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.
- Genuine stretching room for one: At 120cm wide, it's 30cm wider than the UK single, which means a solo sleeper can shift, sprawl and starfish without an elbow ever finding the edge.
- A soft mattress that fits the small room: Plush, hotel-style comfort usually arrives in bigger sizes; this one drops the pillow-top feel into rooms of just 2.4m x 2.8m, our suggested minimum.
- The full spring count, not a reduced version: You still get the complete 3600-spring core with mini comfort springs, so the targeted push-back under hips and shoulders isn't diluted by the smaller footprint.
- Cooling that matters more in tight spaces: Compact bedrooms warm up quickly, and the Staycool gel in both the pillow top and its own layer helps the surface shed heat rather than store it.
- Easy to dress: 4ft is a standard UK size, so small double fitted sheets and frames are simple to find, although the 33cm depth means you'll want deep-pocket sheets.
This size suits you if...
You sleep alone and have outgrown a single but can't spare the width a standard double demands, or you're furnishing a box room, loft conversion or guest room where every centimetre beside the bed counts. It also suits a teenager moving up from a single in a bedroom that can't lose the floor space, since the soft, cushioned feel works well for lighter sleepers.
Consider another size if...
You share the bed every night, because 120cm gets tight for two adults on a soft surface where you both settle into the pillow top. We'd recommend the UK double instead; it's 15cm wider, and we suggest a room of at least 2.6m x 2.8m for it.
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What are the dimensions of the Sleepeezee ActivFlex Response 3600 small double?
The UK small double measures 120 x 190cm, or 4ft x 6ft 3in. It's 30cm wider than the UK single and 15cm narrower than the UK double, with the same 190cm length as both. Bear in mind the mattress itself is 33cm deep, so it sits noticeably tall on the frame.
Will a small double ActivFlex Response 3600 fit in a box room?
Usually, yes. We suggest a room of at least 2.4m x 2.8m for a UK small double, which leaves enough clearance to walk round the bed and open the door. Measure with the frame in mind rather than the mattress alone, since headboards and side rails add several centimetres to the footprint.
Can a couple sleep on the small double ActivFlex Response 3600?
For occasional nights, yes, which makes it a sensible guest room choice. As an every-night bed for two it's a squeeze: 120cm is tight for adults side by side, and because this is a soft mattress with a built-in pillow top, you'll both settle towards each other. Regular sharers would be happier on the UK double.
What bedding fits the small double version of this mattress?
You'll need small double (4ft) fitted sheets, and given this mattress is 33cm deep, choose deep or extra-deep pockets so the corners stay put. A standard double duvet works well on a small double, with a generous drape over each side, so you only need size-specific shopping for the sheets.
Should I get the ActivFlex Response 3600 in a small double or a double?
It comes down to the room and who's sleeping. The UK small double is 15cm narrower than the UK double, and that margin can decide whether a door still clears or a wardrobe still opens. Sleeping solo in a compact room, take the small double; sharing regularly, the UK double is the better call, with a suggested room of at least 2.6m x 2.8m.