Silentnight Healthy Growth Astro Eco Comfort Pocket Kids Small Double Mattress
The Silentnight Healthy Growth Astro is a hybrid kids' mattress built around 600 Mirapocket® springs, which means your child gets support that adjusts to their body rather than a flat, one-note surface.
- Free from foam & chemical treatments
- Zoned springs that follow their shape
- 60-night trial & 5-year guarantee
£309
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Silentnight Healthy Growth Astro Eco Comfort Pocket Kids Mattress
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Mattress details
Mattress
Silentnight Healthy Growth Astro Eco Comfort Pocket Kids Mattress
Size
Firmness
Medium
Construction
Foam
Pocket Spring
Hybrid
Eco-Friendly
Depth (cm)
24
Layers
3
Layer Details
Sleep surface
A breathable quilted sleep surface, which means the top of the mattress lets air move through rather than trapping warmth. It's a simple layer doing a simple job.
Support system
600 Mirapocket® springs providing zoned support, which Silentnight says is scientifically proven to improve spinal alignment and posture. Each spring moves independently, so support follows your child's shape as they shift about.
Comfort layer
Breathable EcoComfort Fibres™ sit in the comfort layer for cooler sleep. This is where the mattress gets its softness without using any foam.
Layer details from silentnight.co.uk product page, September 2026.
Key benefits
- A teenager-sized upgrade: The UK small double is 30cm wider than the UK single at the same length, which means a growing teenager gains real elbow room without a longer bed frame.
- Fits rooms a double won't: At 15cm narrower than a UK double, this size slots into box rooms and compact bedrooms where a 4ft 6in frame would crowd the door or wardrobe.
- Zoned support across the full width: The 600 Mirapocket springs run edge to edge, so a restless sleeper who spreads out still gets support wherever they end up on the 120cm surface.
- Breathable at any size: The EcoComfort Fibres comfort layer and quilted sleep surface let air move through, useful in the smaller, warmer rooms this size tends to end up in.
- Standard 4ft bedding: Small double is a standard UK size, so fitted sheets and frames are easy to find, and a regular double duvet drapes generously over it.
This size suits you if...
Your child or teenager has outgrown a UK single but their room can't give up the floor space a full double demands, or you're furnishing a small second bedroom that occasionally hosts two. Allow at least 2.4m x 2.8m of room and the 120cm width sits comfortably, leaving space to walk past the bed rather than squeeze around it.
Consider another size if...
Your child is still small and their room is tight, or you have space to spare. For younger children we'd recommend the UK single instead, which needs around 2.1m x 2.8m; for a shared room with space, the UK double suits better, allowing 2.6m x 2.8m.
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FAQ's
Is a small double big enough for a teenager?
Usually, yes. The UK small double gives a teenager 30cm more width than the UK single they've likely outgrown, at the same 190cm length. Very tall teenagers should note the length stays at 6ft 3in, but for most it's a comfortable step up that doesn't demand a bigger room.
Will the small double Silentnight Astro fit in a box room?
In most cases. The mattress is 120 x 190cm, and we suggest a room of at least 2.4m x 2.8m so drawers still open and the door still clears. Measure with the door swing in mind before ordering; in a genuinely tight box room, the UK single may be the safer call.
Can two people share the small double Astro occasionally?
For the odd night, yes. Two adults on 120cm is snug, but the 600 pocket springs move independently, so one person turning over disturbs the other less than a basic open coil would. As a guest bed for occasional couples it works; for two people every night, the UK double is more realistic.
What bed frame does this size need?
A standard UK small double frame, sometimes labelled 4ft or three-quarter. It's a common UK size, so frames and 4ft fitted sheets are easy to find. At 23.5cm deep, the mattress is full height, so check deep fitted sheets rather than the shallow ones sold for thin children's mattresses.
Where can I buy the Astro in a small double?
Availability shifts, so the simplest route is to compare the retailers listed on this page. The prices shown here are updated as retailers change them, which matters more than usual for a kids' mattress, where offers come and go quickly across the year.