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SleepeezeeActivflex Response 1600

Hybrid
Cold

£1,049View retailers

Test score

Lowest available price

£849Mattressnextday

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The Sleepeezee Activeflex Response 1600 mattress is ‘expertly designed for those seeking firmer support’, according to the manufacturer. It includes layers of cooling gel and spring foam designed to complement its pocket springs, adapting to your body shape and movements during sleep. But how do its levels of comfort and support compare with other mattresses? We tested it to find out – read the full review for our expert verdict.

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KEY TEST RESULTS
Body support overall
Durability
Stability

Jun 2026Last checked by Which?
Apr 2025First reviewed by Which?
Sept 2024Released

The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.

Compression testing machine applying pressure to a white mattress on a wooden table in a light-colored room.

How we test mattresses

17 Apr 2026

Performance

Overall
Body support for back sleepers
Body support for side sleepers
Body support for front sleepers
Body support overall
Breathability
Turning on mattress
Stability
Pressure distribution

How we test performance

We rate overall mattress performance by combining the results of six individual tests. We measure how well the mattress keeps your body in a natural position when you're lying on your side or back and combine these into an overall body support score. We also rate how easy it is to roll over on the mattress and how breathable it is – more breathable mattresses will not get damp with sweat. Finally, we measure stability to assess how much you'll notice the mattress moving when your partner turns on it - good mattresses are more stable.

Durability

Overall
Change in height
Change in firmness
Change in body support lying on back
Change in body support lying on side
Change in body support lying on front
Damage

How we test durability

To test how durable mattresses are, we simulate years of use by rolling a heavy barrel over them thousands of times. We then assess each mattress for damage and change in height, firmness and body support to see how well they stand the test of time. Good mattresses will stay the same as when you first bought them. The overall durability score is a combination of the individual ratings. Change in height shows how much the mattress sagged in our durability test and change in firmness measures if the mattress got harder or softer. Change in body support indicates whether the mattress offers the same level of support after years of use. Finally, we rate whether or not the mattress was damaged after our durability tests.

Ease of use

How we test ease of use

Most mattresses need turning over or rotating from time to time, so we rate how easy it is to move and turn the mattress by considering factors like weight and whether there are any handles.

Build quality

How we test build quality

How well constructed the mattress is.

Brand comfort

How we test brand comfort

This is not a comfort score for this individual mattress, and does not contribute to the overall test score. We cannot test mattresses for comfort because everyone has a different opinion on what is comfortable. In October 2023, we asked 3,530 Which? members in an online survey, who own a mattress from this brand, to rate it for comfort. The star rating shows whether the general consensus was positive or not, and can be used as a guide to this brand as a whole. Go to our mattress brand guides for more information, and bear in mind that you should make every effort to try a mattress before you buy.

Sustainability overall

Overall
Carbon footprint
Recyclability

General
Type	Hybrid
Size	Double
Softness	5
Memory effect	Medium
Warmth	Cold
Removable mattress cover	No
Weight	39kg
Length	192cm
Width	138cm
Depth	26cm
Testing information	This model was tested after we improved our mattress tests in November 2022, so the results are not directly comparable with models tested before that date.

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SleepeezeeActivflex Response 1600

Lowest available price