Jeans and sweats are made of cotton or cotton blends, and will absorb and retain moisture, leaving you wet, cold, and weighed down. PolarBearWear fleece actually wicks moisture away from your body, keeping you warm and dry. It's all those things listed above. So it helps prevent hypothermia. Not all synthetic fleece is the same.
Some fleeces are a blend of cotton with polyester or acrylic or both.
Cotton is perfect for those hot summer days, but for winter wear it can be dangerous. It absorbs and retains moisture, which contributes to chilling and hypothermia. Water conducts heat away from the body 25 times faster than air. Stay dry and stay alive. For the safest winter wear choose a fleece product that contains no cotton.