Energy Institute at Haas

Standardized clock time is perhaps the most ubiquitous behavioral nudge on the planet. It helps schedule and coordinate economic behavior, but also creates tension when it shifts activities away from their locally optimal solar time. Debates about daylight saving time and areas switching time zones center on this tension. We directly measure the clock- vs. solar-time tradeoff using geolocated data on online behavior (Twitter), commute times (Census), and foot traffic (SafeGraph). A one-hour change in the wedge between solar time and clock time shifts behavior 10–32 minutes, with larger effects in northern latitudes and for activities occurring closer to sunrise.