Sleepeezee ActivFlex Response 1600 Memory King Size Mattress
The Sleepeezee ActivFlex Response 1600 is a firm hybrid that pairs 1600 barrel-shaped pocket springs with memory-style foams, which means you get precise, targeted support with a gentle cushioned surface on top.
- Firm support with a softer top
- Cooling gel helps regulate temperature
- Hypoallergenic & vegan-friendly
£899
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Sleepeezee ActivFlex Response 1600 Memory Mattress
More available sizes
Mattress details
Mattress
Sleepeezee ActivFlex Response 1600 Memory Mattress
Size
Firmness
Firm
Construction
Hybrid
Memory Foam
Depth (cm)
25
Layers
5
Layer Details
Soft Knitted Cover
A highly breathable knitted cover that's soft to the touch. It gives the mattress a genuinely luxurious finish.
Pillow Top / Comfort Layer
A soft polyester comfort layer that adds gentle cushioning, which means the surface feels welcoming rather than hard. It does this without compromising the firm feel underneath.
Staycool™ Gel
A deep layer of Staycool Gel that provides a consistently cooling sensation, helping to regulate your temperature. If you're a hot sleeper, this is the layer doing the work for you.
ActivFlex™ Spring Foam
A layer of spring foam that behaves like pocket springs for precise support, yet moulds to your body like foam. The result is support at every point of contact rather than pressure in a few places.
Pocket Springs Core
A core of up to 1600 barrel-shaped pocket springs delivering targeted support to key areas of your body. This is where the firm feel comes from.
Layer details from mattressnextday.co.uk product page, September 2026.
Key benefits
- Room to sleep apart, together: At 75cm each for two people sharing, you can both settle into your own space rather than negotiating the middle of the bed.
- Springs that keep movement local: The pocket spring core responds where weight lands, which means one of you getting up early is less likely to wake the other across a UK king's width.
- Length for taller sleepers: The UK king is 10cm longer than the UK double, so anyone nudging six foot gets their feet on the mattress rather than off the end.
- Cooling spread over a wider surface: The Staycool Gel layer runs across the full 150cm width, so two warm sleepers aren't fighting over one cool patch.
- Firm support at full size: The firm feel that supports heavier or back sleepers doesn't soften in a larger size, so upgrading for space costs you nothing in support.
This size suits you if...
You share the bed every night and a double has started to feel cramped, especially if one of you is a restless or firm-mattress sleeper. You keep different hours and want the width and localised spring support to slip in or out without waking your partner. Or one of you is tall and needs the 200cm length as much as the width.
Consider another size if...
Your bedroom falls short of the 2.7m x 2.9m we suggest for a UK king, or you sleep alone. We'd recommend the UK double instead, which needs at least 2.6m x 2.8m and still offers the same firm feel.
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FAQ's
Is a UK king big enough for a couple on the Sleepeezee ActivFlex Response 1600?
For most couples, yes. You get 75cm each for two people sharing, and because this is a firm mattress with a pocket spring core, you won't roll towards a soft middle. If one of you spreads out, or a dog claims the foot of the bed most nights, the UK super king is the roomier option.
Will the king size Sleepeezee ActivFlex Response 1600 stop me feeling my partner move?
It helps on two fronts. Pocket springs move independently, so motion stays close to where it starts rather than travelling across the bed, and the UK king's 150cm width puts more distance between you. If one of you gets up hours before the other, that combination makes the early exit less disruptive.
Is the UK king long enough if I'm over six foot?
At 200cm, the UK king is 10cm longer than the UK double, and that extra length is often the real reason taller sleepers upgrade. It gives someone around six foot room to stretch out without their feet hanging over the edge. The UK super king is the same length, so going wider adds no more room at the foot.
What room size do I need for this mattress in a UK king?
We suggest at least 2.7m x 2.9m, with around 3.2m x 3.2m feeling comfortable once wardrobes and bedside tables are in. New build master bedrooms can be tighter than they first appear, so measure with furniture in place. If the room falls short, the UK double needs at least 2.6m x 2.8m.
Where can I buy the Sleepeezee ActivFlex Response 1600 in a UK king?
Compare the retailers listed on this page. The prices shown here are live and updated as retailers change them, so checking back before you buy is sensible. The UK king is one of five sizes this mattress comes in, from UK single up to UK super king.