Blonde women are dyeing their hair brown – to be taken more seriously in the office.

One in three female employees with light-coloured hair have followed in the footsteps of Scarlett Johansson and Black Eyed Peas singer Fergie by adopting a more sober shade.

The trend comes at a time when companies the length and breadth of Britain are laying off staff amid the deepening recession.

One in three female employees with light-coloured hair have followed in the footsteps of Scarlett Johansson, pictured,  by adopting a more sober shade

Researchers also found 62 per cent of people think brunettes look more professional than blondes in the workplace.

Dan Hadley of Superdrug, which commissioned the study, said: ‘The current economic climate is obviously making women take more care with their appearance at work, even down to their hair colour.

‘The study shows brunettes do seem to be taken more seriously in the work place which is causing a rise in fair headed women darkening their locks.

‘It’s incredible how changing your hair colour can alter people’s perception of you as well as making you feel more confident too.’

A large percentage of fair-haired women believe their hair colour has held them back in their career in the past

The study revealed 31 per cent of blonde women have gone brunette to appear more intelligent in the office.

It also emerged 38 per cent of fair-haired women believe their hair colour has held them back in their career in the past.

And those who have changed hair colour reckon it has paid off with 38 per cent believing they have been taken more seriously by their boss.

The survey of 2,500 women also revealed that almost a quarter have even been given a promotion.

And it’s not just our careers that are affected by hair colour. it can also affects a woman’s sex life.

Researchers found red heads have the most sex – enjoying a romp three times a week, compared to twice a week for brunettes.

Blondes emerged as the most adventurous in the bedroom, with a quarter saying they are open to trying new things and one in five having had sex in a field.

One in twenty even admitted to having sex on a train.

The poll also revealed that those with fair hair are most likely to have a one-night stand after 65 per cent of blondes admitted to sleeping with someone and not seeing them again.

Brunettes are least likely to have a one-off fling though with less than half saying they’ve had one.

And those with black hair are most likely to be unfaithful in a relationship with 44 per cent owning up to having an affair, compared to just 33 per cent of blondes.