Shift work

For other uses, see Shift work (disambiguation).

"Second shift" redirects here. For the concept in sociology, see double burden.

Shift work is an employment practice designed to make use of or provide service for respectively the 24 hours of the clock per each day of the week (abbreviated as 24/7).

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.

Health consequences

Main article: Shift work sleep disorder

The February 15, 2005 issue of American Family Physician noted that shift work has been associated with cluster headaches. Health problems in the short term can also include fatigue, stress and loss of concentration, a higher rate of absence from the job and poor sexual performance, as shown in the majority of 200 variable-shift workers in a recent study in Kuwait.

Long term consequences of disturbing natural circadian rhythms have been investigated also. A study by Knutsson et al. in 1986 found that shift workers who had worked in that method for 15 years or more were three times more likely to develop ischemic heart disease.

In 1978 Cohen et al. proposed that reduced production of the hormone melatonin might increase the risk of breast cancer, citing "environmental lighting" as a possible causal factor. Working the night shift first became associated with higher rates of cancer in 1987. This may be due to alterations in circadian rhythm: melatonin, a known tumor suppressant, is generally produced at night and late shifts may disrupt its production. Multiple studies have documented a link between night shift work and the increased incidence of breast cancer.

The WHO's International Agency for Research on Cancer listed "shiftwork that involves circadian disruption" as a probable carcinogen in 2007 (IARC Press release No. 180).

UCSF neurologist Louis Ptacek, who studies circadian rhythms, genes and sleep behaviors, has been quoted: "It's not surprising, we have evolved on a planet that is rotating every 24 hours. Our internal clock is more than just when we sleep and wake. It's related to cell division and it regulates our immune systems. When we battle our internal clock, that has complications."

A good review of current knowledge of the health consequences of exposure to artificial light at night and an explanation of the causal mechanisms was published in the Journal of Pineal Research in 2007.

One study suggests that, for those working a night shift (such as 23:00 to 07:00), it may be advantageous to sleep in the evening (14:00 to 22:00) rather than the morning (08:00 to 16:00). The study's evening sleep subjects had 37% fewer episodes of attentional impairment than the morning sleepers.

The health consequences of shift work may depend on one's chronotype, that is, whether one is a day person or a night person, and what shift one is assigned to.

Cognitive Effects of Shift work

There are four major determinants of cognitive performance and alertness in healthy shift-workers. They are: circadian phase, acute sleep deprivation, chronic sleep deficit, and sleep inertia.

The circadian phase is relatively fixed in humans; attempting to shift it so that an individual is alert during the circadian bathyphase is difficult. Sleep during the day is shorter and less consolidated than night-time sleep.

Acute sleep deprivation occurs during long shifts with no breaks, as well as during night shifts when the worker sleeps in the morning and is awake during the afternoon, prior to the work shift. A night shift worker with poor daytime sleep may be awake for more than 18 hours by the end of his shift. The effects of acute sleep deprivation can be compared to impairment due to alcohol intoxication, with 19 hours of wakefulness corresponding to a BAC of 0.05%, and 24 hours of wakefulness corresponding to a BAC of 0.10%. Much of the effect of acute sleep deprivation can be countered by napping, with longer naps giving more benefit than shorter naps. Some industries, specifically the Fire Service, have traditionally allowed workers to sleep while on duty, between calls for service. In one study of EMS providers, 24 hour shifts were not associated with a higher frequency of negative safety outcomes when compared to shorter shifts.

Chronic sleep deficit occurs when a worker sleeps for fewer hours than is necessary over multiple days or weeks. The loss of two hours of nightly sleep for a week causes an impairment similar to those seen after 24 hours of wakefulness. After two weeks of such deficit, the lapses in performance are similar to those seen after 48 hours of continual wakefulness. The number of shifts worked in a month by EMS providers was positively correlated with the frequency of reported errors and adverse events. A study conducted by Defense Research & Development Canada found that "with respect to sustaining cognitive performance in the face of nocturnal alarms, clearly schedule 4 [24/72] is the best schedule and schedule 5 [another schedule with 24 hour shifts] is the second best." The study also compared three schedules with day and night shifts, and found the deleterious effects of multiple night shifts to be greater than those associated with long shifts.

