Shift work occurs in a company that operates 24 hours per day and relies on multiple shifts of workers to fill roles and complete tasks. In some cases, shift work means a person works outside of the traditional 9:00 a.m. to 5:00 p.m. structure.
In some companies, shift work means three distinct eight-hour shifts. In other cases, companies have two 12-hour shifts. Shift work is common in retail, fire and police departments, manufacturing, and health care. People who work evening or overnight sometimes struggle with sleep patterns. A particular sleep disorder related to the effects of shift work is called shift work disorder.