Every soft mattress evaluated with pressure mapping technology and real-world comfort trials. See our methodology
If you wake with numb shoulders, aching hips, or the urge to constantly shift position, your mattress is likely too firm for your body. We've tested 5 soft and medium-soft mattresses—from memory foam to luxury pillow tops—to find the ones that deliver genuine plush comfort without sacrificing spinal support.
This guide focuses on Soft (3) and Medium-Soft (4) mattresses, highlighted above.
Comfort & Ergonomics Specialist
Pressure relief science and side-sleeper ergonomics
Emma is a certified ergonomics consultant who specialises in comfort profiling and pressure-point analysis. She has worked with UK physiotherapy clinics to develop mattress recommendation frameworks and leads our pressure-mapping evaluations at BestMattress.uk.com.
The UK mattress market has long leaned towards firmness. For decades, the prevailing wisdom was that firmer is better—that a hard sleeping surface equals a healthy back. But modern sleep science has overturned this assumption, revealing that the ideal firmness depends entirely on your body weight, sleep position, and individual pressure sensitivity.
For many sleepers—particularly the estimated 74% of British adults who spend at least part of the night on their side—a softer mattress isn't a luxury; it's a biomechanical necessity. When you lie on your side, your body weight concentrates on two narrow points: shoulders and hips. These areas need to sink into the mattress to maintain horizontal spinal alignment. On a mattress that's too firm, they can't—and the result is pressure buildup that restricts blood flow, causes numbness, and forces you to toss and turn throughout the night.
This is where pressure relief enters the conversation. Your blood capillaries collapse at approximately 32 mmHg of external pressure—anything above this threshold starts restricting circulation. When your mattress pushes back too firmly against your shoulders or hips, it creates pressure points that exceed this threshold. Your body responds by sending "move" signals to your brain, pulling you out of deep sleep to change position. A soft mattress keeps pressure below this threshold, allowing uninterrupted blood flow and deeper, more restorative sleep.
Of course, not all soft mattresses are created equal. The worst ones sacrifice support for surface plushness, leading to spinal misalignment and morning back pain. The best soft mattresses provide a plush comfort layer for pressure relief above a firm support core for spinal alignment—giving you the cushioning you need at the surface while maintaining structural integrity deeper in the mattress.
At BestMattress.uk.com, we test every mattress with medical-grade pressure mapping equipment alongside real-world sleep trials. For this guide, our testers—including dedicated side sleepers and individuals with diagnosed shoulder and hip conditions—evaluated each mattress over multiple weeks to separate genuine comfort from showroom-floor impressions.
These mattresses deliver verified plush comfort with genuine pressure relief—ideal for side sleepers, lightweight individuals, and anyone seeking cushioned support. Each has been pressure-mapped and sleep-tested for real-world comfort.
Luxury pocket sprung with natural silk for plush comfort and elegant craftsmanship.
Ultra-soft luxury memory foam for side sleepers who love a plush, cradling feel.
Luxurious pillow-top comfort with responsive pocket springs and natural cashmere filling.
Softer Talalay latex for side sleepers seeking responsive, bouncy comfort.
Soft, plush memory foam perfect for side sleepers who love to sink into their mattress.
Soft mattresses aren't for everyone—but for the right sleepers, they can eliminate pain, improve sleep depth, and transform morning comfort.
Side sleeping concentrates roughly 60% of your body weight on just two points—shoulders and hips. Without adequate cushioning, these pressure points press hard against the mattress, restricting blood flow and causing numbness, tingling, and morning pain. A soft mattress lets these bony prominences sink gently into the comfort layers, distributing pressure evenly and keeping your spine horizontally aligned.
Body weight determines how much you compress mattress materials. Lighter individuals simply don't exert enough force to engage the comfort layers of a medium or firm mattress, meaning the mattress feels harder than its rating suggests. A soft mattress responds to lower body weight, allowing proper contouring and pressure relief that heavier sleepers achieve naturally on firmer models.
Conditions like osteoarthritis, rheumatoid arthritis, and fibromyalgia make joints hypersensitive to pressure. A firm mattress that pushes back against swollen or inflamed joints can intensify overnight pain and morning stiffness. Soft mattresses distribute body weight across a larger surface area, reducing localised pressure on affected joints while still maintaining enough support to prevent misalignment.
Even without arthritis, many people experience shoulder or hip pain that worsens overnight. This frequently stems from the mattress creating excessive pressure at these points. A soft mattress with quality comfort layers allows the shoulder to nest into the surface when side sleeping, and cushions the hip without pushing it out of alignment—addressing two of the most common mattress-related pain complaints.
