The authors examine the differential influence of time changes associated with Daylight Saving Time on sleep quantity and associated workplace injuries. In Study 1, the authors used a National Institute for Occupational Safety and Health database of mining injuries for the years 1983–2006, and they found that in comparison with other days, on Mondays directly following the switch to Daylight Saving Time—in which 1 hr is lost—workers sustain more workplace injuries and injuries of greater severity. In Study 2, the authors used a Bureau of Labor Statistics database of time use for the years 2003–2006, and they found indirect evidence for the mediating role of sleep in the Daylight Saving Time–injuries relationship, showing that on Mondays directly following the switch to Daylight Saving Time, workers sleep on average 40 min less than on other days. On Mondays directly following the switch to Standard Time— in which 1 hr is gained—there are no significant differences in sleep, injury quantity, or injury severity.

Workplace injuries have long been an important topic in the management and applied psychology literatures (for a recent review, see Clarke, 2006). Workplace injuries can lead to a host of problems for organizations, including lost productivity, legal action, turnover, and lost human capital. Workplace injuries also lower the quality of life of employees, may result in lost income, and in extreme cases can result in death. The National Safety Council (2008) reported that there were 3.7 million disabling work injuries and 4,988 work fatalities in the United States in the year 2006, with an estimated cost to businesses of $164.7 billion. Researchers have examined many antecedents of workplace injuries, including organizational climate (Hofmann & Stetzer, 1996; Zohar, 1980