Tweak Slumber Nrem mattress review

This unique customisable mattress aims to help back and neck pain – and means you'll never have to compromise with your partner on the firmness of your mattress again.

Tweak Nrem mattress review

T3 Verdict

The Tweak Slumber Nrem mattress is flexible, comfortable and phenomenally supportive: our sleep improved immediately. The customisable design really works, making it a good choice for anyone with back or neck pain – and we love that you can choose a different firmness setup to your partner. Co-sleeping and back ache have never had it so good.

Reasons to buy

  • +

    You can tailor the firmness

  • +

    Reactive foam is very comfortable

  • +

    Supportive in the right places

  • +

    Minimal movement transference

Reasons to avoid

  • -

    Some might find it a little warm

  • -

    May have to experiment to find the right setup

The Tweak Slumber Nrem is a hybrid mattress with a unique USP: it’s customisable, letting you tailor the firmness levels in different areas to your own preference. Designed specifically for people with chronic pain, the mattress is divided into five zones – each with an interchangeable foam insert ranging between soft, medium and firm – that you can rearrange whenever you like to create a bespoke sleeping experience. 

But that’s not all: because the Nrem mattress is also split in half down the middle (for double sizes and larger), you don’t have to compromise with your partner on the firmness of your mattress. You have five foam inserts each and can set up your side of the mattress as you see fit. That, in itself, makes the Nrem worthy of submission to our best mattress guide.

Suffer from upper back pain? Try a firm insert under that section of your body. Does your partner prefer a softer mattress? Or need more comfort for an area of acute pain? They can cushion it with a soft insert exactly where they need it. 

It’s a novel design that moves away from the one-fit-for-all approach of the bourgeoning bed-in-a-box mattress market. And it isn’t just aimed at pain sufferers. The Nrem mattress has been designed to help every individual sleep better. Tweak reckons 94% of customers have improved their sleep after just one night. On paper, it sounds great. So how good are Nrem’s interchangeable inserts? We put it to the test.

Tweak Nrem mattress: materials

The Tweak Nrem mattress comprises five layers. On top is a breathable, hypo-allergenic fabric cover that (hooray!) can be removed and machine washed at 30 degrees. Next, there’s a 4cm Revo “cooling comfort layer” that cushions your body, while also wicking away moisture and preventing you from overheating. 

The headline feature – the customisable reflex foam inserts – sits in the middle. (Our review mattress came with four soft, four medium and two firm, but you can choose different densities and buy additional inserts when you order.) What's so good about reflex foam? Well, it reacts faster than memory foam, moulding instantly to your body when you move, giving you better support and avoiding the sinking feeling that can come with memory foam mattresses. 

The Tweak Nrem mattress has five different layers

Underneath this is a layer of 1,000 individual pocket springs for extra support. These move independently, so you won’t feel your partner tossing and turning. Finally, a foam base encapsulates the springs, giving edge-to-edge support.

Tweak Nrem mattress: set up

Our double Nrem mattress was delivered vacuum packed and tightly rolled (not in a box) by two cheerful delivery men, who carried it upstairs for us. At 30kg, it’s possible for one person to lug the double onto a bed base, but you’re better off manoeuvring the mattress with two people – especially if you’ve chosen it because you suffer from chronic pain.

We didn’t notice an odour after the mattress was unwrapped, although some users have. That's normal though – just keep a window open and the smell should dissipate within a few hours. Like all bed-in-a-box mattresses, the Nrem needs to expand before you can sleep on it, so we left it for six hours before arranging the inserts and adding bedding.

Girl swapping the Tweak Nrem mattress inserts

It takes less than five minutes to configure the Tweak Nrem mattress

In practice, configuring the mattress was a straightforward process. The stretchy cover zips open and closes easily, and the foam inserts are corrugated on the underside, so you just slot them in the order you want onto the base below. Bear in mind that the foam does have a lot of friction, so you can’t just slide the inserts in, but positioning each insert is easy. 

Tweak suggests starting with one of the following setups:

Tweak sends a handy setup guide with every Nrem mattress

Our reviewers set up one side for lower back pain, and the other for a medium-firm general preference. 

Tweak Nrem mattress: comfort

We found the Nrem mattress to be exceptionally comfortable, and supportive in all the right areas. The reactive foam provides instant support, responding to movement and remoulding immediately. Our reviewers saw their sleep improve on the first day of testing, and one reviewer with lower back pain found that his back felt noticeably better after a week or so of sleeping on the mattress. 

We particularly liked the absence of transferred movement. If you have a partner who’s prone to tossing and turning, you’re not going to feel them moving. (Unless they have a habit of flailing around, but that’s a whole other problem.) We also loved being able to tailor the mattress to our own preferences: not having to compromise on firmness is a game-changer. 

Hand pushing down on the Nrem mattress

Reactive foam responds faster to movement then memory foam, providing improved comfort and support

It's worth noting that for one of our reviewers the mattress felt a little warm. Their sleep still improved while testing the Nrem, so the impact was minor. However, a small number of user reviews online also make the same observation, so it’s something to be aware of if you’re prone to overheating. 

Whether the Nrem will succeed in its mission to help chronic pain for everyone is harder to review because pain is subjective, and can change over time – but that's the point of this mattress: you can rearrange it. Tweak says: "Whilst the mattress can not cure chronic pain conditions, it can help you to get more comfortable at night, giving you a better night's sleep." Certainly our experience was positive, and independent reviewing bodies like Trustpilot have collated scores of happy reports from customers, many of whom had been at their wit's end with neck and back pain. 

Should I buy the Tweak Nrem mattress?

The Nrem mattress gets our vote for anyone with back or neck pain. It’s also a fantastic solution for anyone who’s tired of compromising on the firmness of their mattress, or shares a bed with a restless partner. With phenomenal support and customisable comfort, we think it’s a winner. (Tweak also sells a sleep tracker, so you can monitor how effective the mattress is, as well as receiving pro sleep tips.)

Forget memory foam – the Nrem mattress uses luxurious reactive foam the moulds immediately to your body

Naturally, it isn’t the cheapest – the Nrem mattress sits at the top end of the mid-range market. If your budget won’t stretch that far, take a look at the Eve mattress in our best mattress round-up, which is currently selling on Amazon for under £450 for a double; or the award-winning Emma Original, which is even cheaper again right now, at £390 for a double on Amazon.