Stomach sleeping on a soft mattress lets the pelvis sink deeply, creating an unhealthy arch in the lower back. This spinal hyperextension can cause significant lower back pain over time. Stomach sleepers need firm support (7-8) to keep the body level.
Greater body weight compresses soft comfort layers more aggressively, often causing "bottoming out"—sinking through the comfort layer to the firm support core beneath. This eliminates the pressure relief benefits and can create worse alignment than a properly firm mattress.
If you have specific lower back conditions that require firm support to maintain spinal curvature, a soft mattress may allow too much sinkage in the lumbar region. Consult your physiotherapist or GP about the appropriate firmness for your condition.
The comfort layer is what makes a soft mattress feel soft. Understanding these technologies helps you choose the right type of plush for your needs.
Classic body-contouring pressure relief
Memory foam (viscoelastic polyurethane) softens in response to body heat and weight, slowly conforming to your exact shape. This creates a personalised cradling effect that distributes pressure evenly across your body. Modern memory foams use open-cell structures for improved breathability compared to older, denser formulations. The slow response means you feel gently "hugged" rather than bounced.
Responsive, breathable natural softness
Talalay latex is manufactured through an aeration process that injects air into liquid latex before vulcanisation, creating a lighter, softer, and more consistent cell structure than Dunlop latex. The result is a buoyant, responsive comfort layer that contours to your body instantly—without the slow sink of memory foam. It springs back immediately when you move, making position changes effortless.
Added plush layer stitched to the mattress surface
A pillow top is an extra layer of cushioning sewn onto the top of a mattress, typically 5-10cm thick. It can contain memory foam, latex, wool, cotton, or synthetic fibres. A Euro top is similar but flush-fitted to the mattress edges for a sleeker appearance. Both add immediate surface softness without altering the core support system beneath, making them an effective way to achieve plush comfort on a supportive base.
Plush comfort with improved temperature management
Gel-infused foams combine the pressure-relieving properties of soft memory foam with gel beads or gel swirls designed to absorb and dissipate body heat. This addresses the primary drawback of soft mattresses—heat retention from deep body conforming. The gel layer creates a cooler sleep surface while maintaining the cradling comfort that side sleepers and pressure-sensitive individuals need.
Tiny springs that create adaptive softness with airflow
Micro-coils are miniature pocket springs (typically 2-4cm tall) used as a comfort layer above the main support core. Hundreds or thousands of these tiny springs respond individually to body pressure, creating a soft, adaptive surface that contours without the heat retention of foam. The spaces between coils allow air to circulate freely, making micro-coil comfort layers one of the coolest soft options available.
In our pressure mapping evaluations, the most comfortable soft mattresses combined multiple comfort technologies rather than relying on a single material. The ideal combination we've found: a memory foam or latex comfort layer for body contouring, a micro-coil or transitional foam layer for responsiveness, and a breathable cover for surface comfort. This layered approach provides the plush feel of memory foam with the responsiveness and airflow that prevents the "stuck in the mattress" sensation.
Every time you lie down, your body weight creates pressure between your body and the mattress surface. This pressure isn't distributed evenly—it concentrates at the points where your body protrudes most: shoulders, hips, and to a lesser extent, knees and ankles. In side sleeping, these pressure points bear the full weight of your body on a relatively small surface area.
Research in biomechanics has established that blood capillaries collapse at approximately 32 mmHg of external pressure. When your mattress pushes back with force exceeding this threshold—as happens when bony prominences press against a firm surface—blood flow to the compressed tissue is restricted. Your body's response is neurological: it sends arousal signals that pull you out of deep sleep to change position and restore circulation. This is why you toss and turn on an uncomfortable mattress, even if you don't fully wake up.
Pressure mapping studies consistently demonstrate that soft mattresses reduce peak pressure at shoulders and hips by 40-60% compared to firm surfaces. The comfort layers absorb and distribute the force across a wider area, keeping pressure below the capillary-closing threshold. The result is fewer position changes, longer periods in deep sleep, and significantly less morning pain and stiffness.
Not all "sinking" is equal. Proper contouring means the mattress adapts to your body's curves—filling the gaps at your waist, supporting the natural arch of your spine, and cushioning the protrusions at your shoulders and hips. This is what quality soft mattresses do. Compression, by contrast, is what happens when a mattress simply gives way uniformly under your weight, allowing your entire body to sink without differentiated support. This leads to spinal misalignment and the dreaded "hammock effect."
