Why did cotton keep heat in the best?

Cotton retains heat effectively due to its natural fiber structure, which traps air and creates insulation. The fibers have a high moisture absorbency, allowing them to keep warmth close to the body while also managing humidity. Additionally, cotton's soft texture enhances comfort, making it a popular choice for clothing and bedding that requires warmth. However, while cotton retains heat well, it may not be as effective as some synthetic materials designed specifically for insulation.