We conducted 3 studies to investigate how poor quality sleep relates to work injuries. First, using a sample of employed people living in the United Kingdom (N = 4,238; Study 1), we found that poor quality sleep was related to more frequent workplace injuries via negative affect rather than cognitive failures. Second, we again compared parallel pathways using a sample of USA employees (N = 202; Study 2): poor quality sleep was related to more frequent work injuries via work-related negative affect but not work-related cognitive failures. Third, we used a 2-wave sample of employees from the United Kingdom (N = 71; Study 3) finding that poor quality sleep was related to more frequent work injuries 7 weeks later via negative affect. Comparing high arousal and low arousal negative affect as competing pathways showed that there was a significant indirect effect of the former on the poor quality sleep-work injuries relationship but not the latter. Across 3 studies, we implicated the role of self-control failure stemming from poor quality sleep in predicting more frequent work injuries and suggested initiatives targeting high arousal negative affect as a way of reducing work injuries.