The key difference lies in the mattress construction. A soft mattress with a quality support core provides contouring at the comfort layer while maintaining structural alignment at the base. The comfort layer handles pressure relief; the support core handles spinal alignment. When both do their jobs, you get the best of both worlds: plush surface comfort with proper underlying support.
For side sleepers specifically, spinal alignment has a different requirement than for back sleepers. Your spine needs to be horizontally straight when viewed from behind—meaning your shoulders and hips must sink enough to bring your spine into a level line. On a mattress that's too firm, your shoulders are pushed upward and your spine curves laterally—a recipe for neck pain, upper back tension, and shoulder impingement.
A properly soft mattress allows your shoulder to sink 3-5cm into the comfort layer, bringing your spine into alignment. Simultaneously, your hip sinks proportionally, preventing lateral spinal curvature. The mattress fills the gap at your waist, providing consistent support along the entire length of your spine. This is why side sleepers consistently report better sleep quality on softer mattresses—it's not just about comfort preference, it's about biomechanical alignment.
Beyond the softness rating, here's what to consider when shopping for a plush mattress in the UK market.
The biggest misconception about soft mattresses is that they lack support. A quality soft mattress has a firm support core (pocket springs or high-density base foam) beneath plush comfort layers. The softness is at the surface where your body contacts the mattress; the support is deeper where your spine alignment is maintained. Never sacrifice support for softness.
Your weight determines how deeply you'll sink. Under 10 stone: a 3-4 firmness works well. Between 10-13 stone: aim for 4-5. Over 13 stone: a soft mattress may cause too much sinkage—consider medium (5) instead. The right softness lets you sink into the comfort layer without reaching the support core beneath.
For soft mattresses specifically, hybrids outperform all-foam designs in two critical areas: temperature regulation and edge support. The pocket coil base provides airflow that counteracts the heat-trapping tendency of plush foam comfort layers, while reinforced edges prevent the "rolling off" sensation common in soft all-foam beds.
The depth of the comfort layer determines how plush the mattress actually feels. Look for at least 7-10cm of comfort material (memory foam, latex, or micro-coils) above the support core for genuine softness. Mattresses with thin comfort layers (under 5cm) marketed as "soft" often feel medium at best.
If you're primarily a side sleeper but occasionally roll onto your back, a medium-soft (4-5) gives more versatility than a true soft (3). Pure side sleepers can go softer; combination sleepers should stay in the medium-soft range to avoid back-sleeping discomfort.
Soft mattresses can feel amazing for the first few nights but reveal issues over weeks—like excessive sinking, heat retention, or difficulty changing positions. Use the full trial period (most UK brands offer 100-200 nights) and pay attention to how you feel after 2-3 weeks, not just the first few days.
Honest answers to the worries most people have about choosing a softer mattress.
Will a soft mattress cause my back to sag?
Only if the mattress is poorly constructed. A quality soft mattress maintains spinal alignment through its support core—the firm base layer beneath the plush comfort layers. Your hips and shoulders sink into the comfort layer (which is desirable for side sleepers), but your spine is held in position by the support system below. The key is ensuring your mattress has a solid support core of pocket springs or high-density foam, not just soft material throughout.
Do soft mattresses wear out faster?
Comfort layers in soft mattresses can develop body impressions sooner than firm models because the softer foams compress more with each use. However, this depends heavily on material quality—high-density memory foam (50+ kg/m³) and natural latex maintain their properties far longer than cheaper low-density foams. A well-made soft mattress with quality materials should last 8-10 years. Rotating your mattress every 3-6 months helps distribute wear evenly.
Won't I sleep hot on a soft mattress?
Soft mattresses do tend to retain more heat because the deeper body conforming increases the contact surface area between your body and the mattress. However, this is manageable with the right construction. Hybrid designs with pocket coil bases provide essential airflow. Gel-infused foams, natural latex, and breathable covers all help counteract heat retention. If you sleep hot and want a soft mattress, prioritise hybrid construction with cooling comfort layers.
Can couples share a soft mattress comfortably?
Yes, and soft mattresses actually offer an advantage for couples: superior motion isolation. The plush comfort layers absorb movement, so you're less likely to be disturbed when your partner moves. However, if one partner is significantly heavier, they'll sink deeper—potentially creating a "roll together" effect. In this case, consider a mattress with zoned support or individual firmness options on each side.
Everything you need to know about choosing a soft mattress.
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