Most people choose a mattress the same way they choose a sofa, they sit on it for a few minutes, decide whether it feels comfortable, and call it done. The problem is that how a mattress feels for three minutes in a showroom is genuinely not the same as how it feels for eight hours every night for the next decade.
Mattress tension is one of the most important decisions you will make for your sleep quality, your spinal health, and how you feel every single morning. And yet it’s also one of the most misunderstood.
Here’s what soft, medium, and firm actually mean, and how to work out which one your body actually needs.
This is the most important distinction in mattress buying, and almost nobody explains it clearly.
Firmness refers to how a mattress feels when you first lie down, that initial surface sensation of soft or hard. Support is something entirely different. Support is about what the mattress does to your spine over the course of a full night’s sleep: whether it keeps your body in neutral alignment, prevents your heavier areas from sinking too deeply, and allows your muscles to fully relax.
A mattress can feel soft and still be genuinely supportive. A mattress can feel firm and provide poor support. The two words are often used interchangeably in the industry, but they have very distinct meanings, and confusing them is one of the most common reasons people end up with the wrong mattress.
“Spinal alignment is the foundation of restorative sleep. When your mattress keeps your spine in a neutral position throughout the night, your muscles can fully relax rather than working to compensate for poor posture. This is why choosing the right tension for your body is not just about comfort. It has genuine implications for how you feel physically each day.”
Dr Katrina O’Donnell
Retired GP, 30+ years NHS experience. Medical reviewer, Land of Beds
The goal of any mattress, regardless of tension, is to keep your spine as close to neutral as possible while you sleep. Too soft and your heavier areas, hips, shoulders, sink too deeply, causing the spine to sag.
Too firm and the mattress resists rather than accommodates your body, creating pressure points at those same areas and forcing the spine to arch. The right tension is the one that sits between these two extremes for your specific body weight, sleep position, and build.
Mattress tension options explained
Here is what each tension level actually means for your body, and who each one is genuinely suited to.
Soft
A deep, cradling feel. The mattress works with your body rather than against it.
A soft mattress provides a plush, sink-in sleeping surface that gently cradles the body, especially at the shoulders and hips. This contouring quality is what makes soft mattresses particularly well-suited to side sleepers. Lying on your side creates pressure at the shoulder and hip, and a softer surface absorbs that pressure rather than concentrating it. For lighter sleepers, a soft tension also ensures the mattress compresses enough to actually support the body, rather than leaving them resting on top of it.
Best for
Side sleepers. Lighter sleepers typically under 11 stone. Those with hip or joint pain who need pressure point relief.
Be aware
Soft mattresses on the wrong spring tension for your body weight can feel like sleeping in a hammock. Heavier sleepers may sink too deeply, losing spinal alignment entirely.
Medium
The Goldilocks tension. Cushioning with noticeable support.
Medium tension mattresses are the most popular choice for good reason. They suit the widest range of sleepers, body types, and sleep positions. They offer enough give to relieve pressure points at the hips and shoulders for side sleepers, while still providing the support needed to maintain spinal alignment for back sleepers. For combination sleepers who move between positions throughout the night, medium tension mattresses are particularly well suited. The responsive nature makes it easier to shift positions without feeling stuck or unsupported.
Best for
Combination sleepers. Average weight sleepers roughly 10 to 16 stone. Couples where both partners have different position preferences.
Be aware
Heavier sleepers over 16 stone may find medium tension compresses too easily under their weight, reducing effective support. A medium firm may be the better choice.
Medium firm
Supportive and stable, with light cushioning on top. The most versatile tension for couples.
Medium firm is where many sleepers find their ideal balance. It offers the structure needed to keep the spine properly aligned, particularly for back sleepers, while still providing enough surface give to cushion the hips and shoulders for those who sleep on their side. It is also the tension most commonly recommended for couples with different preferences, as it balances the support needs of heavier sleepers with the comfort requirements of lighter ones. At Land of Beds, medium firm is consistently one of our most recommended tensions for a wide range of body types and sleep styles.
Best for
Back sleepers. Couples with different sleep preferences. Average to heavier build, roughly 11 to 18 stone. Those with mild lower back discomfort.
Be aware
Lighter sleepers who sleep predominantly on their side may find medium firm creates too much pressure at the shoulder. A medium tension may be more comfortable.
Firm
Very supportive with minimal surface give. The spine stays straight.
Firm mattresses provide a robust, supportive sleeping surface with very little sink. For back and front sleepers, positions that naturally require more support to maintain proper spinal alignment, a firm tension keeps the body lifted and the spine straight throughout the night. For heavier sleepers, a firmer tension prevents excessive compression that can compromise alignment on softer mattresses. Firm mattresses also tend to offer more consistent support over time, as denser materials resist sagging and deterioration more effectively.
