Sleepeezee ActivFlex Response 3600 Memory Mattress
Mattress
Sleepeezee ActivFlex Response 3600 Memory Mattress
Size
Firmness
Construction
Depth (cm)
33
Layers
6
Layer Details
- Soft Knitted Cover. A highly breathable knitted cover that's soft to the touch. It gives the mattress a genuinely plush finish.
- Pillow Top with Mini Comfort Springs and Staycool Gel. An additional pillow layer containing up to 1000 mini comfort springs plus Staycool gel, which means the surface actively draws heat away from your body while you sleep. This is where much of the soft, cushioned first impression comes from.
- Soft Polyester Comfort Layers. Soft polyester layers that add full-body cushioning. They soften the transition between the pillow top and the layers below.
- ActivFlex Spring Foam. An innovative layer designed to mimic the precise support and movement of pocket springs while moulding to your body like a foam. In practice, that means contouring without feeling stuck in one position.
- Staycool Gel Layer. A dedicated gel layer that manages moisture within the mattress and aids temperature regulation. A sensible inclusion, since foam layers can otherwise trap warmth.
- Pocket Springs and Mini Comfort Springs Core. The core combines full-size traditional pocket springs with mini comfort springs, 3600 pocket springs in total. This gives targeted support to key areas of your body, so heavier zones like hips get more push-back.
Layer details from mattressnextday.co.uk product page, September 2026.
- Proper space for two: At 150cm wide, each of you gets 75cm each for two people sharing, so one person shifting position doesn't drag the other along.
- Less disturbance on different schedules: If one of you gets up hours before the other, 3600 pocket springs plus the wider UK king footprint help an early exit go unnoticed.
- Length for taller sleepers: The UK king runs 200cm long, 10cm longer than the UK double, which means anyone approaching six foot stops sleeping diagonally.
- Room for pillow arrangements: During pregnancy or after surgery, when you're propping pillows and changing position through the night, the extra width absorbs all that rearranging without crowding a partner.
- Softness that needs space: A plush pillow top cradles you where you settle, and the UK king gives each sleeper their own patch of it rather than a shared dip.
This size suits you if...
You share the bed every night and a double has started to feel tight, you or your partner keep different hours and want movement to go unnoticed, or one of you is tall enough that the extra 10cm of length over a UK double genuinely matters. It also suits couples expecting broken nights ahead, whether that's a baby on the way or recovery from an operation.
Consider another size if...
Your bedroom is smaller than the 2.7m x 2.9m we suggest for a UK king. In that case we'd recommend the UK double instead, which needs at least 2.6m x 2.8m and keeps the same soft, pillow-top feel.
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Is a UK king big enough for a couple on the Sleepeezee ActivFlex Response 3600?
Comfortably, for most couples. The UK king gives 75cm each for two people sharing, and because this is a soft mattress with a deep pillow top, that personal width stops you drifting into each other's hollow. If you're both broad or simply want maximum sprawl, the UK super king adds another 30cm of width.
Will the Sleepeezee ActivFlex Response 3600 UK king suit a tall sleeper?
Yes, and length is often the quiet reason to pick this size. The UK king is 200cm long, 10cm longer than the UK double, so a sleeper around six foot no longer has feet at the very edge. Bear in mind the mattress itself is soft, so taller, heavier front sleepers may prefer a firmer model.
What room size do I need for this mattress in a UK king?
We suggest a room of at least 2.7m x 2.9m for a UK king, which leaves enough space to walk around the bed and open drawers. In a new build master bedroom, measure after allowing for wardrobes: rooms that look generous empty can feel tight once furniture goes in. Anything smaller and the UK double is the safer choice.
Does a UK king help with partner disturbance on this mattress?
It helps a good deal. The 3600 pocket springs respond individually, so movement stays localised, and the UK king's 150cm width means an early riser can slip out from their own side rather than clambering past you. If one of you works shifts, the combination of wider footprint and isolated springs is exactly what you're paying for.
How do I find the best price on the ActivFlex Response 3600 in a UK king?
Compare the retailers listed on this page. The prices shown here are updated as retailers change them, so check back before you buy: mattress pricing moves often, and larger sizes like the UK king are the ones most likely to appear in seasonal promotions.