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Firm or soft mattress - which one should You choose?

25 czerwca 2025
firm or soft mattress, types of mattress firmness, mattresses
Choosing the right mattress for sleeping is one of the most important decisions regarding our daily comfort and health. However, the purchase decision is often based on misconceptions, such as the belief that heavier individuals should sleep on firm mattresses, while lighter individuals should choose very soft ones. In fact, knowledge from biomechanics and sleep physiology shows that what truly matters is matching mattress firmness to the physiological body alignment, not body weight.

In recent years, public awareness of sleep ergonomics has grown significantly. Consumers have come to deeply appreciate the importance of regeneration and deep sleep, as well as the mattress's impact on everyday functioning. More and more people realize that good sleep is not just about comfort, but also a long-term investment in spinal health. This affects metabolism, mood, and cognitive abilities—in essence, overall quality of life.
Let’s remember that contrary to a common myth, mattress firmness should not be selected based on a person’s weight. The human body distributes proportionally on a mattress, so someone with a higher body mass also has a larger surface area. That means they have more contact points compared to someone lighter. As a result, pressure on a single point is not necessarily greater than in a lighter person.

A mattress that is too firm does not allow for contouring immersion of the body, which leads to pressure in the hip and shoulder areas. This results in muscle tension that should be avoided. On the other hand, a mattress that is too soft can cause sinking, leading to unnatural spine curvature. Proper mattress dynamics help maintain the natural spinal curves and evenly distribute body weight.

That’s why a well-designed medium-firm mattress, which provides stable support while allowing for gentle contouring of key areas like shoulders and hips, is the most functional solution currently available. This is confirmed by research in ergonomics and physiotherapy, which shows a correlation between comfort and medium firmness.

The shamelessly perfect Osaka Air mattress is built around this very idea. It combines high-resilience HR foams with a layer of memory foam, ensuring the right balance between comfort and support, without the sinking effect. This approach is based solely on human physiology, not on harmful stereotypes.
For many years, a firm mattress was seen as a symbol of healthy sleep, especially in marketing messages. Today, however, we know that a firm mattress is not necessarily good for the spine. Firm mattresses can impair blood circulation and cause discomfort, particularly in the joints and muscles. Their users may wake up feeling stiff or sore—a sign that the body wasn’t able to relax.

On the other hand, very soft mattresses also fail to provide proper spinal support, especially in the lumbar region, which is often neglected. This can lead to sinking and excessive bending, resulting in back pain over time and reduced regeneration quality—as well as frequent position changes at night that interrupt deep sleep cycles.

The key is matching flexibility to the body’s natural needs. Open-cell foams, like those used in ONSEN® mattresses, intelligently adapt to the user’s anatomy. They also enhance air circulation, reducing overheating and sweating—common problems with poorly designed mattresses.

When it comes to mattresses, extreme softness and excessive firmness are two harmful extremes. They are a misguided response to the needs of sleep. Only by choosing a well-designed medium-firm mattress are you making a decision based on scientific knowledge.
A medium-firm mattress meets the diverse needs of various body types and sleeping positions. Properly selected high-resilience foams, such as HR30100 and HR35120 in the Osaka Air mattress, offer durability, responsiveness, and resistance to deformation—all key qualities. The V50075 memory foam in the second layer provides anatomical support, as its placement eliminates the sinking effect.

According to scientific research, properly chosen mattresses improve sleep quality—particularly for people with back or shoulder pain, as well as those with sleep disorders. Medium firmness is considered the most comfortable by most people—regardless of body weight, since weight isn’t a relevant factor.

Choosing the right bedroom mattress is not about a subjective feeling of comfort during a store visit. In the 21st century, there’s no place for buying mattresses in brick-and-mortar stores where proper testing isn’t possible—not to mention the return process, which is usually not an option there. It’s a strategic decision that affects health and quality of recovery, and by extension, your everyday well-being. That’s why it’s wise to trust the logic of proportional body distribution, not outdated myths.

ONSEN® not only understands this—it educates its tribe to understand it too. Medium firmness isn’t a compromise; it’s a functional optimum—a solution derived from knowledge.

Rozsądek i wiedza ponad mity

Choosing a mattress is not a matter of personal whim, but of health. A medium-firm mattress like the Osaka Air mattress from ONSEN® is the most well-founded choice for a wide range of users, regardless of body type. It supports proper spinal alignment, ensures thermal comfort, aids regeneration, and reduces pressure points.

The myths claiming that a heavier person should sleep on a board-hard mattress, and a lighter person on one as soft as cotton, have no scientific basis. What matters more is body structure—its surface area and how weight is distributed. That’s why it’s worth trusting science over stereotypes. Only then can we build healthy, restorative sleep and challenge the status quo together.

We also encourage you to explore other articles on the best sleep and health blog, as well as the Encyclopedia of Healthy Sleep prepared by the ONSEN® team of specialists. For those who care about spine health, we recommend a set of spine exercises prepared by our physiotherapist.

FAQ: Firm or soft mattress?

Is a soft or firm mattress better?

Neither extremely soft nor very firm mattresses are ideal. A good mattress conforms to the body without a sinking effect while providing stable support for the spine. Too soft, and the body sinks without support; too firm, and pressure and muscle tension occur. A medium-firm mattress offers the best balance of comfort and ergonomics. The soft vs. firm divide is too simplistic - quality, elasticity, and body alignment matter more.

Is it better to sleep on a firm or soft mattress?

Neither extreme is good. A mattress that?s too firm prevents proper body contouring, leading to pressure on hips and shoulders. A mattress that?s too soft lets the body sag and curves the spine unnaturally. A well-designed medium-firm mattress is the best solution?it supports and adapts to the body?s anatomy.

Do doctors still recommend firm mattresses?

No. That?s an outdated belief. In the past, it was thought that a rigid body position was always beneficial. Today, we know that such stiffness can do more harm than good. Similarly, many fractures are no longer routinely immobilized with a cast. Firm mattresses are an old-fashioned choice that?s falling out of favor.

Why do firm or soft mattresses cause back pain?

A too-firm mattress applies pressure to sensitive points, disrupting circulation and causing muscle tension?leading to stiffness and pain in the morning. A too-soft mattress fails to support the spine, letting the lumbar area sag, which over time causes discomfort and sleep disruption.

Why do I have a stiff back even though I sleep on a firm mattress?

Firm mattresses prevent the body from contouring naturally. Without proper relief for hips and shoulders, pressure builds up and causes stiffness and pain. Such mattresses interfere with muscle relaxation and blood flow, leading to stiffness after sleep.

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