House dust mites are the most common environmental trigger for eczema, and the bedroom is the primary exposure site because you spend seven to nine hours a night in continuous contact with bedding that can harbour millions of them. The single most effective intervention is allergen-impermeable covers with a pore size of 6 microns or less on the mattress, pillow, and duvet, combined with weekly bedding washes at 60°C and keeping bedroom humidity below 50%.
What dust mites are
House dust mites are microscopic arachnids that live in soft furnishings, particularly bedding, mattresses, carpets, and upholstered furniture. They feed on shed human skin cells. A typical mattress contains between 100,000 and 10 million dust mites, depending on age, humidity, and cleaning history.
Dust mites don't bite or sting. The allergenic response they trigger comes from proteins in their faecal matter, specifically a protease enzyme called Der p 1. Der p 1 is small enough to penetrate the compromised skin barrier characteristic of eczema, where it activates the immune response that drives inflammation.
Why the bedroom matters most
The average person spends seven to nine hours a night in bed, more time in continuous contact with a single environment than anywhere else. If that environment is high in dust mite allergen, the skin is being exposed for a third of every day.
Dust mites thrive in warm, humid conditions, around 25°C and 75% relative humidity. Bedrooms, particularly in winter when windows are kept closed and heating is on, often provide exactly these conditions.
What actually works
Allergen-impermeable covers for mattresses, pillows, and duvets, with a pore size of 6 microns or less, are the most effective single intervention. Washing bedding at 60°C weekly kills live mites. Lower temperatures don't kill mites reliably.
Replacing feather or down pillows and duvets with synthetic alternatives reduces mite habitat. Vacuuming the mattress with a HEPA-filtered vacuum monthly removes mite matter. A HEPA air purifier in the bedroom reduces airborne allergen particles.
The humidity intervention
Keeping bedroom humidity below 50% makes the environment significantly less hospitable for mites. A hygrometer lets you monitor levels. In humid homes, a dehumidifier in the bedroom is one of the highest-impact environmental interventions available.
Reviewed by the xmahub protocol team. Based on peer-reviewed dermatology literature.