The effects of sleep inertia wear off after 2-4 hours of wakefulness, such that most workers who wake up in the morning and go to work suffer some degree of sleep inertia at the beginning of their shift. The relative effects of sleep inertia vs. the other factors are hard to quantify, however the benefits of napping appear to outweigh the cost associated with sleep inertia.

Shift work management practices

The practices and policies put in place by managers of round-the-clock or 24/7 operations can significantly influence shift worker alertness (and hence safety) and performance.^{[citation needed]}

Air traffic controllers typically work an 8-hour day, 5 days per week. Research has shown that when controllers remain "in position" for more than two hours, even at low traffic levels, performance can deteriorate rapidly, so they are typically placed "in position" for 30-minute intervals (with 30 minutes between intervals).

These practices and policies can be fairly obvious: selecting an appropriate shift schedule or rota and using an employee scheduling software to maintain it, setting the length of shifts, managing overtime, increasing lighting levels, or providing shift worker lifestyle training to help shift workers better handle issues such as understanding basic circadian physiology, sleep and napping, caffeine usage, social life issues, diet and nutrition, etc. They may also be more indirect: retirement compensation based on salary in the last few years of employment (which can encourage excessive overtime among older workers who may be less able to obtain adequate sleep), or screening and hiring of new shift workers that assesses adaptability to a shift work schedule.

A day may be divided into three shifts, each of 8 hours, and each employee works just one of those shifts; they might, for example, be midnight to 08:00, 08:00 to 16:00, 16:00 to midnight. 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.

12-hour work shifts are also in use. In a modern steelworks, four sets of personnel are used, working consecutive days in one 12-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. The svingskift (literally: "swing shift") in the offshore petroleum industry in Norway refers to a two-week tour during which employees work 12-hour days the first seven days and 12-hour nights the second (or vice versa).

Shift work was once characteristic primarily of the 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. It contrasts with the use of overtime to increase production at the margin. Both approaches incur higher wage costs. Although 2nd-shift worker efficiency levels are typically 3–5% below 1st shift, and 3rd shift 4–6% below 2nd shift, the productivity level, i.e. cost per employee, is often 25% to 40% lower on 2nd and 3rd shifts due to fixed costs which are "paid" by the first shift.

In general, requiring workers to live on a time-shifted schedule for extended periods is unpopular, and this typically must be paid for at a premium. It is common in heavy industry, particularly automobile and textile manufacturing and is becoming more common in locations where a shut-down of equipment would incur an extensive restart process. Food manufacturing plants, in particular, have extensive cleaning programs that are required before any restart. The use of shift work in manufacturing varies greatly from country to country. Shift work is common in the transportation sector as well. Some of the earliest instances appeared with the railroads, where freight trains have clear (i.e. passenger-free) tracks to run on at night. Shift work has been traditional in law enforcement and the armed forces: for example sailors must be available to handle a vessel around the clock, and a system of naval watches organized to ensure enough hands are on duty at any time. This is shift work by another name.

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 Emergency Medical Services, police, fire prevention, security 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.

Much of the Internet services and Telecommunication industry relies on shift work to maintain worldwide operations and uptime.

Shift patterns

Panama Schedule

The Panama schedule follows a 3-2-2-3 pattern in which shift workers generally are allowed every other Friday, Saturday, and Sunday off, with two additional days off during the week, although this may differ depending on organization and industry. The most common form utilizes four shifts, each working twelve hours, with two shifts generally paired together (Alpha working days and Bravo working nights while Charlie and Delta are off, and vice versa). It is not uncommon for shifts to rotate between days and nights, most often with six months spent on nights and six on days. This shift is sometimes known as 2-2-3, or "two, two, and three".

