Working in shifts is an industrial and manufacturing concept that has branched out into many other businesses over the past 100 years. Shift work allows a company to maximize its investment in equipment by running that equipment around the clock. Customer service has also widely adopted shift work as it allows a company to be accessible to clients 24 hours a day. It is estimated that close to 15 million workers in the United States alone work in shifts that fall outside of the normal daytime hours. While shift work may seem like the most efficient way to run certain types of businesses, there are some health and safety issues involved that should not be ignored.

Shift work that occurs in the evening or late night hours goes against the normal human circadian rhythms. It is natural for the human body to want to sleep once the sun has gone done, and this can have an effect on the alertness and competency of some workers. It is also more likely for a person to be awake during the day before their night shift than for them to be awake in the early morning hours before a day shift. This can lead to extra fatigue, particularly towards the end of a shift.

Many attempts have been made to understand why workers who have adapted to working at night and sleeping during the day still find themselves falling victim to this increased accident rate. It has been suggested that the need to interact with the regular business and social world during the daylight hours causes some of these workers to adopt a normal daytime schedule on their days off of work. This can disrupt their adjustment to night time shifts. For this reason, it is recommended that the consecutive number of night shifts be limited to 4 in a row, with a maximum of 48 hours of night work per week. Reducing the number of consecutive shifts has been proven to lower accident rates1. Workers should also be given a regular 2 day break from work, and not an extended period of up to a week. Long breaks from work could cause employees to return to a daytime schedule, limiting their ability to adapt to a night shift once it is time to return to work.

Another issue surrounding shift work is the temptation to work two shifts in a row, or work two shifts with only a few hours of break in between. This type of behavior only compounds fatigue, and in the case of certain industrial processes, can put the worker at greater risk for injury. A period of at least 11 hours should be maintained between shifts, and this period should be even longer when workers are being moved from an afternoon shift to an evening shift, and vice versa.

Source: Brogmus G, Maynard W, 2006. Safer Shiftwork Through More Effective Scheduling.