Despite the ongoing public debate about precarious working conditions in academia, there is only little evidence on working hours and overtime work for the group of (non-tenured) junior academics. We make use of unique longitudinal survey data on the occupational situation and careers of doctoral students and doctorate holders in science, technology, engineering and mathematics fields in Germany. We find that overtime hours are less pronounced among firm employees holding a doctorate and among postdocs than they are among doctoral students. This result is prevalent both between individuals in the cross-section and with regard to individual fixed effects panel estimations. In contrast to firm employees, overtime hours are in a considerable way positively associated with part-time contracts for doctoral students. Furthermore, our results reveal that individuals’ career orientation is positively associated with extra hours. In contrast, individuals with family responsibilities spend significantly fewer hours at work.