Do you have a runny nose even out of the cold and flu season? Or constantly suffer with a cough or itchy and watery eyes?
You may be allergic to the faeces of hundreds of microscopic dust mites living in your pillow, scientists claim.
It's widely known that many of the millions of dead skin cells we shed every day accumulate in our beds.
But if your pillow is two years old, 10 per cent of its weight could be blamed on dust mites and dead skin cells.
As if that wasn't enough enough to make your skin crawl, its the mites poo, not the mites themselves, that people are allergic to, according to The Hygiene Doctor, Lisa Ackerley.
Dr Ackerley said: 'Mites themselves don't carry disease, it is an enzyme in the poo that some people are allergic to.
'If people have asthma, it can make it worse. It can also give you a constant runny nose, itchy eyes, watery eyes and cough.'
Yet, while the symptoms may be unpleasant, mites don't pose any serious health risks.
And, unless you're suffering symptoms, no action needs to be taken, Dr Ackerely said.
'If it is not bothering you then it is fine, but if you are having problems with your health then you should do something,' she added.
'Don't make the bed in the morning because mites like the warmth, so if you pull the sheets back it creates a hostile, cold environment for mites.
'Wash your pillow and then tumble dry it to fluff it up, the heat from the dryer kills them.
'You can even pop the pillow in the freezer to kill the mites – if you have space.'
Avoid drying clothes on radiators because the moisture makes your home more friendly to mites, she advised.
While keeping your house slightly cooler and vacuuming dust up will help to prevent any unwanted illnesses.
Dr Acklerley also told The Sun: 'The cleaner you keep your house the less dust there will be so the less there will be for the mites to eat.
'When you are doing the laundry, you really need to try and put it on a 60 degree wash to kill the dust mites.'