Sleep warmly—without sweating—with Casper's new humidity-fighting duvet insert. 

By Lauren Phillips
Updated September 10, 2018
Casper Humidity Fighting Duvet cover review - bed with duvet cover
Credit: Courtesy of Casper

The Humidity Fighting Duvet from Casper—yes, the same geniuses behind the now-iconic mattress and sleeping innovations such as the nap pillow—has a fancy name, but fancy names aren't the be all end all when you have a hard time sleeping. Fortunately, this duvet insert more than meets expectations.

I had the opportunity to test and review this Casper duvet insert in the throes of summer. Not the best time to be using a duvet, of course, but I was able to test the duvet insert’s humidity fighting claims whilst surrounded by what felt like a wall of damp summer heat—and I was pleasantly surprised.

I (incorrectly, I now understand) thought all duvets were made alike. I didn’t expect this one would make trying to sleep through a hot summer’s night any easier, but somehow, it did. Plus, when I woke up in the morning, I felt less sticky and damp than usual. Deeper sleep and a more refreshed feeling in the morning–what’s not to love?

Of course, like everything Casper does, there’s a ton of science behind the making of this duvet. This humidity-fighting duvet insert from Casper (To buy: From $350; is made of a combination of fluffy down, lightweight cotton, and a layer of merino wool. This wool layer absorbs moisture and naturally regulates temperature, allowing the duvet to strike a balance between keeping you warm and making you stuffy.

In addition to its miraculous humidity-fighting powers, this Casper duvet insert is designed with rectangular chambers that keep the filling evenly distributed, so no more aggravating bunching. The down fill is sourced ethically, and the shell is 100 percent cotton. The insert even has corner loops for use with Casper’s duvet covers (such as the Weightless Cotton duvet cover, from $60;, to keep the insert from shifting within the cover.

The Humidity Fighting Duvet launched in August as part of Casper’s new bedding shop, which includes Cool Supima and linen sheets, a mattress protector, an airy linen quilt, and more. All items are available in a range of quiet, soothing colors that will further contribute to the zen-ness (and comfort) of your sleep space.