Saved by the bell: does working too much increase the likelihood of depression?

Depression is a serious public health concern that has been predicted to be the leading cause of the burden of disease in high-income countries by 2030 [1]. In addition to human suffering, depression affects families and communities and is associated with substantial work impairment, lost work days and reduced productivity. Negative life events have long been a major focus of research on psychosocial risk factors for depression. Life events that possess a high degree of threat, negative emotions and experience of loss have been found to precede the onset of depression (for a review, see Hammen [2]). The hypothesized underlying pathways involve dysregulation of the physiological stress system. The hypothalamic–pituitary– adrenal axis is activated during psychological stress and involves secretion of corticotropin-releasing hormone and cortisol, the hormonal end point of the hypothalamic– pituitary–adrenal activation. Both corticotropin-releasing hormone and cortisol levels have been shown to be elevated in depressed people [3]. Given the link between the stress systems and depression, it is plausible to assume that not only acute stress related to negative life events, but also more chronic psychological stress may be of etiological importance in the development of depression [4]. Recently, an increasing research interest has been focused on possible work-related stress exposures, such as long working hours and mental health. Several issues support the idea that extensive working might be depressogenic. First, employees working long hours are likely to have reduced time available for sleep and recovery from work, potentially leading to chronic fatigue, poor health-related behaviours and, eventually, deterioration in health [5,6]. Second, they may also be exposed for longer periods of time to psychosocial and physical workplace hazards, such as high demands (which can also be an underlying cause of extended working hours) and other poor working conditions, as compared with those working shorter days [6]. Third, prospective cohort studies and case–control studies have linked long working hours to an increased risk of stress-related chronic diseases, such as coronary heart disease [5]. Evidence regarding the association between long working hours and mental health is accumulating, but is not without limitations. To date, more than 20 crosssectional studies using individual-level data have been published on the effects of long working hours on mental health, for example, looking at symptoms or depression. Of them, slightly more than half failed to find any association, while the rest of them reported a positive association. None of the studies found a negative association (i.e., long working hours being a protective factor for mental health). The problem in cross-sectional studies is their inability to prove the direction of the association. Employees with mental health symptoms may either shorten or lengthen their working hours depending on the circumstances, and the association found can Expert Rev. Neurother. 12(5), 497–499 (2012)

[1]  M. Jokela,et al.  Long Working Hours and Coronary Heart Disease: A Systematic Review and Meta-Analysis , 2012, American journal of epidemiology.

[2]  J. Bonde,et al.  With long hours of work, might depression then lurk? A nationwide prospective follow-up study among Danish senior medical consultants. , 2012, Scandinavian journal of work, environment & health.

[3]  M. Kivimäki,et al.  Overtime Work as a Predictor of Major Depressive Episode: A 5-Year Follow-Up of the Whitehall II Study , 2012, PloS one.

[4]  M. Marmot,et al.  Long working hours and symptoms of anxiety and depression: a 5-year follow-up of the Whitehall II study , 2011, Psychological Medicine.

[5]  N. Jansen,et al.  Changes in mental health as a predictor of changes in working time arrangements and occupational mobility: results from a prospective cohort study. , 2009, Journal of psychosomatic research.

[6]  David Gimeno,et al.  Long working hours and cognitive function: the Whitehall II Study. , 2008, American journal of epidemiology.

[7]  N. Jansen,et al.  Health effects of transitions in work schedule, workhours and overtime in a prospective cohort study. , 2007, Scandinavian journal of work, environment & health.

[8]  William B Bunn,et al.  Do Long Workhours Impact Health, Safety, and Productivity at a Heavy Manufacturer? , 2007, Journal of occupational and environmental medicine.

[9]  R. Rosa,et al.  Long working hours, safety, and health: toward a National Research Agenda. , 2006, American journal of industrial medicine.

[10]  C. Mathers,et al.  Projections of Global Mortality and Burden of Disease from 2002 to 2030 , 2006, PLoS medicine.

[11]  T. Åkerstedt,et al.  Overtime work and its effects on sleep, sleepiness, cortisol and blood pressure in an experimental field study. , 2006, Scandinavian journal of work, environment & health.

[12]  D. Swaab,et al.  The stress system in the human brain in depression and neurodegeneration , 2005, Ageing Research Reviews.

[13]  C. Hammen Stress and depression. , 2005, Annual review of clinical psychology.

[14]  T. Kido,et al.  A follow-up study on the association of working conditions and lifestyles with the development of (perceived) mental symptoms in workers of a telecommunication enterprise. , 2003, Occupational medicine.

[15]  C. Bildt,et al.  Psychosocial conditions on and off the job and psychological ill health: depressive symptoms, impaired psychological wellbeing, heavy consumption of alcohol , 2003, Occupational and environmental medicine.

[16]  A. Hagihara,et al.  A prospective observation of onsets of health defects associated with working hours. , 2003, Industrial health.

[17]  C. Bildt,et al.  Gender differences in the effects from working conditions on mental health: a 4-year follow-up , 2002, International archives of occupational and environmental health.

[18]  C. Tennant Work-related stress and depressive disorders. , 2001, Journal of psychosomatic research.

[19]  M. Shields,et al.  Long working hours and health. , 1999, Health reports.

[20]  Andrew Steptoe,et al.  A longitudinal study of work load and variations in psychological well-being, cortisol, smoking, and alcohol consumption , 1998, Annals of behavioral medicine : a publication of the Society of Behavioral Medicine.