You were brought up to make your bed neatly every morning, right?

Well, it’s not the best idea because with all the nighttime sweating (each of us loses around a pint a night, more in the heat of summer) and the warm, moist atmosphere, dust mites will happily breed in their millions. And if you’re wheezy or asthmatic, their faeces could easily trigger a nasty asthma attack.

Much healthier to freeze them out, so pull the covers right back in the morning, open the windows and allow the bed to air.