Best for
Back and front sleepers. Heavier sleepers over 16 stone. Those who prefer a flatter, more stable sleeping surface. People with chronic lower back discomfort.
Be aware
Lighter sleepers and side sleepers often find firm mattresses create uncomfortable pressure at the shoulders and hips, as the surface does not compress enough to absorb that load.
Extra firm / orthopaedic
Maximum support. The spine is held in a natural position with no compromise.
Extra firm and orthopaedic mattresses provide the highest level of support available and are designed to keep the spine in a healthy, natural position with minimal surface give. They distribute body weight evenly across the sleeping surface, reducing concentrated pressure on any one area. They are most commonly recommended for heavier sleepers, those with chronic back or neck discomfort, and people who sleep on their back or front and need a flatter surface to prevent the lower back from arching.
Best for
Heavier sleepers. Those with chronic back or neck discomfort. Front sleepers needing a flat, stable surface. Anyone advised by a healthcare professional.
Be aware
Extra firm is not suitable for all types of back discomfort. If your condition requires cushioning rather than support, this tension may worsen symptoms. Always consult a healthcare professional if unsure.
How your body weight changes everything
This is the factor most mattress guides underplay, and it’s one of the most important variables in the whole decision.
The same mattress will feel and perform very differently depending on the weight of the person sleeping on it. A medium tension mattress that provides perfect support for a 12-stone sleeper may feel too firm for an 8-stone sleeper, who won’t compress it enough to benefit from its support layers, and too soft for a 17-stone sleeper, who may sink through the comfort layers entirely and lose spinal alignment.
At Land of Beds, we always recommend thinking about body weight alongside sleeping position when choosing tension. The two variables work together, and neither is sufficient on its own.
Body weight
Recommended tension
Why
Under 10 stone
Soft to medium
Lighter sleepers need a mattress that compresses enough to support the body and relieve pressure at the hips and shoulders.
10 to 13 stone
Medium
The most versatile range. Medium tension provides the right balance of cushioning and support for average weight sleepers.
13 to 16 stone
Medium to medium firm
As weight increases, the comfort layers compress more easily. A slightly firmer tension ensures the support layers engage properly.
16 to 18 stone
Medium firm to firm
Heavier sleepers need more resistance to prevent excessive sinkage at the hips, which can compromise spinal alignment.
Over 18 stone
Firm to extra firm
Extra firm or orthopaedic mattresses help distribute body weight evenly and maintain support under higher loads.
“Don’t underestimate the importance of your sleeping position. Side sleepers usually do better with the contouring of memory foam or a softer spring tension to relieve pressure on the hips, while back sleepers often benefit from the sturdier support of an orthopaedic or firmer pocket sprung mattress.”
Charlotte
Bed and mattress expert, Land of Beds
Tension by sleeping position
Your sleeping position determines which parts of your body bear the most pressure overnight, and that directly changes what tension you need.
Side sleepers
Sleeping on your side creates concentrated pressure at the shoulder and hip. A softer to medium tension allows those areas to sink into the comfort layer, keeping the spine level rather than forcing it to bend. Side sleepers who use a mattress that is too firm often wake with numb arms, shoulder discomfort, or hip pain. These are clear signs the mattress is resisting rather than accommodating the body.
Sleeping on your back supports healthy spinal alignment, but only if the mattress provides the right balance of support and comfort. If it is too soft, the lower back can sink and create strain. If it is too firm, pressure builds at the shoulders and tailbone. A medium firm to firm tension helps maintain the natural curve of the spine while still allowing enough give to prevent pressure build-up.
Front sleeping places strain on the lower back and neck because the natural curve of the spine is reversed. A firmer mattress helps keep the hips elevated and prevents the lower back from arching excessively. Softer mattresses allow the hips to sink below the chest, increasing spinal strain and discomfort.
If you move between positions throughout the night or cannot predict where you will settle, a medium tension is usually the safest starting point. It provides enough give for side sleeping and enough support for back sleeping without strongly favouring either.
Your body will tell you if the tension is wrong, most people just don’t know how to interpret what it’s saying.
Signs your mattress may be too soft
You wake with lower back discomfort that eases within 15 to 20 minutes of moving around. Your hips feel like they have sunk overnight. You feel unsupported or like you are sleeping in a hollow. Your spine feels stiff rather than rested. You find yourself rolling toward the centre of the bed without intending to.
Signs your mattress may be too firm
You wake with shoulder or hip discomfort even though you have not injured either. Your arms go numb during the night, particularly if you sleep on your side. You feel pressure at contact points such as shoulders, hips, and heels rather than support across the whole body. You find yourself waking frequently to change position.
