I thought this cheap firm mattress would never suit side sleepers but after a week of retesting, I’ve been forced to eat my words

On the left, a close up of mattress tester Nicola Appleton lying on her side on the Siena Signature Mattress in our sleep studio, with a laser line indicating the straightness of her spine. On the right, the Siena Signature Mattress in the bedroom of our sleep writer Ruth Jones.
(Image credit: Future)

For the past six months I've been testing the Siena Signature and I've long rated it among the best mattresses you can buy, particularly with a queen just $294 at Siena. However, there was always a caveat: due to the firm feel, I struggled to recommend the mattress to side sleepers.

Last week changed all that, when circumstances forced me to sleep on my side and I discovered 'hey, this is actually pretty comfortable — you just need a little patience.'

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Key take-aways:

  • The Siena Signature mattress is firm and doesn't have much sink — two features that tend to be bad news for side sleepers.
  • But given a little time, the foams do slowly respond to cradle the body and reduce pressure build-up.
  • Plus, the excellent support means your spine is held straight and you can avoid hip sink.
  • So, if you're a side sleeper who prefers a firm mattress, it's a good pick.
  • However, lightweight side sleepers should look for a softer bed, like the Helix Midnight Luxe or Nectar Premier Memory Foam.
Siena Signature (twin)
Siena Signature (twin): $159 at Siena

The best cheap mattress we've tested, the Siena Signature excels when it comes to support and motion isolation, punching well above its price tag of just $294 for a queen. It also comes with a 10-year warranty and a 180-night trial — so side sleepers, you can put my claims to the test at home.

Our Siena Signature mattress review: ★★★★
User score: ★★★★½

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Why the Siena Signature is a firm mattress for side sleepers

Let's give some context. I started head-to-toe testing for my Siena Signature mattress review roughly six months ago and I've been sleeping on it at home ever since.

Both myself and my fellow testers had the same opinion when side sleeping on the Siena: comfortable for short bursts but likely to result in a sore arm overnight. As a stomach sleeper, this was no big deal and I happily declared the Siena one of the best mattresses for stomach sleepers. It's kept me comfortably supported ever since.

The Siena Memory Foam Mattress placed on a white bed frame in our blue testing bedroom

(Image credit: Future)

But I've recently been plagued by a persistent cough that got worse when I was lying on my front. It was impossible to sleep when every few minutes I had to (ineffectually) clear my throat.

So I braced myself for a trade-off — one sore arm in exchange for no more coughing — and committed to sleeping on my side.

The pressure relief isn't immediate — but it is there

The best mattresses for side sleepers tend to have a lot of cushioning, to take pressure off the 'touch points' aka the parts of the body that press heaviest into the mattress (that's your shoulder and hips.)

This is something the Siena lacks. During our mattress testing we use a 25kg weight to measure sinkage and pressure relief. On the Siena, it sank just 2.5 inches at the shoulder area — a full inch less than the equivalent area on the rest of our top five mattresses.

A close up of a 25kg weight balanced on the Siena Memory Foam Mattress in our sleep studio. There's a tape measure attached to the side of the weight and a laser line is hitting the tape measure at roughly 3.5 inches, indicating how far the weight has sank into the mattress. To the right, a phone displaying a stopwatch at 30 seconds; how long the weight has been on the Siena Mattress.

Imagine the weight is your hip (Image credit: Future)

What this means is that instead of pressure relief, you would expect to experience pressure build-up at the touch points, resulting in soreness.

However, the Siena does have cushioning. You just have to give it some time.

The top comfort layer of the Siena is made of memory foam, a material that famously responds to warmth and pressure. This memory foam takes a little longer to react than most (and at just two inches thick, it's never going to have the deep sink of a taller bed like the Nectar Premier Memory Foam.)

But as the bed warmed the Siena began to gently cradle my body, taking the weight off my shoulders and hips. No sore arms and no cough — I was asleep in minutes.

Support means no hip sink and straight spines

Side sleeper mattresses sometimes exchange support for softness, causing your entire body to sink into the bed like you're being sucked into quicksand.

This might feel cozy initially but during the night a lack of support is likely to lead to an ache at the back, hips and even the shoulders (it's a problem I experienced on the softer Zinus Green Tea Memory Foam Mattress.)

A close up of a hand pushing into the surface of the Siena Memory Foam mattress. The hand is pressing hard to try and making an indentation but it still barely sinks into the mattress.

(Image credit: Future)

However, the Siena mattress knocks it out of the park when it comes to support. Beneath the comfort layer that delivers the aforementioned relief is a strong foam support core which keeps the body lifted from head-to-toe.

