I examined whether working hours have a causal effect on the health behaviors of workers. In assessing the causal relationship, I estimate fixed-effects instrumental variable models by using exogenous variation in adopting a reduced workweek in South Korea as an instrument for work hours. The estimation results reveal that shortening work hours induces individuals to exercise regularly and decreases the likelihood of smoking, with more pronounced effects for heavy smokers. While a work-hour reduction substantially increases the probability of drinking participation, it does not significantly affect the likelihood of frequent or daily drinking habits. In addition, the effect of a work-hour reduction on regular exercise is salient among women and older groups, and the effect on smoking behaviors is more pronounced among men and middle-aged groups.
Working time has long been recognized as strongly linked with the health and well-being of working people, and it has therefore received attention from both researchers and policy makers (Bosch, 1999; Caruso, 2006). For example, long working hours have been shown to be associated with cardiovascular disease, high risk of diabetes, stress and poor mental health, and work-family conflicts (Caruso, 2006; Nakanishi et al., 2001; Sparks et al., 1997; Virtanen et al., 2012).
What are the effects of work hours on the workers' lifestyle habits that affect their health? Long working hours are associated with ill health and unhealthy behaviors such as smoking, heavy alcohol consumption, and lack of physical exercise (Maruyama and Morimoto, 1996; Siegrist and Rodel, 2006; Taris et al., 2011), which are important contributors to largely preventable chronic diseases. Studies have shown that workers compensate for overtime-related job stress by consuming more fatty and sweet foods (Oliver and Wardle, 1999) and that long working hours act as a potential barrier to regular exercise by limiting the time available for nonwork activity (Schneider and Becker, 2005). Furthermore, job stress is supposed to ease stress (Green and Johnson, 1990).
A related strand of research in economics emphasizes the role of unemployment rate, another measure of economic activity, in influencing the health behaviors of individuals. Earlier studies used state-level data to examine the relationship between the local unemployment rates and the drinking and alcohol-related behaviors of workers (Ruhm, 1995; Freeman, 1999). To eliminate the unobserved local economic factors spuriously correlated with health-risk behaviors, these studies used fixed-effects models and found that alcohol consumption and drunk driving increase with economic activity. Several recent studies use individual-level data to exploit the within-person variations in health behaviors; they obtain mixed results. While some researchers find positive relationships between economic activity and alcohol consumption, physical inactivity, and smoking behaviors (Ruhm, 2000, 2005; Ruhm and Black, 2002; Xu and Kaestner, 2010), others find evidence of the counter-cyclicality of drinking (Dee, 2001) or little evidence of the cyclicality of drinking, physical activity, and smoking behaviors (Charles and DeCicca, 2008).
Regarding the most recent economic downturn, using data from the American Time Use Survey, Aguiar et al. (2013) document that the time spent on health care significantly increased during the Great Recession, whereas Teckin et al. (2013) find little association between recent economic deterioration and health behaviors. Asgeisdottir et al. (2012) show that the 2008 economic crisis in Iceland reduced the consumption of alcohol and cigarettes while also reducing the consumption of healthy foods.
Despite considerable evidence linking working time, economic activity, and health-risk behaviors, the causal effects of work hours are still unclear. In the absence of experimental evidence, it is difficult to assess whether workers' health behaviors are affected by working time or whether unobserved third factors such as attitudes toward smoking or drinking influence both working time and health-risk behaviors. Another possibility is reverse causality - that health habits and lifestyle choices influence employment and working time.
The goal of this paper is to investigate whether working hours have causal effects on workers' health behaviors. In assessing the causal relationship, I employ within-individual estimators (or individual fixed-effects (FE) models) to estimate the unobserved factors that yield biased estimates. More importantly, I carry out estimation with fixed-effects models, using exogenous variation in policy adoption as an instrument for work hours. Specifically, I exploit the timing of the implementation of the legislated workweek reduction in South Korea based on establishment size. South Korea experienced a dramatic reduction in working hours during the past decade following the introduction of a 40-h workweek standard, providing a good source of variation in individuals' work time. The 40-h workweek limit was gradually adopted according to establishment size from 2004 to 2011. In order to increase the robustness of the identification strategy in instrumenting work hours, I use the size data for the establishment at which each individual worked the year prior to the initial observation. This fixed-effects instrumental variable (FE-IV) estimator provides consistent results for the causal effects of work hours, addressing both individual heterogeneity and endogenous changes in working time. To the best of my knowledge, this paper is the first to provide evidence for the causal effects of working hours on health behaviors by controlling for both individual fixed factors and time-varying unobservables.
The estimation results suggest that a reduction in work hours lead to individuals' healthier lifestyles. Reducing work hours induces individuals to exercise regularly. A reduction in work hours also decreases the likelihood of smoking, with somewhat more pronounced effects for heavy smokers. While a work-hour reduction substantially increases the probability of drinking participation, it does not affect the likelihood of frequent or daily drinking habits. In addition, the results from a population subgroup analysis indicate that the effect of work-hour reduction on regular exercise is salient among women and older groups and that the effect on smoking behaviors is more pronounced among men and middle-aged groups.
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