Available 
SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress
from £454-£534.
£454-£534
Sizes tracked: Double, King Size, Super King
Sleep guide
What mattress firmness do I need?
Choose mattress firmness by sleep position, then compare how memory foam and pocket sprung builds can still feel different even when both are labelled firm.
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Last verified: 2026-07-21
Start with your sleep position
Side sleepers usually need more room at the shoulder and hip, so a mattress that feels too flat can feel less comfortable than one with a little more contouring. Back and front sleepers often prefer a firmer, flatter feel that keeps the body more level, but body weight, pillow height and your bed base can all change how the same mattress feels in the bedroom.
Check construction as well as the label
A firm memory foam mattress and a firm pocket sprung mattress can land very differently in feel, even before you compare price. Memory foam usually leans into closer contouring, while pocket springs tend to feel more responsive; depth, comfort layer material and support system all affect whether a mattress feels genuinely right for your setup. Orthopaedic wording can point to a firmer design, but it is not a medical promise.
Match the mattress to the frame, bedding and day-to-day fit
Depth matters because it can affect bedding, toppers and whether the mattress sits well on your bed frame. Mattress Online’s product pages also show that sizes and variants can differ between models, so it is worth checking the live listing for your size before you buy. If you already use a topper or deep fitted sheets, compare the mattress depth with those items rather than relying on the firmness label alone.
What the Mattress Online examples suggest
The shortlist here is best read as a comparison set, not a ranking. SleepSoul Space 4000 Pocket Orthopaedic Gel Mattress sits at the higher end of the group at £478-£571 and shows a 4.7/5 rating from 31 reviews, while the Bodyshape options sit lower at £189-£359 for Vitality and £167-£313 for the Ortho Memory Foam model. All three are labelled firm, all show a 100-night comfort trial on the retailer page, and the Bodyshape Ortho Memory Foam page also shows a 3-year guarantee plus 347 reviews, which gives it a much stronger visible review count than the other two.
How to shortlist with fewer regrets
If you want a firmer feel with more contouring, a memory foam option such as Bodyshape Vitality or Bodyshape Ortho Memory Foam may suit you better than a springier-feeling pocket sprung model. If you prefer a more responsive feel, SleepSoul Space 4000 gives you a different construction and a much higher price point, so the question becomes whether that extra spend matches the way you sleep and the size you need. Also compare review confidence carefully: 347 reviews on Bodyshape Ortho Memory Foam is a very different signal from 31 reviews on SleepSoul or 1 review on Bodyshape Vitality, so treat ratings as useful context rather than a verdict.
Mattresses to use as comparison examples
Available 
Bodyshape Vitality Memory Foam Ortho Mattress
from £158-£305.
£158-£305
Sizes tracked: Single, Small Double, Double, King Size, Super King
Available 
Bodyshape Ortho Memory Foam Mattress
from £199-£349.
£199-£349
Sizes tracked: Single, Small Double, Double, King Size, Super King
Retailer details used
Last checked 2026-07-21. Use this as a shopping aid rather than a substitute for the live retailer listing. Always confirm the latest price, delivery cost, stock status and product details with the retailer before buying.
Helpful next reads
Use these related mattresses guides and reviews to turn the advice into a practical shortlist.
Firmness questions
Is a firm mattress always better for support?
Not always. Support is about how well the mattress keeps you comfortably aligned, and that depends on sleep position, body weight and construction. A firm label can suit some sleepers, but a firmer feel is not automatically better for everyone.
What firmness is best for side sleepers?
Many side sleepers prefer medium to medium-firm comfort because they usually need more give around the shoulder and hip. If you are comparing the firm examples on this page, look closely at the comfort layer and whether the mattress still allows enough contouring for your build.
Should I choose memory foam or pocket sprung?
Choose memory foam if you want a closer, more body-hugging feel, or pocket sprung if you prefer a more responsive surface. The SleepSoul Space 4000 shows that even a firm pocket sprung model can use foam and gel comfort layers, so the build matters as much as the label.
Does mattress depth matter for bedding and bed frames?
Yes. Mattress Online says depth can affect suitability for bedding, toppers and bed frames, so it is worth checking the live depth before buying. That matters especially if you use deep fitted sheets, a topper or a frame with limited clearance.
Can orthopaedic wording be treated as a medical benefit?
No. Orthopaedic wording should be read as a comfort and construction cue, not as a clinical promise or treatment claim. If you are unsure which mattress suits persistent discomfort, it is better to seek advice from a qualified health professional.