What the Research Found: Wool vs Down, Feather and Synthetic
- Wool duvets have better insulation properties than down, feather and down, and synthetic duvets, meaning wool will keep you warmer at night
- Wool duvets maintain a consistently warmer temperature than other fibre types, meaning wool will keep you warmer over a longer period of time
- Wool duvets transmit significantly more moisture than other fibre types when simulating sweat wicking away from the body
- Wool duvets absorb less moisture than other fibre types and move moisture much faster too, helping to keep you more comfortable as you sleep
- As the experts in wool bedding, we are delighted to see wool emerge as the superior fibre for deep, restorative sleep in comparison to other bedding fibre types and hope this research will have a hugely positive impact on UK wool trade
Ever woken up in the middle of the night feeling clammy, kicking off the covers only to feel the chill moments later? You aren't alone. This cycle of overheating and cooling is one of the most common causes of disrupted sleep. But what if the problem isn't you, but your duvet?
New research released by British Wool, and conducted in collaboration with the International Wool Textile Organisation (IWTO) has examined how different duvet fillings perform when it comes to temperature regulation and moisture management.
The study was carried out at the BioComposites Centre at Bangor University, with funding from the Welsh Government and industry expertise contributed by IWTO members, including our managing director and resident sleep expert Chris Tattersall.
Methodology
The aim of the study? To compare two key components of duvets filled with different materials:
- the thermal performance
- the humidity response
The goal was to determine the best bedding fibre of duvets to promote the best sleep.
The testing was conducted on full-sized single duvets of similar tog ratings (10-10.5 Tog) from products readily available in the UK retail market, composed of the following fillings:
Wool
Synthetic
(Polyester)
Feather and Down
(85% Feather and 15% Down)
Down
(100% Down)
How Wool Regulates Temperature During Sleep
One of our favourite benefits of sleeping with a wool duvet is its temperature regulating properties – it keeps you warm when it's hot and cool when it's not. But just how well does it perform against its rivals?
Testing How Well Each Duvet Insulates
In the latest Bangor University study, the thermal performance of each bedding fibre was tested using a FOX 300 thermal conductivity meter, which has heated upper and lower plates (think hair straighteners!)
A 30cm x 30cm sample was cut from each duvet and placed between the heated plates. Each of the samples were conditioned to ensure the same temperature and humidity to begin with. The thermal conductivity was then measured, producing a K-value (or thermal conductivity co-efficient).
In simple terms, materials with a lower K-value do a better job of keeping warmth in — which is why K-value is commonly used to compare insulation performance.
The Insulation Study Below Shows That Wool Is...
1
%
better insulation than synthetic duvets
1
%
better insulation than feather and down duvets
1
%
better insulation than down duvets
Insulation Results: Wool Outperforms Other Fillings
With the lowest K-value of all, wool came out as the most efficient insulator, meaning it will keep you warmer than when sleeping under down, synthetic and feather and down duvets.
Due to the nature of wool fibres, wool duvets tend to be less lofty than other fibre types, and these results demonstrate that wool duvets are better insulators than other fillings, even if they appear thinner than other duvets.
Testing Temperature Stability Under Overnight Sleep-Like Conditions
Thermal performance was also tested over time, replicating a situation in which a person sleeps throughout the night.
Data loggers were used to measure temperature gradients from a warm side (30 degrees Celsius) to a cold side (10 degrees Celsius) of each duvet over a period of eight hours. The data loggers were positioned just inside the covering material at the top, bottom and in the centre of the duvet. The temperature was logged every minute, with mean values determined for each hour of exposure, for three replicates.
Temperature Stability Results: Wool Retains Heat More Consistently than Other Fillings
Testing How Quickly Duvets Warm
In order to find out the speed at which each of the duvets warmed, the study simulated someone getting under the duvet, by logging the temperature of each duvet as a plate gained warmth.
