A research study carried out using the Tweak: Nrem mattress.

We collected over 7,000 hours of sleep data to determine how mattress zoning can help to improve sleep. Our participants slept on the Tweak: Nrem mattress using a variety of different set-ups, tailored to their needs. 

We know that buying a mattress can be confusing and, not to mention, awkward - lying on a mattress in a store for 5 minutes, whilst being watched over by a salesperson bears no resemblance to sleeping on it for 8 hours at night. It’s an impossible decision to make in such a short space of time, and often couples have to compromise on comfort to please a partner. 

We are all different

We have different needs, preferences, height, weight and body shapes, so what is comfortable for one person, may not be for another. A petite female may require a softer mattress than a gym-loving, larger male, for example. 

Good quality sleep is vital for a healthy life. We spend one third of our lives in bed, so nobody should compromise when it comes to their mattress. 

The science behind mattresses.

The mattress industry is long-established, however there is very little scientific data which helps people to choose the right mattress for them. Some retailers have over 100 mattresses on offer, an overwhelming number of products for even the most determined shopper to browse. 

Over the past few years, the industry has been interrupted by a new way of buying. The ‘mattress in a box’ concept allows you to buy a mattress online with fast delivery. You can sleep on it in your own home for up to 100 nights before committing to it. 

The Tweak Mattress Design

Different cultures have different preferences for a mattress (American’s often prefer soft whereas Chinese often prefer firm), but it is not only personal preference that determines the ideal mattress for one person. Sleeping position, body shape and weight are all important variables.

You are the expert in You

Nrem mattress setup couple

Because of different firmness preferences and requirements, the only realistic solution was to allow every sleeper to self-select their firmness levels. Not only this, with the Tweak mattress, sleepers can have a different level of comfort or support for particular body parts using the 5 interchangeable comfort zones from head to toe - an ideal solution for pain sufferers and back/front sleepers.

Initially, individuals were asked to change their mattress configurations to find their preferred set-up, however, we quickly learned that only the best-motivated people were willing to experiment, whilst the majority preferred to be recommended a customised set-up. 

We found it difficult to recommend what people may need as there was little reliable data available - thus prompting our research.


We wanted to find out:

  1. Do people sleep better on a Tweak mattress, and is that significant?
  2. What set-ups were most successful, and could we explain why?

The Tweak Nrem mattress

Tweak is made with pocketed springs at the core, then a layer of interchangeable foam inserts of high quality and varying firmness and performance. This is topped with a comfort layer made from a soft, pressure relieving memory foam which contours the body and evens out the difference between the interchangeable inserts in the layer beneath. Tweak is manufactured in the UK by a reputable healthcare bed specialist.

Inside Nrem mattress

Previous research

We ran an extensive customer survey to investigate preferences, body shapes and size as well as customisable support set-ups and found that 68% of people sleeping on the Tweak mattress have a different level of support in the torso compared with the hips (the 2 key weight-bearing zones).

Participant recruitment

  1. We focussed recruitment on those who weren’t actually looking to purchase a new mattress to avoid any ‘new mattress improvements’.
  2. We recruited a combination of participants with and without ailments including Scoliosis, Hip Pain and Back Pain.
  3. Participants’ gender was balanced at M/F = 13/12.
  4. 2 couples were removed from the final results due to inaccurate data.
  5. Participants included a doctor, dentist and 2 physiotherapists.


Participants completed a daily sleep diary for up to 2 weeks before sleeping on a Tweak mattress to gather baseline data about their sleep. They then completed a further 4 weeks of sleep diaries whilst using the Tweak mattress to measure any changes in their sleep. We collected over 1,000 sleep diaries in total.

Participants also completed a variety of sleep questionnaires and provided body and health data and were only shown their sleep data once the trial had been completed to minimise bias. 

Mattress set-ups

To avoid ‘over-coaching’ participants, we discussed their sleeping positions and ailments and then referred them to the website to find various suggested set-ups. Participants were encouraged to experiment and find their ideal set-up, and informed us whenever the set-up was changed. 


  1. Overall, the sleep average showed substantial improvement of an additional 29 minutes sleep per night.
  2. Only 3 couples chose a comfort set-up which used the same firmness level underneath the hips and shoulders, and on both sides. The mattress in a box model of ‘1 comfort fits all’ is, therefore not supported by this research.


See the mattress at