Time	Sun	Mon	Tues	Wed	Thur	Fri	Sat	Sun	Mon	Tues	Wed	Thurs	Fri	Sat
06:00 to 18:00	Off	On	On	Off	Off	On	On	On	Off	Off	On	On	Off	Off

6 on 6 off

Consists of 3 days and 3 nights.Then 6 days off. These will alternate between other crews A.K.A teams for a full 24/7 operation.

Three-shift system

The "three-shift system" is the most common pattern, with "first" from 06:00 to 14:00, "second" from 14:00 to 22:00, and a "third" (or "night") shift from 22:00 to 06:00 This is generally worked over a five-day week; to provide coverage 24/7, employees have their days off ("weekends") on different days.

To provide an overlap in shifts, some employers may require one of the shifts to work four 10 hour shifts per week (as opposed to five 8 hour shifts, both are 40 hours per week). In that scenario, the night shift might extend from 21:00 to 07:00, but the night-shift would have nearly four days off (86 hours) between work weeks. This change, along with first shift moving a half hour later, or second moving a half hour earlier, ensures at least a half hour overlap between shifts, which might be desirable if the business is open to the public to ensure that customers continue to be served during a shift change.

Some states, such as California, accommodate this arrangement by allowing the employee to be paid at their regular rate (as opposed to time-and-a-half, or an overtime rate, that would normally be required for any time past 8 hours) for the 10 hour shift, calling this an "Alternative workweek."

All of the shifts have desirable and less desirable qualities. First shift has very early starts, so time in the evening before is heavily cut short. The second shift (or "swing shift") occupies the times during which many people finish work and socialize. The third shift creates a situation in which the employee must sleep during the day.

Generally, employees stay with the same shift for a period of time, as opposed to cycling through them; this is seen as healthier.^{[citation needed]}

Three-shift example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
06:00–14:00	Shift 1	Shift 1	Shift 1	Shift 1	Shift 1	Off	Off
14:00–22:00	Shift 2	Shift 2	Shift 2	Shift 2	Shift 2	Off	Off
22:00–06:00	Shift 3	Shift 3	Shift 3	Shift 3	Shift 3	Off	Off

Four on, four off

Four on, four off is a shift pattern that is being heavily adopted in the United Kingdom and in some parts of the United States.^{[citation needed]} An employee works for four days, usually in 12-hour shifts (7:00 to 7:00) then has four days off. While this creates a "48-hour week"(42-hour average over the year) with long shifts, it may be preferred because it shrinks the work week down to four days, and then gives the employee four days rest—double the time of a usual weekend. Due to the pattern, employees effectively work an eight-day week, and the days they work vary by "week". As with three-shift system, most employees stay with the same shift rather than cycling through them.

Four on, four off example:

Time 7:00-7:00	Sat	Sun	Mon	Tues	Wed	Thur	Fri	Sat
07:00–19:00	Day 1	Day 2	Day 3	Day 4	Off	Off	Off	Off

Navy Three-shift underway system

The US Navy uses a three shift system that relies on an 18 hour day instead of a 24 hour day. The 24 hour period is broken up into 4 shifts. 00-06, 06-12, 12-18, and 18-00. A sailor will stand watch on his shift. During his offgoing shift he will have time to perform maintenance, work on qualifications and handle all his collateral duties. During the oncoming time the sailor has time to sleep, relax, and do whatever personal things he needs to do like laundry. This does not apply to the attached air wing, which will work a 12 on 12 off schedule 7 days a week.

