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Three hours' extra work a day doubles risk of depression

People who work for 11 or more hours a day are twice as likely to suffer from major depression as those working the standard eight-hour day, research has shown.

More than 2,000 middle-aged civil servants were studied for nearly six years and a robust link was found between regular overtime and depression – even after factoring in risks related to lifestyle, physical health and alcohol. Data from the study has already found that overtime leads to a 60 per cent higher risk of heart disease.

Depression is set to become the leading disease burden in high-income countries such as the UK by 2030, according to the World Health Organisation. Even before the economic crisis, the UK had the longest working hours in Europe. Official figures reveal that more than 40 per cent of lost working days are caused by depression, anxiety and stress.

The study, published in the online journal PLoS ONE, found employees with long working hours were more likely to be men, married or cohabiting and from higher occupational grades than employees with standard working hours.

They also tended to drink alcohol above the recommended limits. After factoring in those differences, people working 11 hours or more were still 2.5 times more likely to have had at least one major depressive episode after six years. None of those in the sample group had previously suffered from any mental health problems.

Marianna Virtanen, of the Finnish Institute of Occupational Health and University College London, and the study's lead author, said: "Although occasionally working overtime may have benefits for the individual and society, it is important to recognise that working excessive hours is also associated with an increased risk of major depression."

Paul Farmer, the chief executive of mental health charity Mind, said: "Making employees work excessive hours is a false economy, as not only are tired, unhappy workers less productive, but they risk developing mental health issues that if handled badly, can be costly to businesses. When people get work-related depression, employers need to move away from seeing this as a sign of weakness, and realise it might also be a sign of something wrong with the workplace."