There’s nothing quite like sinking into a comfortable bed. While the perfect pillows, a thick duvet and soft sheets are important, what’s most paramount is finding the best mattress for you.

Bed-in-a-box designs are nothing particularly new, with the likes of Simba, Emma and Eve all launching their own options. But if there’s one brand to know, it’s Ergoflex as it’s been unfurling comfortable mattresses from boxes for more than a decade.

Billed as the “original bed-in-a-box” company, the brand was first launched as a more affordable option to Tempur mattresses, using density memory foam in all of its products to offer the same supportive contouring to the body as you sleep. And the company is so confident in its innovation that it operates on a “one perfect mattress” philosophy, meaning that the 5G is the only model it currently sells, as it can suit every type of sleeper.

The Ergoflex 5G mattress typically costs £966 for a double, but thanks to its current offer, you can save 50 per cent by using the code SPRING50, bringing the price right down to just £483. To help you decide whether this OG bed-in-a-box is going to give you a comfortable night’s sleep, we put the Ergoflex 5G mattress to the test.

How we tested

To get a feel for its purported charms, we spent several weeks sleeping on the Ergoflex 5G mattress, with two people on the standard double. During the review process, we took note of first impressions and aesthetics, how long it took to recover once released from its cardboard chamber and assessed comfort and support with each passing night.

Ergoflex 5G mattress

Best: Bed-in-a-box brand

Sizes available: Single, double, euro double, king, euro king, super king

Mattress depth: 23cm

Material: Memory foam

Feel: Firm

Trial period: 30 days

Warranty: 10 years

Design and features

When we first opened our Ergoflex mattress, it instantly uncurled and began “inflating”, which, impressively, only took about two hours, although the brand recommends leaving it four. There was a very slight smell, which is fairly typical in mattresses of this nature, but this had dissipated by the time we got ready to sleep on it that evening.

It’s important to ensure that you have your 5G the right way up from the get-go, as it isn’t designed to be flipped, only rotated every three months. It comes with a protective cover that you can unzip and machine wash regularly, so you need to have it zip side down to ensure all of the layers are the right way up to offer their benefits effectively.

Speaking of layers, for those who like the technical breakdown, strap in: the 5G is a five-layer model comprising of this outer cover, another protective inner cover, and then 9cm of visco-elastic memory foam, which allows you to sink in but still feel supported.

This is followed by a signature 5cm cool-sleep airflow layer, which allows air to circulate in order to keep your temperature throughout the night – we remained cool throughout the night despite testing in throughout muggy August, so can attest to its effectiveness here.

And last but not least, there’s a further 8cm of high-resilience foam at the base to reinforce that solidity. We’d say the 5G certainly falls at the firmer end of the mattress spectrum, but it doesn’t feel hard or excessively dense.

Choosing the right size can be a little confusing, as the euro options are ever so slightly larger, but most UK bed frames will conform to the usual single, double or king sizing. We’d recommend that you measure your bed to ensure the correct option is selected. At first glance, the 23cm depth looked a little small to us, but this is because Ergoflex eschews the popular “hybrid” model of memory foam and springs combined – as it’s only foam at work here, the 5G is a little shallower than some competitors, but this is not to its detriment in terms of comfort (more on this below).

Overall it looks good, with a subtle white and grey design that doesn’t peek through even a fairly flimsy white sheet, and feels even better. We’ve slept on softer sprung mattresses in the past, and so we did go through a short adjustment period, but once we’d snuggled in for a few consecutive nights we were swiftly converted, and can’t see ourselves going back.

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Comfort and performance

Ergoflex notes that the structure of its memory foam interior is specifically designed to relieve pressure, and this was demonstrable almost immediately – every area of the body remains evenly weighted and propped up, even while lying in awkward positions. We felt it was especially good for the back pain that had been plaguing us for weeks prior – while it’s not entirely healed, there’s been noticeable relief since we moved the 5G into our bedroom and found that it improved our spinal alignment during slumber.

This model is also great if you sleep with a fidgety partner – we weren’t woken up by any movements our fellow tester made during the night, and vice versa (a major plus in our household!)

One slight downside is that there is only one firmness option available, so if you try the 5G and find that it isn’t for you, there isn’t the choice to switch to a different line. The fact that the one model available is already exceedingly comfortable means that we feel this is highly unlikely, but it’s worth noting all the same, as this is something that some other bed-in-a-box brands do offer. However, there is a 30-day trial period, so you have a month to make up your mind either way.

Another factor to be aware of is that Ergoflex warns against using the 5G on slatted bases where the slats sit more than 2.5 inches apart, as this can impact its performance. Most standard beds should cater to this no problem, but get your tape measure out to check yours before ordering just in case.

If this sounds like the mattress for you, don’t forget to use the code SPRING50 at checkout to benefit from the 50 per cent saving.

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The verdict: Ergoflex 5G mattress

While it takes a little time to adapt to a mattress this firm if you’re not used to it, the Ergoflex 5G mattress really does allow for a deep, comfortable, undisturbed night’s sleep.

Although we haven’t yet had the pleasure of testing the 5G over a number of years, several reviewers on the company’s Trustpilot page say they’ve happily slept on theirs for over a decade – so if you do choose to buy one, it would appear that that 10-year warranty holds up through prolonged use, too.