The sad reason so many successful women dye their hair brown.

When it comes to tips for getting ahead in the workplace, the most obvious might be to work hard, take initiative, always arrive on time and network.

But according to one female CEO, the secret might actually lie in the colour of your hair.

Eileen Carey, CEO of Glassbreakers, a diversity and inclusion enterprise software company, believes dyeing her blonde hair brown helped her in the workforce.

"When I first started my company and I was fundraising, I was given advice from a friend who just broke down in plain and simple terms perception and how I would be perceived," she recently told ABC News.

"I made the decision, based on research, to change my perception so that it improved the likelihood of being taken more seriously as a leader, as opposed to maybe as a sexual object."

The 31 year old told the BBC that being a brunette makes her "look older and I needed that, I felt, in order to be taken seriously."

She says in the tech industry, where sexism is still rife, it was a necessary change.

"I want to be seen as a business leader and not as a sexual object. Those lines are still crossed very often in this space," she said.

The stereotype of a "dumb blonde" may be a cliche, but it's a perception that appears to persist.

In his book Body Language: The Signals You Don't Know You're Sending And How to Master Them, Visiting Professor of Psychology at Gresham College, London, Glenn Wilson says brunettes tend to be taken more seriously and for that reason "may be preferred as long-term partners or business associates."

A 2010 British study of 2,500 women found that 62 per cent of workers believed brunettes looked more professional in the workplace than blondes.

The study, commissioned by beauty and health retailer Superdrug, discovered that 31 per cent of blonde women had dyed their hair darker to appear more intelligent in the office while 38 per cent of women with naturally lighter hair believed their hair colour had at some point held them back in their career.

The same number believed they had been taken more seriously by their boss following the colour change.

The discrimination also extends to wage discrepancy.

Australian economic lecturer Dr Geni Dechter looked into hair colour and salary in 2009 when she was working in the US and found hair colour had a "significant" impact on entry level wages for young women, but not young men.

Non blondes with higher education earned nine per cent more than blondes with the same level of education.

Interestingly, she identified that it was not just due to employers having lower expectations about blonde women's productivity or ability compared to their darker haired colleagues.

Listen: Janine Allis on how to get a pay increase. Post continues after audio.

"Maybe it's a more complex preference structure - for some reason some employers don’t like blondes," she said.

In slightly better news, she found that the wage gap closed after about five years - presumably after blondes were able to demonstrate their hair colour had nothing to do with their competence. Imagine that!

Fortunately it looks like in Australia at least, if you are a natural blonde, you might not have to speed dial your hairdresser straight away.

While there are still more CEOs named John than there are female CEOs in Australia, of the eight female CEOs in the 200 largest ASX-listed companies, only one has dark brown hair; Genworth Mortgage Insurance Australia's Georgette Nicholas.

Of the remaining seven, five are blonde and two on the lighter shade of brown/bronde.

The data that women are still way behind in the workplace is overwhelming, but I have a sneaking suspicion the problem is far bigger and more complex than the colour the hair sprouting out our heads happens to be.

Have you ever felt discriminated on based on your hair colour?

The award-winning podcast Mamamia Out Loud is doing their first live show. There will be laughs, disagreements and you can meet the hosts afterwards! We’re also donating $5 of every ticket price to Share The Dignity so grab your friends and come along to share the love and laughs, get your tickets here.

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