• alertness;
  • napping;
  • productivity;
  • recovery;
  • sleep


Shift work poses a significant threat to multiple aspects of working life. The present review addresses the health, safety/performance, and psychosocial issues associated with shift work. Recent studies have revealed that health disorders due to working in shifts are closely related to dysfunction of sleep and the circadian timing system. Safety and performance problems such as occupational injuries and poor work performance that occur during abnormal working hours can be explained by impaired neurobehavioral function. An increased level of understanding regarding shift work problems as well as sleep and circadian biology should be translated into evidence-based strategies to assist shift workers. Although some promising countermeasures including sleep and circadian approaches have been proposed, many questions regarding better shift schedules and fatigue risk management remain unsolved. In particular, shift work has been defined differently in previous studies, leading to confusion and errors when estimating the associations between shift work and outcomes. Additionally, there are no validated, reliable indicators to represent the adaptability of shift work. Such indicators, if available, could be used for health evaluations of current shift workers and the early detection and treatment of poor adaptation to a given shift schedule. Clearly, modern society exists with individuals who work in shifts. Therefore, effective countermeasures must be developed to reduce the risks arising from shift work. Sleep and circadian biology are expected to direct these processes.