All over your home, and especially in your pillows and duvets, lie creatures you can neither see nor hear. They are house dust mites, and they are everywhere. These strange, prehistoric-looking insects live where humans live, thrive on the tiny flakes of skin that constantly shed off of our bodies and can cause serious health problems, including allergies and debilitating asthma.

Due to their tiny size, house dust mites are almost invisible to the human eye. Males live an average of 10 to 19 days and females live up to 70 days, busily producing as many as 100 eggs. Thus, mites reproduce rapidly. In the same class as spiders (arachnida), house dust mites have translucent exoskeletons and a somewhat crab-like appearance.

House dust mites favor moisture and fabrics and are found in the greatest concentrations in pillows, duvets, mattresses and carpets. Polyester-filled pillows make better homes for dust mites than feather pillows, but both can attract mites and their feces over time. On average, polyester-filled pillows accumulate more than double the quantity of mite allergens compared to feather-filled pillows. One 1996 study published in the British Medical Journal concluded that asthma sufferers face a greater risk of reactions to mites with synthetic-filled pillows.

Mites produce potent digestive enzymes that are allergenic to humans. These enzymes, especially those which break down proteins, produce allergies so common that they have been extensively studied worldwide. As many as fifteen different dust mite allergens have been identified by researchers. Itching, sneezing, red and inflamed skin, wheezing, sinus congestion and asthma can all be caused by the presence of dust mites, and by residual mite feces, which also contains the allergenic enzymes produced in the guts of these creatures.

A common myth concerning house dust mites is that the accumulation of their feces can add pounds of weight to pillows. There does not seem to be scientific consensus on this, as studies both support and refute this claim. However, the presence of mites and their feces in bedding is a well-documented cause of allergic disorders, especially among children. Many dust mite therapies have sprung up to combat these allergies, and various drugs are currently in development to address the problem. Currently, anti-histamines and steroid drugs are administered to relieve mite allergies. However, both classes of drugs carry the risk of some negative side-effects and cannot be relied on as long-term solutions.

To help reduce mite allergies, vacuum carpets and couches regularly, especially under and behind pillows. Wash all bedding on a regular basis, including pillows and duvets. Use hot water and some bleach to eradicate the mites. Drying on high heat will also kill mites, thereby ending their reproductive cycle.

Additionally, home HEPA (high efficiency particulate absorption) air filtration units can remove house dust mites and micro-particles of their feces from the air, creating a safer breathing environment. Some vacuum cleaners also contain micro-particle filters, and can help to reduce mite populations and mite-related particles in the home. Using these types of vacuums on mattresses can also help to reduce mite concentration.

Homes with wall-to wall carpeting are especially excellent breeding grounds for house dust mites, whereas hard, wooden floors provide a poor environment for mites to flourish. In cases of severe mite allergies in the home, carpeting may need to be removed entirely.

Sublingual immunotherapy, involving the administration of minute doses of specially-prepared allergens under the tongue, has shown great promise in those suffering from mite allergies and mite-induced asthma. Though common in Europe, Asia, South America and Australia, sublingual immunotherapy remains uncommon in the US, largely due to poor profitability. Nonetheless, of all known therapies employed at this time, sublingual immunotherapy appears to be the most effective.

Though mites are practically invisible, their impact on human health is significant. In warmer weather, maintaining a good flow of outside air in a home or office environment with open windows and doors can reduce the density of mite allergens in the air. The Asthma and Allergy Foundation of America also offers advice that can help control mite allergens in your home.