Silentnight Healthy Growth Astro Eco 600 Pocket Small Double Mattress
The Silentnight Healthy Growth Astro Eco 600 Pocket is a medium-feel pocket spring mattress designed for growing sleepers, available in UK Single and UK Small Double.
- Support that adapts as they grow
- Breathable fibres help kids sleep cooler
- 60-night trial & 5-year guarantee
£274
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Silentnight Healthy Growth Astro Eco 600 Pocket Mattress
More available sizes
Last seen for £329 at Mattress Online on 25th June 2026
Mattress details
Mattress
Silentnight Healthy Growth Astro Eco 600 Pocket Mattress
Size
Firmness
Medium
Construction
Pocket Spring
Eco-Friendly
Depth (cm)
24
Layers
3
Layer Details
Sleep surface
A breathable quilted sleep surface, which means a soft first point of contact that lets air circulate rather than trapping warmth.
Support system
600 Mirapocket springs providing zoned support, which Silentnight states is scientifically proven to improve spinal alignment and posture. Each spring moves independently, so support follows the body's shape.
Comfort layer
Breathable EcoComfort Fibres designed for cooler sleep, helpful if your child tends to overheat at night.
Layer details from silentnight.co.uk product page, September 2026.
Key benefits
- Room for a growing teenager: The UK small double is 30cm wider than the UK single, which means a teenager can stretch out without you needing a full-size double.
- Fits rooms a double would crowd: At 15cm narrower than a UK double, it can slot into a box room or loft conversion where the door or wardrobe would otherwise become a problem.
- Same length as the single: The UK small double and the UK single share the same 190cm length, so upgrading widthways doesn't force the bed further into the room.
- Zoned support at this width: The 600 Mirapocket springs move independently across the wider surface, so support follows a growing body wherever they end up sleeping.
- Standard 4ft bedding: Small double is a standard UK size, which means fitted sheets and frames are easy to find, with a standard double duvet on top.
This size suits you if...
Your teenager has outgrown a UK single but their bedroom can't take a full double, or you're furnishing a small second bedroom in a rental or holiday let and want something a solo guest can spread out on. It also suits a loft room or box room where 15cm of saved width decides whether the layout works at all.
Consider another size if...
You're buying for a younger child in a compact room, or the extra 30cm of width would eat floor space they still need to play in. We'd recommend the UK single instead, which needs a room of at least 2.1m x 2.8m.
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FAQ's
Is a small double too big for a child's bedroom?
It depends on the room, not the child. The UK small double is 120cm wide, and we suggest a room of at least 2.4m x 2.8m to fit it comfortably. If the room is smaller than that, or your child still needs floor space to play, the UK single at 90cm wide is the better call.
Is the Silentnight Astro Eco 600 small double suitable for a teenager?
Yes, and it's arguably the size this mattress makes most sense in for older children. The UK small double gives a teenager 30cm more width than a UK single, while the medium-feel Mirapocket springs offer zoned support designed around spinal alignment during growth. The 190cm length matches a single, so tall teens gain width rather than legroom.
Can the Astro Eco 600 small double work in a guest room?
For occasional use, yes. A UK small double lets couples share for the odd night, and a solo guest gets plenty of room. Bear in mind this is a children's mattress with a medium feel and a slightly shallower 23.5cm depth, so it suits a spare room used now and then rather than nightly adult sharing.
What's the size difference between the Astro Eco 600 in single and small double?
The UK small double is 30cm wider than the UK single, and both are the same 190cm length. In room terms, we suggest at least 2.4m x 2.8m for the UK small double and 2.1m x 2.8m for the UK single, so the wider size asks for a modestly bigger room rather than a different one.
Where can I buy the Astro Eco 600 in a UK small double?
Compare the retailers listed on this page. The prices shown here are updated as retailers change them, so it's worth checking back rather than assuming today's price holds. This mattress only comes in UK single and UK small double, so if stock is thin there's no larger size to fall back on.