Firmness
Firm
Type
Hybrid
Depth (cm)
33
Number of Layers
3
Trial Period (nights)
100
Warranty (years)
10
Price Range
£601 to £1,058
Best Sleeping Position(s)
Certifications
Assessed from the specification published by Mattress Online, captured September 2026, and from regular price comparison across our UK retail partners.
This mattress is aimed at sleepers who need firmness that lasts. The 1,200 individual pocket springs respond to each part of your body separately, which means your hips and shoulders get support where they need it rather than one uniform push-back. Above the springs, high density reflex foam adds a firm, durable comfort layer that helps keep your spine aligned. The 33cm depth gives it a substantial, hotel-style profile. Buying through MattressOnline, you get a 100-night trial and free delivery to most UK mainland locations, with next day weekday delivery available. The firm feel won't suit everyone, but if you're a heavier sleeper or simply prefer a solid surface, it's a strong fit.
Key Features & what's inside
- Knitted cover. A soft knitted finish that adds a touch of cosiness and warmth on the surface. It's designed to help with airflow and breathability too, which matters on a firmer mattress where you sleep more on top than in it.
- Reflex Foam. A layer of high density reflex foam that supports spinal alignment, which means your back stays in a healthier position through the night. It's firm and durable rather than plush, so expect a solid feel from the first night.
- Pocket Springs. 1,200 individual springs, each encased in its own cloth pocket, adapt to your movement independently. That gives personalised support to different parts of your body and helps limit motion transfer from a partner.
Layer details from mattressonline.co.uk product page, September 2026.
Who's it NOT for?
This is a firm mattress, so lightweight side sleepers will likely find it too unyielding around the shoulders and hips. If you prefer a plush, cushioned surface or a memory foam hug, look elsewhere. There's no soft or medium option, and only one retailer currently stocks it, which limits your choice of buying terms.
Kaymed Heavy Sleeper 1200 Pocket Hybrid Mattress
View all mattresses
How firm is the Kaymed Heavy Sleeper 1200?
It's rated firm, and the construction backs that up: high density reflex foam over 1,200 pocket springs. Expect a solid, supportive surface with limited sink. That suits back and front sleepers and heavier builds, although lighter side sleepers may find it a little too hard.
Does the Kaymed Heavy Sleeper 1200 come with a trial?
MattressOnline lists a 100-night trial with this mattress. That trial is the retailer's own offer rather than a Kaymed guarantee, so if you buy elsewhere in future, check the terms with that seller before ordering.
What guarantee does the Kaymed Heavy Sleeper 1200 have?
The MattressOnline listing states a 10 year guarantee. As this appears on a retailer listing rather than Kaymed's own site, it's sensible to confirm the guarantee terms with the retailer at the point of purchase.
How deep is the Kaymed Heavy Sleeper 1200 mattress?
It's 33cm deep, which is a substantial profile. Check that your fitted sheets are deep enough, as standard sheets can struggle with mattresses of this depth.
What sizes is the Kaymed Heavy Sleeper 1200 available in?
Four UK sizes: Single, Double, King and Super King. Prices range from £601 to £1,058 depending on the size you choose.
Couldn't find an answer to your question? Send us a message