a1 Finnish Institute of Occupational Health, Helsinki, Finland
a2 Department of Epidemiology and Public Health, University College London, UK
a3 INSERM U1018, France
a4 Centre de Gérontologie, Hôpital Ste Périne, AP-HP, Paris, France
a5 Centre for Psychiatry, Wolfson Institute of Preventive Medicine, Queen Mary's School of Medicine and Dentistry, London, UK
a6 Department of Public Health, University of Turku, Finland
a7 Turku University Hospital, Finland
Background Although long working hours are common in working populations, little is known about the effect of long working hours on mental health.
Method We examined the association between long working hours and the onset of depressive and anxiety symptoms in middle-aged employees. Participants were 2960 full-time employees aged 44 to 66 years (2248 men, 712 women) from the prospective Whitehall II cohort study of British civil servants. Working hours, anxiety and depressive symptoms, and covariates were measured at baseline (1997–1999) followed by two subsequent measurements of depressive and anxiety symptoms (2001 and 2002–2004).
Results In a prospective analysis of participants with no depressive (n=2549) or anxiety symptoms (n=2618) at baseline, Cox proportional hazard analysis adjusted for baseline covariates showed a 1.66-fold [95% confidence interval (CI) 1.06–2.61] risk of depressive symptoms and a 1.74-fold (95% CI 1.15–2.61) risk of anxiety symptoms among employees working more than 55 h/week compared with employees working 35–40 h/week. Sex-stratified analysis showed an excess risk of depression and anxiety associated with long working hours among women [hazard ratios (HRs) 2.67 (95% CI 1.07–6.68) and 2.84 (95% CI 1.27–6.34) respectively] but not men [1.30 (0.77–2.19) and 1.43 (0.89–2.30)].
Conclusions Working long hours is a risk factor for the development of depressive and anxiety symptoms in women.
(Received February 16 2010)
(Revised August 18 2010)
(Accepted January 13 2011)
(Online publication February 18 2011)