Despite the well-known negative correlation between long working hours and workers’ health, credible causal evidence for the short- and particularly long-run is scarce.
We study a nationwide policy trial from Sweden in 1920 that reduced the standard workweek from 55 to 48 hours--but only for selected occupations--while keeping earnings constant. Using full population data and difference-in-differences designs, we demonstrate that reduced working hours led to a 15% decline in annual mortality rates over the first six years, driven by fewer workplace accidents, serious injury at work, and deaths from heart disease. Causal forest estimators indicate particularly strong effects for older workers. Long-run effects were substantial: affected workers lived up to one year longer over the next 50 years.
Our results suggest that reducing working hours, particularly in labour-intensive occupations, could yield large and lasting health benefits globally.
