Can't see the dust mites? Click here to watch the film.
In the latest of his Sleep Watch films Michael Mosley met Rob - he often struggles to get to sleep because his asthma flares up when he goes to bed.
When expert Gary Farron takes a sample from Rob's bed it reveals flakes of dead skin.
Look closer at the flakes and they're seen to contain dust mites. Five thousand could fit on the head of a pin. Each of us shares our bed with approximately 2.5million dust mites. For asthma sufferers this can be a serious problem as dust mite excrement can trigger inflammatory responses.
So, how to reduce dust mites? Here are some tips:
• Use complete barrier covering systems on your mattress, duvet and pillow.
• Remove all carpets and replace with hard flooring.
• Vacuum all areas frequently. Use a vacuum cleaner that has good suction and a filtered exhaust that does not scatter dust. Damp dust all surfaces or use an attachment on your vacuum cleaner. Be sure to vacuum your curtains.
• Remove all soft toys from beds. Put them into a bag in the freezer for a minimum of six hours every one to two weeks to kill house-dust mites.
• Hot wash (at 60 degrees C) sheets, duvet covers and pillowcases once a week. Although some people are allergic to feathers, there is no conclusive evidence to show that synthetic, 'hypo-allergenic' pillows are any better.
• Clean your soft furnishings with anti-house-dust mite chemicals.
• Use a dehumidifier to dry the air, as this makes it more difficult for the house-dust mites to survive.
Do you have dust mite banishing tips? Are dust mites a problem in your household?