Navy Three-shift example: Shift 1

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
00:00–06:00	Shift 1	Offgoing	Oncoming	Shift 1	Offgoing	Oncoming	Shift 1
06:00–12:00	Offgoing	Oncoming	Shift 1	Offgoing	Oncoming	Shift 1	Offgoing
12:00–18:00	Oncoming	Shift 1	Offgoing	Oncoming	Shift 1	Offgoing	Oncoming
18:00–00:00	Shift 1	Offgoing	Oncoming	Shift 1	Offgoing	Oncoming	Shift 1

Navy Three-shift example: Shift 2

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
00:00–06:00	Oncoming	Shift 2	Offgoing	Oncoming	Shift 2	Offgoing	Oncoming
06:00–12:00	Shift 2	Offgoing	Oncoming	Shift 2	Offgoing	Oncoming	Shift 2
12:00–18:00	Offgoing	Oncoming	Shift 2	Offgoing	Oncoming	Shift 2	Offgoing
18:00–00:00	Oncoming	Shift 2	Offgoing	Oncoming	Shift 2	Offgoing	Oncoming

Navy Three-shift example: Shift 3

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
00:00–06:00	Offgoing	Oncoming	Shift 3	Offgoing	Oncoming	Shift 3	Offgoing
06:00–12:00	Oncoming	Shift 3	Offgoing	Oncoming	Shift 3	Offgoing	Oncoming
12:00–18:00	Shift 3	Offgoing	Oncoming	Shift 3	Offgoing	Oncoming	'Shift 3
18:00–00:00	Offgoing	oncoming	Shift 3	Offgoing	Oncoming	Shift 3	Offgoing

Four on, three off

Main article: Four-day week

Each employee works four days and gets a three-day weekend. For some types of manufacturing, this is a win-win arrangement. For example, Kyanize Paint Company had been making 3 batches of paint per day, Monday through Friday (3 × 5 = 15). They changed to making 4 batches of paint, Monday through Thursday (4 × 4 = 16). Total worker hours remained the same, but profits increased. In exchange for two additional hours of work per day, over 4 days, workers got an additional day off every week (see also the book, 4 Days, 40 Hours).

Four on, two off

In four on, two off the employee only gets two days off. In a seven-day period, this adds up to 60 hours worked (on average, based on 12-hour shifts). Four on, two off is mainly adopted by industries in which employees do not engage in much physical activity.

Four on, two off example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
07:00 to 19:00	Day 1	Day 2	Day 3	Day 4	Off	Off	Day 5

Four on, one off

In four on, one off the employee only gets one day off. In a seven-day period, this adds up to 48 hours worked (on average, based on 8-hour shifts). Four on, one off is mainly adopted by industries in which companies prefers to work for all days of the week with four shifts and where laws do not let employees work for 12 hours a day for several days.

Four on, one off example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
07:00–15:00	Day 1	Day 2	Day 3	Day 4	Off	Day 5	Day 6

Two days, two nights, four off

A variation is the two days, two nights, four off pattern of working. In this shift schedule, employees work 12-hour shifts from 06:00 to 18:00 on day shifts and from 18:00 to 06:00 on nights. This pattern is currently in use by HM Coastguard in the UK, and employs four separate teams to maintain 24/7 coverage.

Two days, two nights, four off example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri	Sat
06:00–18:00	Day 1	Day 2	Off	Off	Off	Off	Off	Off
18:00–06:00	Off	Off	Day 3	Day 4	Off	Off	Off	Off

5/4/9s

"5/4/9s" (or "Five/Four Nines", or "9/80") is another variation. Employees work in 2 week cycles. Week 1 the employee works 4 days of 9 hours followed by 1 day of 8 hours with 2 days off (week 1: 44 hours). Week 2 the employee works 4 days of 9 hours with 3 days off (week 2: 36 hours). This pattern works to 80-hours in a 2 week pay-period (comparable to working 8 hours a day for 5 days a week). The benefit to working an extra hour a day gives you a "normal" 2 day weekend followed by a long 3 day weekend the next. Typical working hours for this type of shift would be 06:00 to 15:30 (9 hours with 30 minutes lunch) and 06:00 to 14:30 (8 hours with 30 minutes lunch) on the 8-hour work day. Often the employer will alter the starting times (e.g., start at 07:00 or 08:00). Also referred to as "9/80" as employees have nine days to work 80 hours.

