The National Institute for Occupational Safety and Health
Research indicates that shift work and long work hours increase health and safety risks by disturbing sleep and circadian rhythms and reducing time for family and non-work responsibilities. Long work hours, in addition, increase exposures to hazards at work and reduce recovery times. These immediate effects promote stress, fatigue, negative mood, discomfort, physiologic dysfunction, and poor health behaviors (overeating, smoking, and lack of exercise). These in turn could lead to illnesses and injuries for the worker. In addition, the risks can extend to families, for example, from the conflicting demands of work and family.
Risks to employers include reduced productivity and increases in nursing care errors, which negatively affect patients. Mistakes by fatigued nurses can have broad-reaching negative effects on the community, ranging from nursing care errors to motor vehicle crashes during the commute. Scientific evidence indicates that the characteristics of the worker and the demands of the job influence whether these negative outcomes occur.
Source: The National Institute for Occupational Safety and Health