They are some of the most overlooked pieces of furniture – mattresses. No one really thinks about their mattress. They merely lay there every day, hidden away under sheets and blankets. However, these often-forgettable objects can have a significant impact on your health. They can harbor allergens, cause muscle pain, and even increase the frequency of illness. In fact, a bad mattress can be bad for your overall health. You should replace your mattress every five to 10 years.