5/4/9s shift example:

Week	Mon	Tues	Wed	Thur	Fri	Sat	Sun
Week 1	9 hrs	9 hrs	9 hrs	9 hrs	8 hrs	Off	Off
Week 2	9 hrs	9 hrs	9 hrs	9 hrs	Off	Off	Off

12/24/12/48

12/24/12/48 (or 12/24) is another variation. Employees work in shifts of 12 hours; first a daily shift (e.g., 07:00 to 19:00), followed by 24 hours rest, then a nightly shift (19:00 to 07:00), finishing with 48 hours rest. This pattern needs four teams for full coverage, and makes an average 42-hour workweek.

12/24/12/48 shift example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
06:00–18:00	Day 1	Off	Off	Off	Day 3	Off	Off
18:00 to 06:00	Off	Day 2	Off	Off	Off	Day 4	Off

Continental shift

Continental shift, adopted primarily in central Europe, is a rapidly changing three-shift system that is usually worked for seven days straight, after which employees are given time off. For example, three mornings, two afternoons, and then two nights.

Continental shift example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
06:00–14:00	Shift 1	Shift 1	Shift 1	Off	Off	Off	Off
14:00 to 22:00	Off	Off	Off	Shift 1	Shift 1	Off	Off
22:00–06:00	Off	Off	Off	Off	Off	Shift 1	Shift 1

Split shift

Main article: Split shift

Split shift is used primarily in the catering, transport, hotel, and hospitality industry. Waiters and chefs work for four hours in the morning (to serve lunch), then four hours in the evening (to serve an evening meal). The average working day of a chef on split shifts could be 10:00 to 14:00 and then 17:00 to 21:00

Split shift example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
10:00–14:00	On	On	On	On	On	Off	Off
14:00–17:00	Off	Off	Off	Off	Off	Off	Off
17:00–21:00	On	On	On	On	On	Off	Off

Earlies and lates

Earlies and lates is used primarily in industries such as customer service (help desk/phone-support), convenience stores, child care (day nurseries), and other businesses that require coverage greater than the average 9:00 to 5:00 working day in the UK. Employees work in two shifts that largely overlap, such as early shift from 08:00 to 16:00 and late shift from 10:00 to 18:00

Earlies and lates shift example:

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
08:00–16:00	Shift 1	Shift 1	Shift 1	Shift 1	Shift 1	Off	Off
15:00–23:00	Shift 2	Shift 2	Shift 2	Shift 2	Shift 2	Off	Off

7-day fortnight shift

In the 7-day fortnight shift pattern, employees work their allotted hours within 7 days rather than 10. Therefore, 41 hours per week equate to 82 hours per fortnight (fourteen days and nights), which is worked in seven days, at 11–12 hours per shift. This shift structure is used in the broadcast television industry, as well as many law enforcement agencies, as well as health care fields such as nursing and clinical laboratories in the US.

7-day fortnight shift example:

Week 1

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
Days 08:00 to 20:00	Shift 'A' Day 1	Shift 'A' Day 2	Shift 'C' Day 1	Shift 'C' Day 2	Shift 'C' Day 3	Shift 'A' Day 3	Shift 'A' Day 4
Nights 20:00 to 08:00	Shift 'B' Night 1	Shift 'B' Night 2	Shift 'D' Night 1	Shift 'D' Night 2	Shift 'D' Night 3	Shift 'B' Night 3	Shift 'B' Night 4

Week 2

Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
Days 08:00 to 20:00	Shift 'C' Day 4	Shift 'C' Day 5	Shift 'A' Day 5	Shift 'A' Day 6	Shift 'A' Day 7	Shift 'C' Day 6	Shift 'C' Day 7
Nights 20:00 to 08:00	Shift 'D' Night 4	Shift 'D' Night 5	Shift 'B' Night 5	Shift 'B' Night 6	Shift 'B' Night 7	Shift 'D' Night 6	Shift 'D' Night 7

One of the advantages of using this pattern is each shift pair, for example A and B, will get time off on weekends alternatively, because the schedule is fixed and does not drift.

