When do people work? --- Measuring trends in work timing with a Japanese time-use survey ---
Using a Japanese time-use survey, we find a secular increase in the share of workers who work in the late-night and early-morning hours over the past 20 years. This trend remains when controlling for changes in hours worked associated with the business cycle and for changes in demography and the occupational mix. This is a contrast trend seen in the US, where the share of workers working late-night hours declined gradually over time. In addition, the notable increase in the employment rate for evening work (until about 10 pm) was for highly educated, high-income workers, whereas the increase in the employment rate of those working in mid-night, early-morning hours was for workers with low levels of both education and income. We also found differences in employment rate based on day of the week, observing a notable decline in the fraction of highly educated, high-income individuals working on Saturday, but an increase in the employment rate of less educated, low-income workers in the late-night, early morning hours on Saturday. The sustained recession in post-bubble Japan since the early 1990s reduced the number of regular employees working daytime hours, while there was a trend among businesses, particularly in the service industry, to greatly expand operating hours in the hope of sparking at least some demand. There is a possibility that this resulted in the more highly educated, higher income workers working in the desirable daytime hours, while the other workers, having been squeezed out, had no choice but to work at other times. Our results suggest however, that most of those who become to work in undesirable hours are compensated by undesirable time wage premium except for the bottom group who has to work at highest undesirable hours (weekend midnight) without certain wage premium.