Temperature readings were recorded every second for five minutes, with data loggers placed at the bottom and centre of the duvets, and results taken from the bottom of the duvet where the sleeper lies.
How Wool Manages Moisture While You Sleep
The second component of the study aimed to test the level of moisture management of different bedding fibres. Thanks to the tiny air pockets in the structure of wool fibres, wool is able to wick sweat away from the body at night, making it an excellent fibre for hot sleepers. Let’s find out just how much moisture wool can transport.
Testing How Well Duvets Manage Moisture
In this test, a water bath was filled with water and heated to 37 degrees. The surface of the bath was covered by a sample of each duvet, cut to 35cm x 35cm and fixed using a waterproof sealant to ensure the duvet did not contact the water’s surface.
After a period of 24 hours, the sample was removed, and the change in weight due to the level of water absorbed was determined. By measuring water loss from the bath, the study was able to identify how well the different fillings allow moisture to ‘breathe’ away.
Moisture Management Results: Wool Holds Less Moisture and Releases More
Wool significantly outperformed all other materials, with the lowest amount of moisture held, and the highest amount of moisture transmitted. This shows that a wool duvet will not absorb sweat and will work hardest to transmit this away from your body, allowing for the most comfortable night’s sleep.
When the temperature of the water was raised to 50 degrees Celsius to simulate sweating, the results were even stronger. Wool continued to outperform down, feather and down, and synthetic bedding when it comes to temperature regulation, moving significantly more moisture than other fibres.
What Does this Mean?
When you are too hot, your body regulates its temperature by sweating, and the evaporation of perspiration cools your body. The faster the moisture can be transported through the duvet and away to the outside air, the more effectively your body’s natural cooling can work
If moisture movement is slow, this leads to high humidity in the bed and a feeling of hot, clammy and discomfort. The better the moisture buffering and movement, the better it works with your body’s natural cooling.
If your duvet is working to regulate your temperature, wick sweat and moisture from your body and help you to remain cool, this all means that you are less likely to wake up throughout the night due to discomfort, meaning that you will gain a deeper, more restorative sleep with wool.
Holding Moisture
| Comparison | @37°C | @50°C |
|---|---|---|
| Wool holds less moisture than synthetic | 45% | 14% |
| Wool holds less moisture than feather | 75% | 40% |
| Wool holds less moisture than down | 37% | 22% |
Transporting Moisture
| Comparison | @37°C | @50°C |
|---|---|---|
| Wool transports more moisture than synthetic | 110% | 139% |
| Wool transports more moisture than feather | 88% | 151% |
| Wool transports more moisture than down | 10% | 50% |
Based on Testing at Elevated Temperatures, Wool Duvets Move Moisture:
1
%
quicker at moving moisture than synthetic duvets
1
%
quicker at moving moisture than feather and down duvets
1
%
quicker at moving moisture than down duvets
*these percentages are based off the 50°C testing
Testing How Quickly Duvets Move Moisture
This test aimed to show the speed of transmission of moisture through the duvet. Temperature values were logged every minute, with mean values determined for each hour of exposure over eight hours.
Moisture Transmission Results: Wool Moves Moisture Faster than Other Fillings
The higher the number, the faster the moisture is transmitted. This means that not only does wool remove more moisture than other fibre types; it does so much faster than other materials.
Bangor of a Sleep Guarantee
Discover our dreamy wool duvet range and experience truly life-changing sleep. Explore the duvets below to find the perfect option for you, designed to help you sleep deeper, longer, and more comfortably every night.
To support our Bangor Sleep Guarantee, anyone who orders a Woolroom duvet between 29th January and 1st October receives a 60-night, no-quibble guarantee. Sleep on it at home and, if it’s not right for you, simply return it.
Our promise is backed by research showing wool outperforms down, feather and down, and polyester in creating the ideal environment for deeper, more restorative sleep. In short, we’re confident in wool and we’re putting our money where our mouth is.
