Objectives: Working more (overemployment) or less (underemployment) than preferred has been associated with poor mental health in cross-sectional studies, but longitudinal evidence is scarce. We investigate whether under- and overemployment is associated with 2-year changes of mental health and whether associations vary by job rewards (i.e. high earnings, job security, promotion prospects and occupational prestige).
Methods: We used two waves of the German Socio-Economic Panel (GSOEP), with information on mental health collected in 2006 and 2008. Workers in paid employment (3266 men and 3139 women) who did not change jobs between 2006 and 2008, aged 20-60 years were selected. Under- and overemployment was assessed using the discrepancy between the actual and preferred working hours. Mental health was assessed using the Mental Component Summary (MCS) score, a subscale from the Short Form 12 Health Survey. Questions on rewards at work were added and divided into tertiles. Conditional change models were estimated to predict change in MCS.
Results: Findings indicate that overemployment and low reward at work (for men and women) were linked to a reduction in mental health. Underemployment was not related to a reduction in mental health. Albeit associations between under-/overemployment and mental health slightly differed across levels of reward, interactions did not reach statistical significance.
Conclusions: Our findings demonstrate that overemployment was related to negative mental health change, and that this relationship held true both for people with high and with low reward at work.
Keywords: Conditional change models; Job rewards; Mental health; Overemployment; Socio-economic panel; Underemployment.