Swisswool: Our Natural, Breathable Wool

Almost every baby sleeping bag on the market is filled with polyester — a plastic fiber that traps moisture instead of wicking it away. Swisswool is our answer: a natural, breathable wool filling developed specifically to help you and your baby sleep better. Here's what it's made of, how it works, and how it compares to down.

​What Is Swisswool Made Of  |  ​Why Breathability Matters  |  ​Wool vs. Down  |  ​FAQ

What Is Swisswool Made Of?

Swisswool is a patented, natural filling made from 88% virgin wool from Swiss sheep, reinforced with 12% plant fibers that make it fully machine washable without losing any of wool's natural properties.

It's also a local and sustainable material: farmers bring raw wool to collection points around Switzerland, where the fleeces are sorted by quality. Only the finest grades are selected to become Swisswool for ​Zizzz products.

Why Breathability Matters for Sleep

A breathable ​baby sleeping bag lets air and moisture pass through it, keeping your baby's body at the right temperature so they don't wake up at night. The result is deeper, more relaxed sleep — for baby, and for you.

Here's how it works: wool fibers can absorb up to 35% of their own weight in moisture, pulling it into the core of the fiber and leaving the outside dry. Polyester, by contrast, absorbs only about 3% — the moisture stays trapped between the fibers and your skin, leaving a clammy feeling. Wool fibers also contain millions of tiny air pockets that provide natural insulation, keeping the body warm when it's cold and cool when it's hot.

Wool vs. Down: Which Is More Breathable?

Down is also breathable, but it works differently — and it's warmer. Its snowflake-like clusters are mostly empty space, which traps warm air and makes down an excellent insulator. When sweat touches one of a cluster's hairs, part of that moisture transfers to the surrounding hairs and dissipates once the duvet is no longer in contact with your body.

That's why it's worth shaking out a down duvet each morning — it loosens any clusters that clumped together overnight — and airing it out on dry days to release any trapped moisture. Down's one real enemy is oversaturation: when wet, it loses much of its insulating power. Our down duvets are machine washable, but always add a few tennis balls to the dryer so the down doesn't clump as it dries.

Frequently Asked Questions About Swisswool

What is Swisswool made of?
Swisswool is a patented natural filling made from 88% virgin Swiss wool and 12% plant fibers, which reinforce the wool and make it fully machine washable.

What is the difference between Swisswool and a polyester filling?
Swisswool breathes and wicks moisture away from the body, helping regulate temperature for deeper, more comfortable sleep. Polyester, a plastic fiber made from oil, can't absorb moisture the same way — it stays trapped against the skin, leaving a clammy feeling.

What are the characteristics of Swisswool?

Characteristic	Why it matters
100% natural	Made from real Swiss sheep's wool, not a plastic-based fiber
Breathable	Lets air and moisture pass through instead of trapping heat
Regulates body temperature	Keeps you warm when it's cold, cool when it's hot
Local and sustainable	Sourced and processed close to home, reducing environmental impact
Toxin-tested	Safe against your baby's sensitive skin
Hypoallergenic	Gentle on sensitive skin and allergy-prone sleepers
Naturally odor-resistant	Stays fresh longer between washes
Machine washable at 30°C	Easy to care for, just like any regular fabric