MEN are less stressed if their wives earn less than they do.

A recent study by the University of Bath has revealed that men are least stressed when their wives earn up to 40% of the household salary.

However, they tend to be uneasy if their partner's wages become more than 40%.

The study of over 6,000 American heterosexual couples over 15 years showed husbands are most anxious when they are the sole breadwinner, shouldering all the burden of responsibility for the household's finances.

Stress levels decline as their wives' earnings approach 40% of household income.

But as women's earnings go through that point, the study showed husbands' stress levels gradually increasing.

Dr. Joanna Syrda, an economist at the University of Bath's School of Management said these findings suggest that social norms about male breadwinning—and traditional conventions about men earning more than their wives can be dangerous for men's health.

"This is a large study but of a specific group other convention apply in other groups and societies and the results may change as times move on. However, the results are strong enough to point to the persistence of gender identity norms, and to their part in male mental health issues.

“Persistent distress can lead to many adverse health problems, including physical illness, and mental, emotional and social problems," she said.

Dr. Syrda noted the study also showed that husbands did not suffer psychological distress about their wives' income if their wife was the higher earner before marriage and the existing and potential income gap was clear to them.

Figures from the Pew Research Centre in the US show only 13% of married women earned more than their husbands in 1980.

But by 2017 the figure was close to one third and the trend was likely to continue.

Dr. Syrda said she and other researchers were increasingly interested in how this would affect social norms, wellbeing, and our understanding of masculinity.