A note on the break-in period
A new mattress often feels different at home compared to how it felt in a showroom, and it can feel different again after a few weeks of regular use. Allow at least eight to twelve weeks before deciding whether a tension is right for you. During this time, rotate the mattress regularly to help the fillings settle evenly. If discomfort continues beyond this period, it is more likely to be a tension issue rather than a break-in phase.
Couples with different tension preferences
One of the most common challenges in mattress buying, and one of the most solvable.
If you and your partner have different tension requirements, different body weights, different sleeping positions, or different physical needs, there are practical solutions that don’t require one of you to compromise.
Medium firm as compromise
For many couples, a medium firm mattress is the most effective compromise. It balances support for heavier sleepers with comfort for lighter partners and suits a wider range of sleeping positions than either extreme. If both of you are broadly average weight and neither has specific physical requirements, this is almost always the best place to start.
Dual tension mattresses
Some mattresses are made with different spring tensions on each side of the bed, typically one softer and one firmer. These are designed for couples with significantly different tension requirements and are worth considering if the difference between your needs is substantial.
Zip and link
Two single mattresses zipped together to form a super king is one of the most practical solutions available. Each partner sleeps on a completely different mattress with their own preferred tension, with no compromise required. It is also the only option that allows each side to be replaced independently over time.
Mattress toppers
If your mattress is too firm for one partner, a mattress topper on their side can soften the surface feel without compromising the underlying support. This is a practical and relatively affordable adjustment that can extend the life of a mattress that works well for one partner but not quite for the other.
Frequently asked questions
Is firm better for back pain?
Not necessarily, and this is one of the most persistent myths in the industry. The right tension for back pain depends on what is causing the pain, your body weight, and your sleeping position. A mattress that is too firm can create or worsen pain by putting pressure on the shoulders and hips. The goal is neutral spinal alignment, and the tension that achieves that will vary from person to person. If you have chronic back issues, it is worth consulting a healthcare professional before making a decision.
Can I change the tension of my mattress?
You can soften the feel of a firm mattress with a mattress topper, but you cannot significantly increase the firmness of a soft mattress. If your mattress feels too soft, a topper is unlikely to solve the problem and you may need to consider a replacement. If it feels too firm, a good quality memory foam or latex topper can make a noticeable difference to comfort at the surface.
Does tension affect how hot I sleep?
Yes, softer mattresses, particularly those with thicker foam comfort layers, tend to contour more closely to the body and can retain more heat as a result. If you are a warm sleeper and prefer a softer feel, look for mattresses with gel infused foam, latex layers, or breathable natural fillings such as wool or cotton, which regulate temperature more effectively.
How long does a mattress last?
A quality mattress, properly cared for, will typically last seven to ten years. Longevity depends on the materials used, how regularly it is rotated, and whether the tension was well matched to your body weight. A mattress used outside its intended weight range will wear out more quickly, which is another reason why choosing the right tension matters beyond immediate comfort.
Still not sure which tension is right for you?
Tension is personal, and no guide, however thorough, can replace the experience of actually lying on a mattress with the right support for your body.
At Land of Beds, our team of sleep experts provide independent, free advice based on your specific needs, sleeping position, and build.
We stock a full range of tensions across memory foam, pocket sprung, latex, hybrid, and orthopaedic mattresses, and we’ll help you find the right one without the pressure.
You can also visit us in our showrooms in Greater Manchester and Cheshire, where we’d encourage you to spend proper time on any mattress you’re seriously considering. Not three minutes. Proper time.
Browse by tension
Shop the full range filtered by soft, medium, medium firm, firm and extra firm.
Dr O’Donnell is a retired General Health Practitioner with over 30 years of experience in the NHS. Her extensive background in patient care, health education, and preventative medicine brings trusted medical insight to the content we share. Dr O’Donnell has reviewed and approved this blog to ensure the information supports our commitment to promoting healthier sleep and wellbeing.
Written by Alice Littler
Alice brings a background in marketing, design, and branding to Land of Beds, where she focuses on making sleep advice simple, relatable, and practical for everyday life. She holds a degree in Graphic Design with a specialism in branding and design, giving her a strong understanding of how interior spaces, colour, layout, and environment can influence comfort, mood, and overall wellbeing.
Her creative background allows her to provide both expert bed and mattress guidance and bedroom design inspiration that helps customers create spaces that feel as good as they look.
Alongside her work in marketing and branding, Alice has collaborated with internationally recognised brands including Campari and Aperol, Paulaner, and Malfy, helping develop her expertise in consumer-focused communication and lifestyle content. She has also been trained by and works closely with leading UK bed and mattress manufacturers including Harrison Spinks, Hypnos, and Vispring, building extensive knowledge of mattress technology, sleep ergonomics, bedroom comfort, and sleep wellness.
Passionate about the life-changing impact of quality sleep, Alice creates content designed to help readers make informed decisions to improve their sleep environment, wellbeing, and everyday routine.
