'When you get out of bed, fold it back for 30 to 60 minutes to air, then you're not trapping any moisture in the bed.
But if it's just you and you shower before bed, wear pyjamas, don't use hair products and don't have pets, you can get away with every fortnight or so.
Some experts recommend washing bed linen daily when ill, while others say every three days is fine (unless they're clearly dirty).
'Animals will bring in dirt from outside, and while that won't necessarily make you ill, it adds to the smell of bedding,' says Lisa.
Heidi recommends not making your bed straight away and allowing it to air for 30 minutes to avoid trapping moisture under the sheets.
