Hypnos Cawthorne Extra Firm Single 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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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
- Leaves the floor usable: We suggest a room of at least 2.1m x 2.8m for a UK single, which means a desk or wardrobe can sit alongside the bed without a squeeze.
- A flat surface for one back sleeper: The extra firm rating gives a solo back sleeper a steady, level surface with very little give at the hips.
- A secure edge on a narrow bed: Firmer outer springs reinforce the sides, which matters on a 3ft wide bed where you are never far from the edge.
- Check raised frames first: At 26cm deep, confirm the bunk, cabin or mid sleeper maker's maximum mattress depth, because a deeper mattress reduces how far the guard rail rises above it.
- Flexible guest space: Two UK singles side by side let a spare room sleep two friends separately, although guests used to a softer bed may find the extra firm feel unyielding.
This size suits you if...
You sleep alone and mostly on your back, and you want a bed with very little give. It also fits well if you are furnishing a teenager's room, a study that doubles as guest space, or a loft conversion where a narrow bed keeps the floor clear.
Consider another size if...
You want more room to spread out than a 90cm wide bed allows. We'd recommend the UK small double instead, which is 30cm wider; we suggest at least 2.4m x 2.8m for it.
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FAQ's
Will the Hypnos Cawthorne Extra Firm UK single fit a bunk bed?
The UK single measures 90 x 190cm, the standard footprint for most bunk and cabin frames. The catch is depth: at 26cm, it may exceed the maximum mattress depth some raised frames allow. Check the frame maker's guidance before buying, since the guard rail needs to sit well above the sleeping surface.
What size room do I need for a UK single Hypnos Cawthorne Extra Firm?
We suggest allowing at least 2.1m x 2.8m. The mattress itself is 3ft x 6ft 3in, so it sits comfortably in a box room or under a sloping loft ceiling, with space left for a desk or wardrobe.
Is the Hypnos Cawthorne Extra Firm single mattress suitable for a child?
It depends on the child. The extra firm rating gives very little give at the shoulders and hips, so lighter sleepers and side sleepers may find it uncomfortable. A heavier teenager who sleeps on their back is a better match than a small child who sleeps curled up.
What bedding fits a UK single Hypnos Cawthorne Extra Firm?
Standard single sheets and a single duvet, which measures 135 x 200cm, will fit. As the mattress is 26cm deep, check that your fitted sheet has deep enough pockets to tuck under comfortably.
Should I get the Hypnos Cawthorne Extra Firm in a UK single or UK small double?
The UK single is 30cm narrower than the UK small double, and both are the same length. If floor space is tight, the UK single suits a room of at least 2.1m x 2.8m. For an adult who wants more width, we suggest at least 2.4m x 2.8m for the UK small double.