Last seen for £939 at Silentnight on 2nd September 2026
Silentnight Just Sleep Serene King Size Mattress
The Silentnight Just Sleep Serene comes from Silentnight, one of the UK's best-known mattress brands, and is available in UK Double, UK King and UK Super King.
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
More available sizes
Last seen for £1,049 at Silentnight on 2nd September 2026
Last seen for £939 at Silentnight on 2nd September 2026
Last seen for £869 at Silentnight on 2nd September 2026
Mattress details
Mattress
Silentnight Just Sleep Serene Mattress
Size
Firmness
Construction
Depth (cm)
Layers
Layer Details
Key benefits
- Proper space for two: At 75cm each for two people sharing, you can turn over without negotiating, which makes a real difference if one of you is a restless sleeper.
- 15cm wider than a UK double: The UK king is 15cm wider than the UK double, which means less partner disturbance when one of you gets up hours before the other.
- Extra length for taller sleepers: The UK king is 10cm longer than the UK double, so anyone approaching six foot keeps their feet on the mattress rather than hanging off it.
- Room to shift position: Pillows propped for pregnancy, a recovering knee, or a dog claiming a corner: the extra width absorbs these without pushing anyone to the edge.
- Standard bedding, wide choice: King is one of the most common UK sizes, so sheets and duvets for this Silentnight are easy to find and rarely carry a premium.
This size suits you if...
You share the bed every night and a UK double has started to feel cramped, especially if one of you wakes early or gets up in the night. It also suits taller sleepers who want the 200cm length, and anyone whose sleep involves a lot of repositioning, from pregnancy pillows to recovery after surgery, where space to move is the point.
Consider another size if...
Your bedroom is smaller than our suggested minimum of 2.7m x 2.9m for a UK king. In that case we'd recommend the UK double instead, which needs at least 2.6m x 2.8m and still sleeps two comfortably.
Similar Mattresses in This Price Range
Did you know? On Mattress Unboxed we have over 1,000 different mattresses to suit all types of sleepers. View all mattresses.
FAQ's
Is a UK king big enough for a couple and a dog?
Usually, yes. With 75cm each for two people sharing, a dog settling at the foot or along one side takes a share you can spare. If the dog is large and sleeps between you every night, the UK super king, which is 30cm wider than the UK king, is the more comfortable long-term answer.
Will the Silentnight Just Sleep Serene UK king fit my bedroom?
We suggest a room of at least 2.7m x 2.9m for a UK king, with 3.2m x 3.2m feeling comfortable. New build master bedrooms can be tighter than they look once fitted wardrobes go in, so measure the clear floor space, and leave walking room on both sides of the bed.
Is a UK king long enough for someone over six foot?
At 200cm, or 5ft x 6ft 6in overall, the UK king gives a tall sleeper meaningful headroom. The UK king is 10cm longer than the UK double, and for many taller people that length, rather than the width, is the real reason to size up. The UK super king is the same length, so going wider adds no height.
Should we choose the UK king or the UK super king of this mattress?
The UK king suits most couples: noticeably more space than a UK double without demanding a large room. The UK king is 30cm narrower than the UK super king, so if you have a room of at least 3m x 2.9m and want maximum separation, perhaps with children or pets joining you, the UK super king is the better pick.
Does the UK king reduce partner disturbance?
Size helps: with 75cm each for two people sharing, one partner slipping out early for work disturbs the other less than in a UK double. Silentnight publishes limited construction detail for the Just Sleep Serene, so we can't say how well it isolates motion; check the retailer listing on this page for the latest specification.