Sunset Time and the Economic Effects of Social Jetlag: Evidence from US Time Zone Borders

The rapid evolution into a 24h society challenges individuals’ ability to conciliate workschedules and biological needs. Epidemiological research suggests that social and biologicaltime are increasingly drifting apart (“social jetlag†). This study uses a spatial regressiondiscontinuity design to estimate the economic cost of the misalignment between social andbiological rhythms arising at the border of a time-zone in the presence of relatively rigid socialschedules (e.g., work and school schedules). Exploiting the discontinuity in the timing of naturallight at a time-zone boundary, we find that an extra hour of natural light in the eveningreduces sleep duration by an average of 19 minutes and increases the likelihood of reportinginsufficient sleep. Using data drawn from the Center for Disease Control and Preventionand the US Census, we find that the discontinuity in the timing of natural light has significanteffects on health outcomes typically associated with circadian rhythms disruptions (e.g.,obesity, diabetes, cardiovascular diseases, and breast cancer) and economic performance (percapita income). We provide a lower bound estimate of the health care costs and productivitylosses associated with these effects.