DuPont 12-Hour rotating shift

The DuPont 12-Hour rotating shift provides 24/7 coverage using 4 crews and 12-hour shifts while providing a week off. Average hours is 42 per week but contains a 72-hour week which can be challenging. It is used in several manufacturing industries in the US. Companies that have gone to this schedule have noticed a decrease in accidents plus more rest for employees, less call ins, and more coverage when crews are short handed. In all the schedule is designed to improve safety.

DuPont 12-Hour rotating shift example:

Week	Fri	Sat	Sun	Mon	Tues	Weds	Thurs
1	Nights	Nights	Nights	Nights	Off	Off	Off
2	Days	Days	Days	Off	Nights	Nights	Nights
3	Off	Off	Off	Days	Days	Days	Days
4	Off	Off	Off	Off	Off	Off	Off

Five and two

The five and two provides 24/7 coverage using 4 crews and 12-hour shifts over a fortnight. Average hours is 42 per week but contains a 60-hour week which can be challenging.

Five and two shift example:

Week	Fri	Sat	Sun	Mon	Tues	Weds	Thurs	Fri	Sat	Sun	Mon	Tues	Weds	Thurs
1	Nights	Nights	Nights	Off	Off	Nights	Nights	Off	Off	Off	Days	Days	Off	Off
2	Days	Days	Days	Off	Off	Days	Days	Off	Off	Off	Nights	Nights	Off	Off
3	Off	Off	Off	Swing	Swing	Off	Off	Swing	Swing	Swing	Off	Off	Swing	Swing
4	Off	Off	Off	Days	Days	Off	Off	Days	Days	Days	Off	Off	Days	Days

Seven-day eight-hour rotating shift

The seven-day eight-hour rotating shift provided 24/7 coverage using 8-hour shifts with 14 crews. Consisted of a morning shift from 07:00 to 15:00, a swing shift from 15:00 to 22:30 and a night shift from 22:30 to 07:30 Each shift was worked for five days straight. The 8-hour shifts allowed vacations and absences to be covered by splitting shifts or working double shifts. The run of day shifts was 56 hours but the 8-hour shift provided time for some socializing after work. Was once common in the pulp and paper industry in the Western United States but has been largely replaced by a 8 days, 8 swing, 5 nights, 9 off, 8-hour rotation.

Seven-day eight-hour rotating shift example:

Week	Sun	Mon	Tues	Weds	Thurs	Fri	Sat
1	Day	Day	Day	Day	Day	Off	Off
2	Swing	Off	Off	Swing	Swing	Swing	Swing
3	Night	Night	Off	Off	Night	Night	Night
4	Day	Day	Day	Day	Off	Off	Day
5	Swing	Swing	Swing	Swing	Swing	Off	Off
6	Off	Night	Night	Night	Night	Night	Off
7	Off	Off	Day	Day	Day	Day	Day
8	Swing	Swing	Swing	Swing	Swing	Off	Off
9	Night	Off	Off	Night	Night	Night	Night
10	Day	Day	Off	Off	Day	Day	Day
11	Swing	Swing	Swing	Off	Off	Swing	Swing
12	Night	Night	Night	Night	Off	Off	Night
13	Day	Day	Day	Day	Day	Off	Off
14	Off	Swing	Swing	Swing	Swing	Swing	Off
15	Off	Off	Night	Night	Night	Night	Night

Sixes

Submarine sailors in the American Navy engage in a pattern known as sixes while underway. Instead of a 24-hour day, the ship operates on an 18-hour schedule. Any given individual is scheduled to stand watch for 6 hours, perform any other duties and engage in leisure time for 6 hours, then sleep for 6 hours. If enough personnel are available, a given watchstation may benefit from a fourth man referred to as the midnight cowboy. He will stand the same 6-hour watch in a given 24-hour period, usually from midnight to 06:00 (hence the midnight portion of the name, which is most often shortened to just cowboy) and the person who would normally stand that watch is free. This gives rise to a schedule of six on, twelve off, six on, thirty off, six on, twelve off.

