WORKERS who toil for 11 or more hours a day are more than twice as likely to suffer depression as those who work nine-to-five, according to a new study.
Researchers tracked thousands of middle aged civil servants for nearly six years and found a major link between overwork and depression.
Now, they are calling for employers to recognise that making staff work too many hours can damage their mental health.
Dr Marianna Virtanen, of the Finnish Institute of Occupational Health and University College London, said the study found a “robust” association between overtime work and depression.
She said: “Although occasionally working overtime may have benefits for the individual and society, it is important to recognise working excessive hours is also associated with an increased risk of major depression.”
According to projections by the World Health Organisation, depressive disorders are expected to become the leading cause of ill-health in high-income countries by 2030.
In addition to the personal toll, mental disorders often affect performance at work and result in time off sick.
The researchers studied 2,000 civil servants in all, and found those who worked 11 or more hours a day were 2.4 times more likely to suffer depression than those who worked seven to eight hours a day.
They said long working hours may affect mental health by creating family conflicts, difficulties in unwinding, and increased stress. It may also affect men and women differently. However, the study found no link between depression and marital status, smoking or the strain of the job.
The authors said their study showed more conclusive evidence of the connection between long working hours and depression. Previous studies looked at people who did one or two hours of overtime a week.
But the team, led by Dr Virtanen, pointed out it has been difficult to compare results across various studies, given that there is no standard cut-off for when overtime starts.
Furthermore, some previous studies included part-time workers, even though people facing health problems often opt for part-time jobs.
The study, published by online journal PLoS One, said: “In conclusion, this suggests an association between long working hours and the onset of a major depressive episode. More studies may be needed to examine whether interventions designed to reduce working hours would alter depression risk in working populations.”
According to figures released this month, some 417,000 workers in Scotland – 19 per cent of the workforce – did unpaid overtime last year, up 20,000 on 2010. The statistics, compiled by the Office for National Statistics, were seized upon by the Trades Union Congress as an example of some employers “exploiting” staff by forcing them to work longer for no extra pay.
Catherine Eadie, health officer at Action on Depression, Scotland’s national charity for depression, said: “This is a paramount issue. We know that flexible working and being able to talk to your manager about any work issues actually creates a more productive team, because they can discuss changes to working patterns, such as dropping the kids off at school and starting later.”