How often do you clean your mattress and pillows?

Last week, I saw the Oprah show from abc channel. It was about the topic "How Often Do You Clean Your Mattress and Pillows?". According to their findings, we should regulary clean our mattress and pillows once a week. Why? Because there might be dust mites. If you ignore the cleanliness, then you are not sleep alone. This really makes me aware of the importance of hygiene of our surroundings to our health.