
A team led by Maria Virtanen from the Finnish Institute of Occupational Health and University College London investigated the work hours of the civil servants who had no psychological problems. Subsequently, they were checked again after 5 years to see if they had suffered from depression.
It appeared that civil servants who work 11 hours or more per day, are more than twice as likely to suffer from a serious depression than their colleagues who worked between 7 and 8 hours. The researchers dare not say how come that people who work longer are easier to be depression.