It's this feature that makes the Siena a winner for back and stomach sleepers — but it also benefits side sleeping.

For me, the biggest upside was a lack of hip sink. On softer beds I tend to find my hips drift well below my shoulders, which causes pain at my lower back. On the Siena, I was supported from the neck down.

If you're a side sleeper who prefers the even support of a firm bed, the Siena will deliver the feel you need (without sacrificing your shoulders.)

But it won't suit all side sleepers

I was surprised by how comfortable I found the Siena for side sleeping because it lacks many of the features you expect from this type of bed: a plush top, a medium-firm finish, ample cushioning.

But while not a major drawback for me, it's likely to be a different story for other side sleepers. Primarily, those with a lighter build.

Two of our mattress testers sit on the Siena Signature Mattress on a bed frame in our testing studio. On the left, Nicola Appleton sits close to the side of the mattress to test the edge support. On the right, Frances Daniels sits on the sleeping area of the bed to better understand the comfort.

(Image credit: Future)

Mattress firmness is subjective and as a general rule a mattress will be perceived as firmer by those with a lighter frame and softer by those with a heavier frame.

So lightweight side sleepers typically need a bed with plenty of cushioning to keep the shoulders and hips from growing numb. The Siena is unlikely to deliver.

And this is backed up by our Sleep Lab testing; of everyone who tried the Siena Mattress, slight side sleeper Frances Daniels found it the least comfortable.

Side sleeper mattress alternatives to shop now

If you're looking for a mattress that delivers a more traditional side sleeper experience (cushioned plushness, essentially), then you might want to skip the Siena.

There are plenty of mattresses on the market that should suit your needs so I've rounded up my three favorites below..

When choosing any mattress, my top tip is to opt for one with a sleep trial. This is an at-home testing period that allows you to break the bed in and see if it works for you.

With a trial, you don't have to take my word for it — you can see for yourself if the mattress suits your needs and if it doesn't, you can return it for a refund (some mattress brands charge a processing fee.)

Helix Midnight Luxe (twin)
Helix Midnight Luxe (twin): was $1,436.25 now $1,149 at Helix Sleep

One of the best hybrid mattresses we've tested, the Helix Midnight Luxe is our favorite bed for side sleepers — the Euro top and enhanced coil base deliver an exemplary blend of pressure relief and support. It's softer then the Siena, as we discovered in our Helix Midnight Luxe mattress review, but the medium feel should suit many back sleepers as well. A queen is currently $1,919 (down from $2,398) but keep an eye out for the next Helix mattress sale where you might score a 25% discount.

Our Helix Midnight Luxe mattress review: ★★★★½
User score: ★★★★½ (8,300+ reviews)

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Zinus Green Tea Memory Foam (twin)
Zinus Green Tea Memory Foam (twin): at Amazon

The Zinus earned a place among our top-rated memory foam mattresses thanks to its plush, slow-moving foams that make it a dream for side sleepers. While our Zinus Green Tea mattress review team found it could sleep hot and the edge support was poor, at just $219.99 for a queen on Amazon (was $233.99), it's exceptional value for money.

Our Zinus Green Tea Memory Foam mattress review: ★★★½
User score: ★★★★ (167,000+ reviews)

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Nectar Premier Memory Foam (twin)
Nectar Premier Memory Foam (twin): $549 at Nectar Sleep

The Nectar Premier delivers a traditional memory foam feel. It's plush, slow-moving, and eases around your body to cradle the hips and shoulders. It was a hit with the side sleepers during our Nectar Premier Memory Foam mattress review, and the motion isolation is excellent for couples. Nectar mattress sales remain steady with a queen typically $949, and it comes with a 365-night trial.

Our Nectar Premier Memory Foam Mattress review: ★★★½
User score: ★★★★½

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Ruth Jones
Senior Sleep staff Writer

Ruth is an experienced Senior Staff writer at Tom’s Guide, covering all things sleep and mattresses. She writes to help people sleep better, from how-tos to the latest deals to mattress reviews, and has interviewed an array of experts who share her passion. She is also our specialist on memory foam — she’s flown around the world to see memory foam being made — and leads our hotel mattress content. She has a deep interest in the link between sleep and health, and has tried enough mattresses, from Helix to Nectar to Simba, to know the right bed really can make a difference to your wellbeing. Before joining the team at Tom’s Guide, Ruth worked as a sleep and mattress writer for our sister website, TechRadar.

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