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A duvet designed to fight hot and sweaty sleep — from Casper Labs.
1,034 backers pledged $351,686 to help bring this project to life.
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What is a prototype?

A prototype is a preliminary model of something. Projects that offer physical products need to show backers documentation of a working prototype. This gallery features photos, videos, and other visual documentation that will give backers a sense of what’s been accomplished so far and what’s left to do. Though the development process can vary for each project, these are the stages we typically see:

Proof of Concept

Explorations that test ideas and functionality.

Functional Prototype

Demonstrates the functionality of the final product, but looks different.

Appearance Prototype

Looks like the final product, but is not functional.

Design Prototype

Appearance and function match the final product, but is made with different manufacturing methods.

Production Prototype

Appearance, function, and manufacturing methods match the final product.

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Prototype Gallery

These photos and videos provide a detailed look at this project’s development.

Feeling hot and sweaty while you sleep? We designed the first duvet to fight the humidity that keeps you up at night. 

Based in San Francisco, Casper Labs is Casper’s specialized R&D faction. We’re always working to find simple solutions to complicated sleep problems. Last year, after months of research, we brought an all-season duvet to market. But a few of us couldn’t stop there. We wanted to dive deeper into the microclimate of sleep, exploring heat indexes, dew points, and variances. This Kickstarter is our opportunity to get early feedback on an experimental new design that we’d like to eventually bring to  

The Problem: Humidity is Wrecking Your Sleep

One of the most common sleep problems? Most people say they sleep too hot — or so we thought. We conducted months of sleep testing to understand what made fitful sleepers toss and turn. Once we stabilized temperatures, we discovered that humidity was the real culprit. Uncomfortable moisture buildup is what really causes people to toss, turn, and throw off their covers.


The Solution: A Humidity Fighting Duvet

To stabilize humidity and reduce sleep disruptions, we harnessed the moisture regulating power of Merino wool and carefully combined it with the insulating properties of down. The result: a patent-pending duvet that keeps you consistently warm and cozy, but never clammy.

The Research Process

We spent over a year doing research. Our process focused on understanding the relationship between temperature and humidity under the covers and ambiently in the bedroom. We developed our own sleep sensor kit and put it to work:

After months of collecting data, an intriguing pattern emerged beneath the covers. We would generally see a sharp spike in humidity and then an immediate drop in temperature. Video analysis showed that this drop was almost always caused when overheated testers tossed off the covers. If humidity were kept stable, the need for mid-night cover wrestling would be reduced.

Introducing Wool Had Near Magical Effects

The below illustrates our consistent findings across even some of our earliest prototypes.  Amazingly, just a thin layer of wool could reduce the humidity under the covers to be in-line with, or below, a bedroom’s ambient humidity. A down only construction had the opposite effect:

Balancing the Amount of Wool

While wool clearly helped with moisture regulation, too much wool would make the duvet too heavy. We calculated the right balance by studying average moisture loss of men and women during a night’s sleep, and how much wool was needed to absorb a sufficient amount of it. We balanced this with the breathability of the weave of the cotton shell and the amount of down insulation in the duvet's chambers.

Making Our Own Wool Textile

We already knew about Merino wool’s incredible properties from the performance apparel industry and so it was natural to explore whether we could improve its properties with other materials. In the end, we engineered a unique 85% merino, 15% low-melt synthetic fiber textile that holds the wool fibers evenly and securely together. This combination allowed us to keep the wool layer relatively thin as well as ensure a consistent evaporation profile throughout the duvet.


Deep Dive: Wool, Down, and Cotton.

1. Not your Granny's Wool

The Casper Merino Wool Layer is superwashed and very lightweight (100 grams per sq. meter). Merino fibers are finer than normal wool and they are also more flexible. The duvet's wool fibers have a less than 30 micron diameter and are blended with a super fine polyester fiber (85% wool, 15% low melt polyester) and then baked. The polyester melts to create a matrix structure that holds all the wool fibers together in a unique new fabric.

A Merino Sheep
A Merino Sheep

Key factors we considered and customized:

  • Wool Fiber Micron Diameter 
  • Wool Weight
  • Moisture Regain
  • Evaporative Resistance
  • Thermal Resistance
  • Sourcing Techniques - we will source the wool from suppliers who comply with The Responsible Wool Standard.

2. Cruelty-Free Duck Down

Unique to waterfowl birds, the down cluster is an amazing inner coat that helps them stay warm, buoyant, and keep their eggs warm during nesting. The cluster has no hard quills (like feathers) and has many fluffy filaments growing in all directions. These soft puff balls are perfect for holding air and insulating.

When blown into the duvet, these clusters form a wonderfully light matrix that traps air to help maintain temperature while still allowing excess moisture and heat to pass through.

Fill Power is the measure of down’s fluffiness or fullness. The higher the fill power, the more volume a given weight of down can fill. Finding the right proportion of fill power and fill weight is key to creating a duvet that is warm yet lightweight. 

We used down with a fill power of 750 to achieve the best balance of weight and insulation possible.

3. Down-Proof Cotton Shell

People tend to focus on the weight of down, but the fabric shell actually makes up most of a duvet’s weight. So, we worked to craft a cotton shell that’s 35% lighter than typical cotton shell fabric. 

