Advantages and disadvantages of 12-hour shifts


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Longer shifts have become increasingly popular with workers in 24/7 operations. However, some managers still have reservations due to concerns about safety and productivity. Let’s explore each group’s perspective. After that, we’ll discuss a couple of scheduling issues related to 12-hour shifts.

Shiftworker Opinions

In surveys of over 20 thousand shift workers, 74% said they would like to work more hours a day in order to get more days off each week. With each of our larger clients, we show the workforce several different schedule options that satisfy the client’s business coverage requirements. By educating employees about the various possibilities, they are able to make more informed choices from the schedule alternatives. The options we show employees typically include one or more 8-hour, combined 8 & 12-hour, and 12-hour schedules. Roughly 90% of the time, the highest-rated schedules consist of 12-hour shifts.

Reasons for the popularity of 12-hour shifts among shift workers:

  • More days off. In a 24/7 operation with 8-hour shifts, there are 91 scheduled days off per year. With 12-hour shifts, there are twice as many (182 days off per year). These numbers are based on 4-crew schedules with level coverage requirements. Benefits of the extra days off include reduced commuting expenses, less need to take paid time off for doctor appointments, school meetings, or personal activities, and improved morale as a result of better work/life balance.
  • More weekends off. The maximum possible number of full weekends off with 8-hour shifts is 13 per year. The most common schedules that accomplish this require employees to work 7 days in row. 8-hour schedules that feature 5 or 6 days of work in a row only provide 5-6 weekends off per year. The maximum possible number of full weekends off with 12-hour shifts is 26 per year. Unlike the 8-hour schedules, this can be achieved under a variety of configurations with a maximum of 4 consecutive days of work.
  • Longer breaks. In contrast with most 8-hour shift schedules that provide a maximum of 4 days off, 12-hour schedules can provide up to 8 consecutive days off. And, by strategically taking 48 hours of vacation, the break can be extended to as much as 2 full weeks. Longer breaks mean more time to recover from the sleep debt incurred while working the longer shifts.
  • Other benefits. This includes things like the elimination of double shifts to cover absences and the elimination of afternoon shifts (an unpopular shift for employees with families).

While longer shifts are certainly popular nationwide, they are not the unanimous preference of all shift workers. Employees who are older, have childcare concerns, are going to school, have second jobs, or participate in other non-work activities on work days often prefer 8-hour or combined 8 & 12-hour shift schedules. Other disadvantages of 12-hour shifts are:

  • Long hours. Not only is 12 hours a long time to work, but if you add in commute time and meal breaks, this can be a very long day. This leaves little time for anything but eating and sleeping.
  • Irregular pay weeks. Half the work weeks will be 48 hours and half will be 36 hours. Depending on the schedule selected, these may not occur in alternating weeks. For example, with one on-off pattern there are four consecutive 48-hour weeks followed by four consecutive 36-hour weeks. Unless the organization is able to balance the paychecks, employees will find this tough to budget for.
  • Absence coverage. Instead of holding someone over to cover an absence, the organization now must call someone in from a scheduled day off. If there is a high absence rate, this can defeat the primary advantage of the longer shifts, namely more days off.


Management Opinions
Managers are sometimes reluctant to adopt 12-hour shifts because they believe alertness and productivity decline after 8 hours of work. The more you read on the subject, the more confused you get. Some researchers have concluded that the longer shifts were detrimental to productivity and safety; others say that things got better after workers changed to 12-hour shifts. A good place to review the research is a report by the Police Foundation called The Shift Length Experiment. Here’s a link to the report:

We believe that the differing conclusions stem from comparing dissimilar situations. Researchers may have compared one group on an 8-hourfixed shift schedule with another group on a 12-hour rotating shift schedule. They didn’t factor in different schedule variables, such as the on-off work pattern, the amount of overtime, shift start times, and so on. They also didn’t consider worker characteristics or the work environment. Problems they attribute to working longer shifts most likely are the result of these other factors in combination with the shift length.


Based our experience with organizations that have adopted longer shifts, we have not found problems as long as the schedule is well designed, with sufficient time off and reasonable limits on the number of consecutive days worked. Our surveys show that over a period of time, shift workers on 12-hour shifts actually get more sleep than those on 8-hour shifts. They may get less sleep on the days they work the 12-hour shifts, but they get twice as many days off. Since everyone sleeps longer on their days off, the average sleep with 12s is greater than the average sleep with 8s.


