm surface gives little cushioning when you're pressed close. If two of you sleep together every night, the UK double gives 67.5cm each, and we suggest at least 2.6m x 2.8m for the UK double.
What size room do I need for a UK small double Hypnos Cawthorne?
We suggest at least 2.4m x 2.8m for a UK small double. In a loft conversion, measure where the ceiling is high enough to stand, as well as the floor, since you need headroom on the side you get in and out.
How much wider is the Hypnos Cawthorne small double than the single?
The UK small double is 30cm wider than the UK single, and both are the same length. That extra width is where the difference lies, giving a solo sleeper real room to stretch. If space is very tight, we suggest at least 2.1m x 2.8m for the UK single.
What bedding fits a UK small double mattress?
Look for fitted sheets labelled small double or 4ft, paired with a standard double duvet, which gives a little overhang on each side. The Cawthorne Extra Firm is 26cm deep, so check the sheet's pocket depth suits that before you buy.
Is a small double extra firm mattress a good choice for a teenager?
A UK small double suits a teenager moving on from a single when the bedroom can't spare much more floor. At 4ft x 6ft 3in, it gives room to grow sideways. The extra firm feel suits back sleepers, but lighter teenagers or side sleepers may find it uncomfortable at the shoulders and hips.