Regular overtime significantly increases risk of life-threatening illnesses for females
Over 60 hours a week for over three decades appears to triple the risk of diabetes, cancer, heart trouble and arthritis
Women who do a lot of overtime over their career are at greater risk of life-threatening illnesses, including heart disease and cancer.
Working over 60 hours a week for over three decades appears to triple the risk of diabetes, cancer, heart trouble and arthritis for women.
The risk begins to climb when women put in more than 40 hours and takes a decidedly bad turn above 50 hours, Ohio State University researchers found.
But men fare better with a tough work schedule because they do not have to juggle work and family responsibilities and so are less stressed and discontented, it was suggested.
They only had a higher risk of arthritis.
Professor Allard Dembe said: "Women - especially women who have to juggle multiple roles - feel the effects of intensive work experiences and that can set the table for a variety of illnesses and disability.
"People don't think that much about how their early work experiences affect them down the road
"Women in their 20s, 30s and 40s are setting themselves up for problems later in life."
The study analysed the interviews with almost 7,500 people who were part of the National Longitudinal Survey of Youth.
They then compared cases of serious illnesses and hours worked over a 32-year period.
Previous research found workers who put in long hours face more stress, have more sleep and digestive trouble and are more fatigued.
Their performance also dips and are more accident prone.
The survey gave researchers long-term data of participants who were at least 40 in 1998 who were asked about their health and chronic conditions.
They averaged the self-reported hours worked each week over 32 years and compared the hours worked to the incidence of eight chronic diseases.
These were heart disease, cancer (except skin cancer), arthritis or rheumatism, diabetes or high blood sugar, chronic lung disease including bronchitis or emphysema, asthma, depression and high blood pressure.
A minority of the full-time workers put in 40 hours or fewer per week, over half (56 per cent) worked an average of 41 to 50 hours, an eighth (13 per cent) worked an average of 51 to 60 hours, and 3 per cent averaged more than 60 hours.
Prof Dembe found a clear and strong relationship between long hours and heart disease, cancer, arthritis and diabetes in women.
Men who worked long hours had a higher incidence of arthritis, but none of the other chronic diseases.
And those men who worked moderately long hours of between 41 to 50 hours weekly had lower risk of heart disease, lung disease and depression than those who worked 40 hours or fewer.
As the data addresses chronic diseases reported by age 40 or 50, it identifies early-onset disease and doesn't shed light on the possible associations between long hours and lifetime risks, which could prove even more profound.
He added: "The early onset and identification of chronic diseases may not only reduce individuals' life expectancy and quality of life, but also increase health care costs in the long term."
And it does not draw a distinction between those who choose to put in the extra hours and those forced to for the money or work culture.
Prof Dembe said: "It could make a difference.
"You might still be working hard, but the fact that it's your choice might help you stay healthier."
The study was published in the Journal of Occupational and Environmental Medicine.