Abstract: The adverse effects of long working hours on health have aroused widespread concern in the society. However, the existing literature has not yet concluded whether the effects take a gradual, discontinuous, or even a phased process. Using 2016 China Family Panel Studies data, this paper applies ordered logit model to analyze effects of working hours on health of different types of workers and uses Shapley decomposition to identify corresponding thresholds. The results indicate that overtime work is quite common in China, especially among manual workers. There are strong associations between working hours and workers' health. With increasing working hours, workers suffer a significant decline in both physical and mental health, and the effect of working hours on health of mental workers is greater than that on health of manual workers. About thresholds of working hours, the results suggest that when the weekly working hours of a mental worker exceed 40 hours, or over 50 hours for a manual worker, their physical health will be significantly worsened. Ｒegardless of workers' type, when they work 70 or more hours weekly, both of their physical and mental health will be significantly damaged.

Keywords: working hours; physical health; mental health; mental workers; manual workers