Researchers at ANU say employees who work more than 39 hours a week could be putting their health at risk.
Working more than 39 hours a week could be damaging your health, Australian researchers have found.
A study of more than 7800 Australians has found 39 hours is the "tipping point" when men and women's mental health begins to suffer.
But for working women with other responsibilities such as caring for children and domestic chores, their "tipping point" can come much earlier, at 34 hours.
The healthy limit for men is 47 hours, mainly because they have fewer responsibilities outside the workplace.
Researcher Professor Lyndall Strazdins said the findings show the International Labour Organisation's maximum 48-hour limit for workers set 80 years ago is clearly outdated, largely because it was devised at a time when workplaces were dominated by men.
She said employers, governments and workers all need to start a national conversation about work hours, particularly given the growing expectations in many workplaces for people to work beyond the standard eight-hour day.
"We have a 38-hour working week recommended by Fair Work Australia so the question is now is how do we move towards that and keep our productivity while lowering what has crept in as the expectation for a working week," Prof Strazdins told AAP on Thursday.
"It's a complicated social problem and like most it takes lots of discussion and small steps to make a difference. If we don't do something about it it's probably going to get worse."
The study found men worked an average of 44 hours and spent 21 hours on care and domestic duties a week, while for women it was 33 and 31 hours respectively.
Managers and professionals worked the longest hours, averaging 49 hours a week, and had the highest paid jobs.
Working 48 hours a week was found to be fine for those who had minimal or no caring responsibilities outside of work.
But once those factors were thrown into the mix, people began to feel distress and a deterioration in their mental health after they worked 34.5 hours.
"Our study shows that, in today's labour market, current workhour regulations will not protect women's health or any adult who combines work with significant care-giving," the ANU researchers wrote in their study, published in the journal Social Science & Medicine.
"There is an hour-glass ceiling for those who have care, and if this is not addressed then women will be choosing between working longer hours and compromising their mental health to earn equal income, or working fewer hours than men and entrenching gender inequality."
The findings were based on an analysis of data collected from working men and women aged between 24 and 64 as part of the ongoing Household Income Labour Dynamics of Australia Survey.