Average Hours of Sleep Over a Four-Week Period:   8-Hour vs. 12-Hour Shifts

Schedule Shift Length Days of Work Hours of Sleep Days    Off Hours of Sleep Average
Days only 8 hours 21 6.5 7 7.5 6.8
12 hours 14 6.3 14 7.5 6.9
Nights only 8 hours 21 6.1 7 7.5 6.5
12 hours 14 6.2 14 7.5 6.9
Rotating shifts 8 hours 21 6.5 7 7.5 6.7
12 hours 14 6.3 14 7.5 6.9

As a result, 12-hour shifts actually have several benefits for management:

  • Better productivity. In addition to less sleep debt, workers only have two shift turnovers a day instead of three. Since shift transitions are a common source of slow-downs and errors, productivity tends to be improved with fewer of them. Accountability also seems to rise with 12s. Problems are fixed right away rather than passing them on to the next shift. And projects are more likely to be finished by the same crew that started them.
  • Reduced absenteeism. One reason is that workers have more time off during the week to attend to personal obligations. Another reason is that they don’t want to take a full 12 hours off for a one-hour appointment. Finally, they tend to be more accountable because they know someone has to be called in from a day off to fill the vacancy.
  • Lower turnover. Since employees like the longer shifts, they are less likely to seek other jobs or occupations.
  • Employee attention. On the days they work 12-hour shifts, employees tend to avoid social events, excessive alcohol consumption, or physically exhausting activities. This means they are more attentive and dedicated to the work.

There are some jobs that are not suited to longer shifts (such as tedious detail inspections). Jobs with exposure to extreme heat, loud noises, toxins or heavy physical labor may simply be too much to endure for more than 8-hours. Other disadvantages for management include:

  • Long hours. Even though employees get more sleep over time, their alertness and attention span may not last a full 12 hours. Sitting at a terminal or work station for 12 hours straight can increase the likelihood of ergonomic problems. Jobs may have to be redesigned to compensate for this.
  • Absence management. It becomes harder to cover absences since you can’t rely on holding someone over. Larger companies can purchase software that makes it easier to select and contact candidates. Smaller companies that can’t afford the software may find that supervisors are spending a large percentage of their time trying to fill the vacancies.
  • Second jobs. Employees may find it easier to take on a second job. Instead of spending their time off recuperating, they will be working elsewhere. This could affect their alertness and dedication.
  • Long breaks. Employees may love them, but things can change at work while they are gone. Employees will take longer to get back up to speed and to learn procedures and directions. Managers can alleviate this by avoiding 12-hour work patterns that have long breaks.
  • Communication. Since employees work only half as many days, there are fewer opportunities for personal interaction with management and support staff. Holding information meetings often require employees to stay longer than 12 hours which means lack of attention and increased risk of accidents during the commute afterward.
  • Training. Unless time for training is built into the schedule, formal training must be done on the employees’ days off. If training is voluntary, attendance may decline as a result.


Scheduling Considerations
Once you’ve decided that 12-hour shifts would be a good choice, it’s tempting to search the Internet for “free 12 hour shift schedule examples.” Eventually you’ll find samples of popular patterns such as the 2-3-2 (aka Pitman or Panama), super long break (aka DuPont), 3-on-3-off, 4-on-4-off, etc. Before you do that, please keep the following points in mind:

  • Staff size. Most 12-hour schedules use 4 crews. If your staff size is not a multiple of four (4, 8, 12, 16, etc.), these schedules would not be a good choice, since they would not make efficient use of your staff and would produce inconsistent coverage. You need a 12-hour pattern that is custom-designed to match the actual number of people working the schedule.
  • Coverage. Most 12-hour shift schedules produce steady coverage – the same on both shifts, every day of the week. 12-hour fixed shift schedules can have different coverage on each shift by changing the crew sizes, but the coverage will remain the same all week. If your workload and coverage requirements aren’t constant, popular schedule patterns won’t make effective use of your staff. If you need extra coverage for 8 or 16 hours a day, you may need to combine 12-hour shifts with one or two 8-hour overlay shifts. If you need less coverage on Saturday and Sunday, you need a custom-designed pattern.
  • Overtime/pay week. Most schedules work best for a specific week (e.g., Sun-Sat). If your overtime/pay week is different from the ideal for a specific pattern, this could result in unnecessary overtime and loss of maximum weekends off. Some patterns can be modified to work with different pay weeks; some can’t. Free schedule templates never mention this. They imply that the starting day is unimportant. Actually the pay week is just as important as the staff size and coverage requirements.

We can help you find the best 12-hour shift schedule for your resources and requirements:

  • Feasibility. If you’re unsure if you have enough staff, try our Staffing Calculators. You also may want to read my recent blog post on matching 12-hour shifts to your workload distribution: You can always give us a call at (415) 717-3754 or shoot us an email at
  • Examples. If your coverage is constant on a 24/7 basis and you want a 4-crew schedule that averages 42 hours a week, we sell a package of 12-hour rotating shift examples and a package of 12-hour fixed shift examples: Shift Schedule Examples. This is the best way to see the full range of possibilities. Don’t limit your search to a single schedule template you found somewhere on the Internet. We offer 10 different options with fixed shifts and 10 different options with rotating shifts.
  • Custom design. If your group covers less than 24/7, your staff is not a multiple of 4, the coverage is not constant, you want a schedule that is matched to your pay week, or you want a schedule that averages 40 hours a week, you will need a custom-designed 12-hour schedule: Custom Schedule Design.

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