Firefighting schedules

In many departments, firefighters work 24-hour shifts. They are authorized to sleep in the fire station at night but are still subject to calls for service the entire shift. Most departments split the 168 hour long week between 3 or 4 work groups (sometimes referred to as 'shifts' or 'platoon groups'), resulting in a 56 or 42 hour workweek, respectively. Some departments reduce the average workweek by scheduling an extra day off for each firefighter in the work group, frequently reducing a 56 hour workweek to a 48 hour workweek by scheduling a 24 hour "Kelly Day" every three weeks. Departments have many options for scheduling firefighters for coverage. One option is 24 on/48 off, where a firefighter will work 24 hours and have 48 hours off, regardless of the day of the week or the holidays. Often they will be scheduled in an A–B–C pattern. Thus, a firefighter will be assigned to A, B or C shift and work whenever that letter is on the calendar.

Most departments have found that a 24 hour work shift, with opportunistic sleeping between calls for service, is a valid means of avoiding some of the health and cognitive problems associated with shift work.

Three-Platoon schedules

24/48

The most basic three-platoon schedule is a straight rotation of 24-hour shifts among three platoon groups. This rota limits time off to 48 hours in a row, less than 66 hours off in a row most workers get each weekend. Workers on this schedule only get one short weekend off every three weeks, making it difficult to perform the social grooming required to build the support networks necessary to deal with the stressors associated with emergency response. Twenty-four hours off-duty is also the minimum required to completely recover from a period of acute sleep deficit.

Week	Mon	Tues	Wed	Thur	Fri	Sat	Sun
Week 1	A	B	C	A	B	C	A
Week 2	B	C	A	B	C	A	B
Week 3	C	A	B	C	A	B	C

California roll shift schedule

Another option is known as a California roll, where some shifts will be close together but allow for several days off. This option gives a 96 hour break every 9th day, which is contiguous to the conventional weekend on two of nine weekends, with a third weekend providing a break that starts on Saturday morning. There is an opportunity to accumulate sleep debt over the three days of work, however this debt should be completely cleared over the four day break. The nine-day rota that is repeated to fill the calendar is this:

	Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
Week 1	07:00 to 07:00	A	B	A	C	A	C	B
Week 2	07:00 to 07:00	C	B

where a firefighter will work 24 hours on, 24 off, 24 on, 24 off, 24 on, 96 hours (4 days) off.

Modified California Roll

This rotation reduces the chronic sleep deficit accrued over the first two work days at the expense of a shorter long break. This schedule's long break coincides with a standard weekend exactly once every nine weeks. The four day break could be retained by working a fourth day in the rotation - XOXOOXOXOOOO.

	Time	Sat	Sun	Mon	Tues	Wed	Thur	Fri
Week 1	07:00 to 07:00	A	B	A	B	C	A	C
Week 2	07:00 to 07:00	A	B	C	B	C

where a firefighter will work one day, off one, work one, off two, work one, off four days.

48/96

A number of departments have investigated further work consolidation by allowing for a 48 hour work shift. Careful demand management would be required to avoid acute sleep deficit, however, firefighters should return to work fully recovered from the previous shift. XXOOOOXXOOOO.

3-3-3

Kenneth B. Ellerbe chief of the District of Columbia Fire and Emergency Medical Services Department has proposed a schedule where firefighters work three day shifts, followed by three night shifts, followed by three days off. It is likely that such a schedule would impact all four alertness factors associated with shift work, and result in a threat to public safety. It would result in exactly one break coinciding with the standard weekend every nine weeks. DDDNNNOOODDDNNNOOO

Four-platoon shift schedules

24/72

The most basic four-platoon schedule is a straight rotation of 24-hour work shifts between four work work groups or platoons. This schedule works 48 hours per week for three weeks and 24 hours the fourth week, averaging 42 hours per week.

Week	Mon	Tues	Wed	Thur	Fri	Sat	Sun
Week 1	A	B	C	D	A	B	C
Week 2	D	A	B	C	D	A	B
Week 3	C	D	A	B	C	D	A
Week 4	B	C	D	A	B	C	D

24/48/24/96

Another variation of the 24-hr shift schedule is a 4-platoon system, averaging 42 hours/week. Thus, the schedule is 24 on, 48 off, 24 on, 96 off, on a 4-day rotation.

