Working paper title: Sleepless Nights, Safer Roads? Night-time Air Alerts and Behavioral Risk Avoidance

By: Dariia Mykhailyshyna

This paper estimates the effect of night-time air alert exposure on next-day traffic accidents using daily administrative data from Lviv, Ukraine, over 2022-2024. Air alerts signal genuine aerial threats, bundling sleep disruption with exposure to acute danger and creating competing channels: fatigue impairment versus threat-induced risk aversion. Exploiting variation in alert timing that is unanticipated by local residents, I find that each additional hour of night alert reduces full-day accidents by 10 percent, with effects concentrated in the afternoon and evening. These reductions are driven by behavioral risk avoidance on two margins: fewer discretionary trips and lower conditional accident risk. Accident cause analysis shows that fatigue-sensitive causes are unchanged while risky-behavior causes decline significantly - the opposite of what the fatigue hypothesis predicts. The risk avoidance response was strongest in 2022 and attenuated in subsequent years, consistent with adaptation to recurring war threats.

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