Sleepeezee ActivFlex Response 3600 Memory Double Mattress
The Sleepeezee ActivFlex Response 3600 is a soft memory mattress that pairs 3600 pocket springs with foam and cooling gel layers.
- Soft feel with real spring support
- Cooling gel in two layers
- Made in the UK, vegan-friendly
£1,099
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Sleepeezee ActivFlex Response 3600 Memory Mattress
More available sizes
Mattress details
Mattress
Sleepeezee ActivFlex Response 3600 Memory Mattress
Size
Firmness
Soft
Construction
Memory Foam
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.
Key benefits
- The traditional shared size: At 135 x 190cm, the UK double is the long-established size for two, giving 67.5cm each for two people sharing.
- Fits rooms a king would crowd: We suggest at least 2.6m x 2.8m, which leaves most typical UK bedrooms space for bedside tables on both sides rather than squeezing past the footboard.
- Soft comfort with support for two: The pillow top with Staycool gel sits over full-size pocket springs, which means each of you gets contouring without disturbing the other's side.
- Cooling matters more when sharing: Two bodies generate more warmth than one, so the dedicated Staycool gel layer earns particular relevance in this shared size.
- Easy to dress: Standard double sheets and a 200 x 200cm duvet fit, both stocked everywhere at every price point.
This size suits you if...
You're a couple after a soft, hotel-style bed in a typical UK bedroom, where a bigger size would dominate the floor. It also suits a solo sleeper who likes to spread out, or shares the mattress with a cat or dog that claims a corner most nights. If your room measures at least 2.6m x 2.8m, this size should work.
Consider another size if...
You and your partner both toss and turn, or one of you is broad-shouldered, and 67.5cm each for two people sharing feels tight. We'd recommend the UK king instead, which is 15cm wider and 10cm longer; allow at least 2.7m x 2.9m for it.
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FAQ's
Is the Sleepeezee ActivFlex Response 3600 in a UK double big enough for a couple?
For most couples, yes. The UK double gives 67.5cm each for two people sharing, and the pocket spring core means movement on one side is less likely to travel across the bed. That said, if either of you is tall or you both sleep starfish-style, the UK king's extra 15cm of width and 10cm of length is a meaningful upgrade.
What room size do I need for the ActivFlex Response 3600 in a UK double?
We suggest at least 2.6m x 2.8m, with around 3m x 3m the comfortable norm. That allows walking space on both sides and, in most rooms, bedside tables too. These figures are our own guidance rather than Sleepeezee's, so measure your room before ordering, especially in older properties with chimney breasts or awkward alcoves.
Should I choose the ActivFlex Response 3600 in a UK double or a UK king?
The UK double is 15cm narrower and 10cm shorter than the UK king, so the choice usually comes down to your room. If you have at least 2.7m x 2.9m and share the bed nightly, the UK king gives welcome extra elbow room. In a smaller bedroom, the UK double keeps space for wardrobes and drawers.
Will the UK double version fit up a narrow staircase?
It's a fair concern: at 33cm deep with a built-in pillow top, this is a substantial mattress, and the UK double's 135cm width needs turning room on tight landings and older terraced staircases. Sleepeezee doesn't publish a weight for this size, so measure any awkward turns and check the retailer's delivery guidance before you order.
Is a UK double ActivFlex Response 3600 a good guest room choice?
It's a generous option for a guest room that hosts visiting couples, since the 135 x 190cm footprint sleeps two while leaving space for a wardrobe and drawers. The soft, pillow-top feel divides opinion more than a medium would, though, so it's a slightly bolder pick for guests than for a bed you've chosen for yourself.