By ROBIN YAPP, Daily Mail

Last updated at 08:30 18 January 2005

For anyone who can't be bothered to make the bed in the morning - and that includes 99 per cent of all known teenagers - there is welcome news today.

Rather than just being slovenly, you are helping to get rid of dust mites.

Experts warn that the mites, which can cause a host of allergies, thrive in the moist and warm conditions created by a well-made bed with tightly-drawn sheets and blankets. By contrast, a messy bed in which the sheets are simply tossed aside in the morning and left as they fall creates dry conditions which cause the little blighters to dehydrate and die.

1.5million dust mites in your bed

Lead researcher Dr Stephen Pretlove, a building scientist at Kingston University's School of Architecture, said that the average bed could be home to up to 1.5million dust mites.

They can trigger asthma and have also been linked to eczema and a condition called perennial rhinitis, described as being a type of 'year round hayfever'.

"House dust mites feed on scales of human skin so they love to share our beds," said Dr Pretlove. "The allergens they produce are easily inhaled during sleep and are a major cause of illnesses.

"We know that mites can only survive by taking in water from the atmosphere using glands on the outside of their body. Something as simple as leaving a bed unmade during the day can remove moisture from the sheets and mattress so the mites will dehydrate and eventually die."

Dr Pretlove said that conditions for mites are best while we are actually in our beds, thanks to the warmth and moisture we create.

He has teamed up with a team of entomologists and zoologists from London and Cambridge to develop a computer model showing how factors such as ventilation, insulation and heating can influence mite numbers in houses of different shapes and sizes.

Brave volunteers

As the next stage of their project, they have recruited 36 volunteers from around the UK who have had mite populations of varying sizes introduced into their homes so that researchers can monitor how they respond to different environmental conditions.

The mites are placed in tea-bag like 'pockets' which allow them to experience the warmth and moisture of the environment without being able to escape.

Dr Pretlove said the findings could help create healthy homes and reduce the cost to the NHS of treating allergies, which now tops £1billion a year.