Week	Mon	Tue	Wed	Thu	Fri	Sat	Sun
Week 1	A	D	B	A	C	B	D
Week 2	C	A	D	B	A	C	B
Week 3	D	C	A	D	B	A	C
Week 4	B	D	C	A	D	B	A
Week 5	C	B	D	C	A	D	B
Week 6	A	C	B	D	C	A	D
Week 7	B	A	C	B	D	C	A

Although the performance benefits of shorter shifts may not outweigh the performance costs of consecutive nights of work, some departments with four platoon groups work shorter shifts. Most such departments work a 10 hour day and a 14 hour night tour. This enables the firefighter to get relieved from work in the afternoon, commute home, spend time with family, and get a good night's sleep before returning to work in the morning. Schedules that only allow 12 hours, or less, between work shifts do not allow enough time to incorporate a healthy night of sleep, and therefore begin to accumulate sleep deficit even when the employee is working days.

2-2-4

On this schedule, firefighters work two 10 hour days, two 14 hour nights, and then have four days off. In the Canadian Firefighter study, consecutive nights were shown to be more deleterious to performance than a single, long shift. After two consecutive nights, performance effectiveness was reduced to 75%, vs. 78% on a 24 hour shift. If the schedule induces sleep deficit during the day shift, this performance would be worse. This schedule's long break aligns with the conventional weekend for exactly two weeks out of eight. The rota is: DDNNOOOO.

2-2-3

This schedule is also known as the Panama Schedule above, however, when firefighters work it, the shifts rotate from days to night between every break. Since the firefighters have a two day break before any nights worked, they do not start the series of nights with an employment-related sleep deficit. They do work three nights in a row, which would result in chronic sleep deficit if alarms are received on each night, however, the third night is always a Sunday night, which is often less busy than other nights of the week. This schedule allows for a long break every other weekend. The rota is DDOONNN OODDOOO NNOODDD OONNOOO

Graveyard shift

Graveyard shift, night shift or third shift (3rd shift) means a shift of work running through the early hours of the morning, especially shifts from midnight until 08:00 or from 23:00 until 07:00. There is no certainty as to the origin of this phrase; according to Michael Quinion it is little more than "an evocative term for the night shift … when … your skin is clammy, there's sand behind your eyeballs, and the world is creepily silent, like the graveyard."

In 2007, the World Health Organization (WHO) announced that working the graveyard shift would be listed as a "probable" cause of cancer.

Industries

Industries requiring 24/7 cover are those that employ workers on a shift basis, for example:

• Casino
• Customer service including call centers
• Death care (medical examiner or coroner)
• Emergency response systems
  • Firefighting
  • Paramedic services
  • Police
• Funeral
• Boeing Flight Test
• Health care
• Logistics
• Hospitality
• Manufacturing
• Military
• Retail
• Telecommunications
  • Television
  • Radio broadcasting
• Transportation
  • Railroads
• Security
• Public utilities
  • Nuclear power
  • Fossil fuel
  • Solar, wind, and hydro power

See also

• Circadian rhythm sleep disorders
• Eight-hour day
• Hospital
• Schedule (workplace)
• Sleep
• Split shift
• Timebar scheduling

Further reading

• Knutsson, A., Åkerstedt, T., Jonsson, B.G. & Orth-Gomer, K. (1986) 'Increased risk of ischaemic heart disease in shift workers'. Lancet, 2(8498), 89–92.
• Burr, Douglas Scott (2009) 'The Schedule Book', 'ISBN 978-1-4392-2674-2'.

External links

• Scientific Symposium on the Health Effects of Shift Work, Toronto, 12 April 2010, hosted by the Occupational Cancer Research Centre and the Institute for Work & Health (IWH).
• Three-hour night shift system, For a crew of three on a small boat at sea