How often should your bras, pyjamas and sheets be washed? The Daily Mail consulted a microbiologist, underwear specialist and clothing designers on how often you really need to clean everything.

BRAS – after two wears

It doesn’t sound like much, but Kelly Dunmore, lingerie expert for Rigby & Peller, is adamant. ‘The crease in your bust and the area under your arms are hot, sweaty environments. Cleaning after every two wears, possibly three, is ideal,’ she says.

Avoid machine washing, as activity in the drum will ruin elasticity and shorten its useable life (which should be at least 12 months).

Handwash instead, then let the bra drip dry at room temperature, as heat from a radiator or tumble dryer destroys Lycra.

PYJAMAS - after two wears

‘Close fitting pyjama bottoms or shorts need to be washed after two wears. Tops might last a little longer,’ says Kelly. ‘It’s important to keep fresh and clean, especially in bed.

‘Sleeping with a hot water bottle in winter and thick pyjamas will only make you sweat more,’ says Kelly. You can buy copper pyjamas designed to be worn for a week or more (in hospitals or care homes). These are made using 60 per cent copper infused yarn with anti-microbial, antibacterial properties.

SHEETS - once a week

We shed millions of skin cells every day, many of them in bed, and lose a litre of sweat in a typical night. Both attract dust mites that feed on it.

Mites, though harmless, produce droppings containing allergens that can trigger itching eyes, rhinitis (inflammation of the nose) and asthma. Worryingly, one in ten of us wash our sheets only every four weeks, and more than a third wait 14 days, according to a recent YouGov poll.

Experts recommends washing them once a week at a minimum of 60c to destroy bacteria.