Duvet shells need to be woven tightly so that the fluffy down can’t escape. By decreasing the yarn diameter and increasing the woven density of the fabric, we created a tighter barrier that doesn’t compromise air flow.


Design and Development

In researching hundreds of duvets, we found that there are two main construction methods:

Baffle box duvets use a grid of square boxes with internal walls to create a consistently thick and puffy cloud look that consumers love. These internal walls have flaps through which the down is filled into the boxes.

Sewn-through duvets are much simpler, with two layers of fabric stitched together to create pockets (usually square) for fill.

Despite baffle box being the most common duvet construction, it’s more complicated to fabricate and limits the design to a square box. Plus, as time goes on and the duvet goes through wash/dry cycles, down will migrate between boxes (via the flaps on the internal walls) and likely get overly full at the base of duvet—there is no way to fix this. 

Our in-house testing confirmed that the temperature variance between the complex baffle box and simpler sewn-through constructions was negligible for an indoor environment like the bedroom. Just to be sure, we duplicated the test at the Institute for Environmental Research at Kansas State University using a temperature-controlled guarded hot plate device. (Same results!) 

When we sleep-tested and ranked the various competitive duvets, the sewn-through construction also rated as our top pick. So, we moved forward with the sewn-through method to ensure a long-lasting and consistent distribution of down, while also giving us the freedom to explore the best size and shape of pocket. 

May 2016 - early testing of manufacturability.
May 2016 - early testing of manufacturability.


August 2016 - Identifying our wool supplier
August 2016 - Identifying our wool supplier


September 2016 - First full-scale prototype. We made a few of these testing the balance of wool and down.
September 2016 - First full-scale prototype. We made a few of these testing the balance of wool and down.


November 2016 - hot-plate testing prototypes. We made lots of these and designed them to host multiple sensors.
November 2016 - hot-plate testing prototypes. We made lots of these and designed them to host multiple sensors.


March 2017 - Durability and wash-test prototypes that we sent to a lab for rigorous testing.
March 2017 - Durability and wash-test prototypes that we sent to a lab for rigorous testing.


The Duvet's Construction
The Duvet's Construction


June 2017 - Lab dip dye samples for the gray fabric shell
June 2017 - Lab dip dye samples for the gray fabric shell


June 2017 - Defne tests a production prototype.
June 2017 - Defne tests a production prototype.


A New Type of Sewn-through Duvet

During the typical construction process of a sewn-through duvet, the stitching happens after the filling, which means the down fill can get trapped between the stitching. To avoid trapping our precious down clusters, the majority of our sewing happens before the down is added.

After sewing the structure of the duvet, our down is blown into those pre-sewn channels. We then use minimal sewing across the narrow channels, creating smaller pockets with less trapped down. 

These narrow channels are fantastic for keeping the down in place, on the core of your body, without migration or cold spots. Narrow channels also drape nicely from head to toe and side to side.


This technique is similar to those used in down jacket construction. Most down jackets look like this because horizontal channels keep the down in place across your entire body.


Finishing Touches

We added corner loops to work with the existing Casper Duvet Cover snaps, which hold your cover on nice and tight. We also use the Casper label to make it easy to identify the head and toe of the duvet.

Finally, we decided to make one side of the outer shell gray to differentiate between our down-only duvet.


Technical Details 

Project Timeline

The wool duvet started as a spin-off exploration from our more traditional all season duvet:

  • 1/16 First temp/RH sleep sensor data 
  • 3/16 Wool Duvet Shell
  • 5/16 First manufacturing viability sample 
  • 8/16 Identify Wool Supplier 
  • 12/16 Sweating Hot Plate 
  • 1/17 Approve gray lab dip 
  • 3/17 Durability/appearance testing/BV 
  • 3/17 Duvet Assembly Construction Finalized 
  • 3/17 Finalize down spec 
  • 4/17 Finalize Wool Spec 
  • 5/17 Down Duvet Launch 
  • 6/17 Fabric production started 
We are here -------->
  • 8/17 Finalize production spec  
  • 8/17 Shell cut+sew  
  • 9/17 Shells on the water 
  • 10/17 Down filling + finishing  
  • 11-12/17 Ready to ship

Who We Are

2 years ago, Casper Labs set out to create the “skunkworks of sleep.” Our goal is to develop thought-provoking solutions to age-old problems related to sleep. Now 32 people strong, the team has experience innovating in nearly every industry, from cars to space.

Why Kickstarter?

Casper encourages our team to experiment and try new things. We wanted to launch this controversial design to a community that would appreciate the design work and provide us with the kind of feedback that would help us bring a new product to market.

About Casper

Casper (​​) is dedicated to exploring the frontiers of sleep. In 2017, Casper was named one of Fast Company’s Most Innovative Companies in the World. We are also a registered B Corp.


Video Score: "Something Elated" by Broke For Free is licensed under CC BY 3.0 US / Edited from original



Risks and challenges

Our plan is to have supporter's duvets shipping by mid-November but we've put December to be on the safe side.

If the project goes far beyond our expectations, there is a mild chance that later supporters will receive their duvets in January or February. We will proactively message this.

Learn about accountability on Kickstarter
Questions about this project? Check out the FAQ

Funding period

- (54 days)

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