After dealing with blood hungry bedbugs, mosquitoes and fleas, dust mites seem tame. They're related to spiders, but on a tiny scale. They don't bite, and at less than 1/100 of an inch long, their major negative contribution is that their waste -- as in, dust mite feces -- causes allergies and asthma problems. They feed on dead skin cells, and humans shed lots of skin -- somewhere in the neighborhood of 30 to 40 thousand skin cells each and every minute.
You can help keep dust mites under control by using a high-efficiency air filter and reducing the humidity in your home. You should also wash your bedding weekly and vacuum regularly. Dusting daily is a good maintenance strategy, too.
If it's starting to look like there's more wildlife in your bedroom than in your backyard, relax. Even with a few baddies trying to munch on you when you're not looking, you're usually still better off in the relative safety of your own home.