Underemployment, Overemployment and deterioration of mental health: the role of job rewards

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 two-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 (3,266 men and 3,139 women), who did not change jobs between 2006 and 2008, aged 20-60 years were selected. 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 (7 items) were added and divided into tertiles. Linear regression models were estimated to predict change in MCS.
Results Findings indicate that overemployment (for men and women) is linked to a reduction in mental health, as well as low reward at work. Underemployment is 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 This study is one of the first to shed light on the underlying mechanisms explaining the relation between under-/overemployment and mental health. Our findings demonstrate that overemployment is related to negative mental health change across two years, and that this relationship holds true both for people with high and with low reward at work.