Commonly, sheets begin to smell because of mildew, particularly if they've been improperly stored in a damp area. However, the breathability of Amerisleep's bamboo sheets means that they will resist odors from sweat when in use. When the sheets aren’t on your bed, we suggest keeping them in a cool, dry place to best maintain their condition. The bamboo fibers also have antibacterial and antifungal bio-agents that will keep smelly bacteria and mold spores from making themselves comfortable inside the sheets.