Is it good to sleep on a soft mattress?

Woman asleep on her side
(Image credit: Getty)

Mattresses come in a range of firmness levels: through soft, medium-soft and medium, to medium-firm and firm. While maximum cushioning sounds like it should equal a great night's sleep, is it actually good to sleep on a soft mattress? The simple answer is: it depends. 

By far the biggest factor in terms of what firmness of mattress will suit you will be the type of mattress you've used throughout your life. In other words, if you normally sleep on a medium or firm mattress, and you generally wake up feeling refreshed and rested, it's probably best to stick with what you know. 

However, if you have a medium or firm mattress and hate it, it could be worth trying a soft or medium-soft one. Be aware, though, that while this style suits many, it's unsuitable for others. So in this article, we'll explain what the main differences are, to give you an idea of which group you fit into. 

If you're still uncertain, bear in mind that the best mattresses tend to come with generous free trial periods. That means you can try a soft mattress, and simply return it if it doesn't work for you. Some models are even available in a range of firmness options (that's the case with our #1 US pick, the Saatva Classic and the Brook + Wilde Lux in the UK). Alternatively, you could try softening up your existing mattress by adding a soft mattress topper (if you need one of those, see our guide to the best mattress toppers).

Is a soft mattress a good choice?

The short version is: a softer mattress might be good for lighter people, side sleepers, people with joint pain or potentially anyone who shares a bed with a restless partner. A soft mattress might not such a good choice for people who suffer from back pain or mobility issues, larger or heavier people, back or front sleepers, or those who tend to sleep hot. These are guidelines only though, and personal preference will come into it too.

Let's take a closer look at those categories, and the reasoning behind them. 

Yes, if you like to 'sink in' to a mattress

We'll start with the obvious point: a soft mattress makes you feel like you're sinking into the bed. Whether this is a good or bad thing is ultimately a matter of personal taste. Some people love the feeling. Others hate it and instinctively prefer a firmer mattress, where you're more 'on top' than 'in' the bed. 

Context is also important. For example, you may have stayed in a hotel with a particularly soft mattress, and found it delightful. But it's worth asking yourself: how much was that down to the mattress? And how much was the experience of being on holiday with loved ones, away from all your cares and worries, and perhaps a few glasses of wine too?

Yes, if you suffer joint pain

Two delivery men placing the Saatva classic mattress down on a bed frame

The Saatva Classic is available in a range of firmness options (Image credit: Saatva)

Because a soft mattress lets you sink in, it reduces pressure on your shoulders and hips, compared with a firmer mattress. This is why soft mattresses feel more comfortable for many people, and can help with joint and hip pain. 

It can be a double-edged sword, though, because a soft mattress will generally supply less support than a firm one. Depending on how much you weigh and how you sleep, that can mean your back dips down too much while you sleep, which can cause spinal problems.

So what's the best balance between pressure relief and support: soft, medium or firm? Sadly, there's no easy answer to this, because everyone's body and sleep style is different. So it's very much a case of finding the right type of mattress for you, based on trial and error, and for most people that will be somewhere in between soft and firm. 

Probably not, if you suffer back pain

What if you suffer from back pain? While everyone's body is different and it's difficult to generalize in this thorny area, a rule of thumb is that the best mattresses for back pain are on the firmer side. According to sleep specialist, coach and speaker Angela Holliday-Bell (opens in new tab): "In general, back pain sufferers tend to do better with medium-firm mattresses that provide enough spinal support to alleviate pain."

And this view isn't just based on anecdotal experience: there's scientific research to back it up. Angela references a study from The National Library of Medicine (opens in new tab), published in 2015. "This was a systematic review that included 24 clinical trials that assessed the relationship between mattress design and sleep quality and found that mattresses that were subjectively medium-firm were optimal for promoting sleep quality and spinal alignment," she summarizes.

Yes, if you're a side sleeper; no if you're a back or front sleeper

If you sleep on your side, a soft mattress will do a better job of cushioning your shoulders and hips. In contrast, a firmer one may exert too much pressure, creating discomfort and preventing you from getting a good night's sleep. To choose the best one for you, check out our guide to the best mattress for side sleepers

Conversely, if you sleep on your back or your front, you may find your hips and pelvis sink in to a soft mattress too much, leading to discomfort and poor spinal alignment over time. For this reason, back or front sleepers are generally better off with a firmer mattress. 

Woman lying on her side on the Helix Midnight mattress

A softer mattress, like the Helix Midnight, lets the hips and shoulders sink in (Image credit: Helix)

Yes, if you're a lightweight person

If you weigh less than the average person, you'll find a firmer mattress particularly problematic in terms of pressure relief. In contrast, you may find that only a softer mattress provides enough 'give' on your shoulder and hips to get truly comfortable. Conversely if you're heavier than average, you'll probably need more support than a soft mattress can provide. Generally, heavier people require a firm mattress with a good depth. 

No, if you have mobility issues

If you have problems moving about due to disability, injury or other health problems, a soft mattress isn't the best bet. Changing positions and getting in and out of bed is normally be easier and less painful with a firm mattress.

Perhaps not, if you sleep hot

If you live in a hot climate, then the fact you sink into a soft mattress can make it more difficult to stay cool at night, because less of your body is exposed to the air. That said, this is only one (relatively minor) factor among many. In fact, we'd suggest that if you have a particular issue with sleeping hot, your first port of call should be to invest in one of the best cooling mattresses, which use a range of specialty materials to help regulate in-bed temperature and wick away body heat (they're more of a thing in the US than the UK).

A woman with dark curly hair sits on the Cocoon by Sealy Chill

The Cocoon by Sealy Chill mattress is designed specifically to prevent overheating (Image credit: Cocoon by Sealy)

Yes (probably), if you sleep with a partner

What mattress companies call motion transfer is the degree to which movement is shared from one part of the mattress to another. Softer mattress tend to have problems with motion transfer, which means that if you're a fidgety sleeper, your partner's sleep can be disrupted, and vice-versa. With a firm mattress, especially one featuring memory foam, there's generally less motion transfer. 

That said, it's not the only factor here, and many mattresses of all firmness levels use clever design and special materials to reduce motion transfer. Another issue is that you may prefer a different level of firmness to your partner. One design that gets around that is the Dormeo S Plus Evolution (opens in new tab), which is divided into two halves, each of which can be flipped to a softer or firmer surface.

Tom regularly writes about sleep for Tom's Guide and our sister site T3.com. Over the years he's tested a number of mattresses, duvets and pillows, and as a back pain sufferer, has a keen interest in finding ones that offer maximum support. Plus, in running a successful Airbnb business, sleep hygiene and providing the right bedding for guests has become a big part of his day-to-day life.