While the importance of assessing the occupational consequences of insomnia is emphasized in clinical nosologies and research guidelines, there is little consensus on which aspects of occupational performance should be assessed, the most methodologically justifiable measures of insomnia and work performance, and how outcomes should be reported. The present review was designed to summarize and methodologically critique the assessment of those aspects of occupational performance most impacted by (or most frequently associated with) insomnia symptoms. The 30 studies which met the review inclusion criteria broadly addressed six domains of occupational functioning: absenteeism; workplace accidents; productivity; punctuality; job satisfaction and career progression. Collectively, study outcomes support the conclusions that insomnia symptoms: are consistently associated with excess absenteeism; elevate accident risk in the workplace; reduce subjectively experienced workplace productivity (at least in the shorter term); inhibit career progression; and can degrade job satisfaction. Study outcomes do not support the conclusion that people with insomnia are significantly less punctual than other workers. The overall value of the occupational sleep-health literature, however, is limited by a lack of comparability among studies. In particular, there is a clear need to standardize definitions of sleep and occupational outcomes, and to recognize the confounding influence of health variables on occupational performance and sleep.