SHIFT WORK

Shift work is an employment practice designed to make use of the 24 hours of the clock, rather than a standard working day.

The term shift work includes both long-term night shifts and work schedules in which employees change or rotate shifts.

A related yet different concept, the work shift, is the time period during which a person is at work.

A day may be divided into three shifts, each of eight hours, and each employee works just one of those shifts; they might for example be 00:00 to 08:00, 08:00 to 16:00, 16:00 to 24:00; times are given in the 24-hour clock.

Generally, "first shift" refers to the day shift, with "second shift" running from late afternoon to midnight or so, and "third shift" being the night shift.

On occasion, more complex schedules are used, sometimes involving employees changing shifts, in order to operate during weekends as well, in which case there will be four or more sets of employees.

Twelve-hour work shifts are also in use. In a modern steelworks, four sets of personnel are used, working consecutive days in one twelve hour shift (06:00-18:00 and vice-versa).

Shift A will work days, and shift B nights, over a 48-hour period, before handing over to shifts C and D and taking 48 hours off.

In the offshore petroleum industry, employees may work 14 consecutive days or nights, 06:00-18:00 or 18:00-06:00, followed by three or four weeks free.

Shift work was once characteristic primarily of manufacturing industry, where it has a clear effect of increasing the use that can be made of capital equipment and allows for up to three times the production compared to just a day shift.

The use of shift work in manufacturing varies greatly from country to country.

Shift work has been traditional in the armed forces: for example sailors must be available to handle a vessel around the clock, and a system of naval watches organised to ensure enough hands are on duty at any time.

Service industries now increasingly operate on some shift system; for example a restaurant or convenience store will normally each day be open for much longer than a working day.

Shift work is also the norm in governmental and private employment in fields related to public safety and healthcare, such as police, fire prevention, security, emergency medical transportation and hospitals.

Companies working in the field of meteorology, such as the National Weather Service and private forecasting companies, also utilize shift work, as constant monitoring of the weather is necessary.

The swing shift, also known as "second shift", is scheduled during the afternoon and evening, such as 4 p.m. to midnight or 3 p.m. to 10 p.m. in the United States.

According to John Frehse of the labor management firm Core Practice Partners, the swing shift is the least desirable of the three possibilities.

The swing shift in the offshore petroleum industry in Norway refers to a two week tour where one works 12-hour days the first seven days and 12-hour nights the second, or vice versa.

The graveyard shift means a shift of work running through the early hours of the morning, especially one from midnight until 8 am.

There is no certainty as to the origin of the phrase night shift; according to Michael Quinion it is little more than "an evocative term for the night shift.

The February 15, 2005 issue of American Family Physician noted that shift work has been associated with cluster headaches.

A study by Knutsson et al in 1986 found that shift workers who had worked in that method for 15 years or more were 300% more likely to develop ischaemic heart disease.

In 1987, working the night shift first became associated with higher rates of cancer.