This is possible because wool is a natural wicking fiber. The wool fibers actually allow moisture to pass through without retaining any of the moisture in the wool itself. Mold and Mildew cannot survive without a damp environment to grow upon. Furthermore, the only way that mold or mildew can grow on wool is if the wool is immersed in water which wouldn't allow for air circulation.
Wool Has The Ability To Regulate Temperature
Wool fibers keep a pocket of air close to your body. The coil-shaped fibers naturally wick excess heat and moisture from your skin and create an optimal temperature zone for a good night's sleep.
Wool Keeps Your Heart Rate Low
A study conducted by scientists at the Polytechnic Institute of Wales measured the effects of many fibers on human subjects as they slept. Not only did they find that the wool fibers tended to keep the skin drier, they were amazed to discover that the subjects using wool-fill comforters actually had lower heart rates. A lower heart rate indicates that the sleeper is in a deep, relaxed state. The test subjects with other fibers either maintained the same heart rate or exhibited an elevated rate.
Wool Is Mostly Non-Allergenic
Our wool is processed without the use of any harsh chemicals such as Chlorine or moth-proofing chemicals. Though a few people have a natural allergy to lanolin (an oil found in wool) most allergic reactions are caused by the toxic chemicals that are used to create wool garments or bedding. We use cotton fabric to cover our bedding and don't have the problems with mold that other fillers can have.