Losing Sleep at the Market: The Daylight-Savings Anomaly

We explore the connection between equity returns and sleep disruptions following daylight-savings time changes. In international markets, the average Friday-to-Monday return on daylight-savings weekends is markedly lower than expected, with a magnitude 200 to 500 percent larger than the average negative return for other weekends of the year. This ``daylight-savings anomaly'' in financial markets is consistent with desynchronosis research which has identified the effects of changes in sleep patterns on judgment, anxiety, reaction time, problem solving and accidents. This paper suggests sleep effects of daylight-savings time changes may be impacting market participants internationally.