Let me explain.

Most people working the night shift tend to stay awake during the daytime on their days off (roughly 75% of the people on 12-hour shifts and 50% on 8-hour shifts). With the 2-3-2 pattern, this means that every 2 or 3 days, people are flip-flopping when they sleep. This can be really tough on sleep and alertness. In fact, it's even worse than most rotating shift schedules that rotate on a weekly basis.

Another problem with the Pitman has to do with the organization's overtime/pay week, since that dictates what days you get off for the weekend. If your pay week begins on Mon, Wed, or Fri, the 3-day weekend will be Sat, Sun, Mon instead of Fri, Sat, Sun. For the night shift, this means you have to work Friday night, so it really doesn't feel like you're getting the whole weekend off.  

If your schedule has fixed shifts, I recommend that each shift select it's own pattern. This way the day shift can work the Pitman while the night shift can work something else that is better for alertness and safety. The best choice on the night shift is the 4-on-4-off shift schedule. That's because there are fewer changes from work-days to off-days, meaning a slower rotation of when people sleep. Other 12-hour patterns lie somewhere in between these two extremes: Pitman and 4-on-4-off.

Here is what I recommended:

• Shift length. Most companies that change to 24/7 end up adopting 12-hour shifts. Not all, but a substantial majority. However, since this company was located in California and not represented by a union, it would have to pay overtime after 8 hours a day. This would make 12-hour shifts too expensive, leaving them with no choice other than 8-hour shifts.
  
  
• Schedule format. In general, employees prefer fixed shifts while management prefers rotating shifts. Since this company would be using 8-hour shifts, the choice was obvious. 8-hour fixed shifts often require a few more employees than rotating 8-hour shifts, making them a much more expensive choice. Because of this, I recommended that they stay with the rotating shifts. I also warned them that with 24/7 schedules, the employees would change shifts every week rather than every 6 weeks like the are doing now.
  
  
• Shift differentials. The purpose of the shift differential is to attract employees to the less desirable shifts. Since the company was using rotating shifts, everyone was working those shifts. There was no need for an incentive. Shift differentials are only appropriate for fixed shifts. With rotating shifts, they are nothing more than a wage increase. To keep the employees' pay the same, the company should replace the differential with an across-the-board pay increase.
  
  
• Shift start times. Early start times for the day shift will result in fewer hours of sleep. When you combine this with the rotating shifts, it's a double whammy. I recommended changing the day shift to start no earlier than 6 a.m.
  
  

I've run into other companies preparing for continuous operations that were considering transitional changes that would have made the final step to 24/7 much more difficult or that would have locked them into a more costly position. That's why it's important to visualize the key features of the 24/7 schedule in advance, so that the preparatory steps are in alignment.

Let's face it, overtime disrupts people's lives. They have plans that get changed at the last minute. They are forced to work when they had other plans. How do they respond? Forfeiting sleep is one of the most common ways employees try to recover time off lost to overtime.

How much overtime is too much is a difficult question to answer. Most companies feel that an annual average of between 5% and 15% is about right. However, there are a lot of considerations other than alertness that go into finding the perfect amount for any operation. You may wish to read a more complete article on the impact of high overtime (http://www.shift-schedule-design.com/preview/uploaded/files/Overtime%).

Here is a quick summary from the above referenced article. "Our surveys of shiftworkers show that, on average, they get 21% less sleep time on the days they work than the days they are off. When employees work lots of overtime, they don't get time off to recover or catch up on their sleep. This, in turn, can lead to fatigue and reduced alertness. Managers simply cannot ignore the possibility of increased safety and quality incidents under these conditions."

People judge their work schedule, not by when they have to come to work, but by when they can stay home. In short, they focus on their time-off.

What people really want is a schedule that minimizes the conflicts between when they want to be off work and when they can be off work. There is rarely a perfect fit and you will never find a workforce where 100% of the people want the same thing. However, minimzing a majority of the schedule conflicts should be your goal.

Why? When there is a conflict, people will find a way to do what they want to do, often at the expense of sleep. Less conflict equals better sleep patterns, which results in higher alertness and better performance.

There is no pattern that is "best" fo every employee demographic. If you want to know what your workforce wants - ask them.

In this post, we're going to take a brief look at the impact of the schedule format, i.e. fixed vs. rotating shifts. This is an important scheduling decision all organizations must make. Should the employees only work a single shift or should they periodically rotate through all the shifts?

You can read the pros and cons from the employee and management perspectives elsewhere on my website (http://www.shift-schedule-design.com/Fixed_Shifts). As you can see, this is a pretty complex decision. For the single issue of alertness, however, the answer is simple: Fixed shifts are the best, period. There is substantial research showing that rotating shifts have higher health risks and lower overall alertness than fixed shifts.

I would never base the decision on fixed vs. rotating shifts (what I commonly call the schedule format) on alertness alone. But since this series of blog posts is focused on fatigue in the workplace, skipping this scheduling variable would be inexcusable.

People get less sleep on the days they work than the days they are off. With each consecutive day of work, they fall farther and farther behind in their sleep, or what is commonly referred to as sleep debt. Sleep debt accumulates and is very subtle. People don't realize they are losing a small bit of cognitive ability every day their sleep debt builds up. With each passing night, they come to work less safe and less productive.

Reducing the number of consecutive days of work, gives employees time off to catch up on their sleep and pay off some of the sleep debt. While the number of days needed to fully recover is uncertain, most researchers believe that at least 2 days off in a row are needed to have a recuperative impact.

The problem with reducing the number of consecutive days of work, of course, is that the number of weekends off can drop dramatically, especially with 8-hour shifts. There is no easy solution to this. The schedules we design never exceed 7 consecutive 8-hour shifts or 4 consecutive 12-hour shifts. Only in special circumstances do we feel that these limits can be exceeded safely.

Intuitively, you would think that the longer the work day, the less sleep you would get. To a certain extent, this is right. We have found that people working a 12-hour shift get about 10 minutes less sleep per night than people working an 8-hour shift. But that's not a complete picture since it is only looking at the days of work.

People on longer shifts get more days off. Workers on 12-hour shifts will get 87 more days off each year than those on 8-hour shifts. Since people sleep more on their days off than they do on the days of work, the people on 12s actually will average more sleep than those on the 8-hour work days. Here's a link to a table showing the details: http://www.shift-schedule-design.com/12-Hour_Shifts. You may have to scroll down a couple of times to find the table.

What do think? Counter-intuitive isn't it?

In the first post, I noted that employees don't think they need more than 7 hours sleep. Managers may want to post articles explaining the impact of sleep debt and the need for more than 7 hours of sleep a day. Just run a Google search for "sleep debt" and copy of few of the articles. If you can find anything by William Dement, he is the subject matter expert. I doubt that doing this will change employee behavior, but it may help to justify any actions management undertakes to address fatigue.

This post draws from a previous post in which I showed how early shift start times reduce the average hours of sleep for day shift workers (http://www.shift-schedule-design.com/Blog?m8:post=problems-with-early-morning-start-times). To summarize, people who start work at 7 a.m. sleep about 20 minutes more per night than those who start a 6 a.m.

Changing shift start times is difficult because people build their lives outside of work around the shift start and end times. When I review employee surveys, they often list the pros and cons of early start times. They say that the best thing about their current schedule is that they get off early, giving them time to do all sorts of things. Then they turn around and say that the worst thing about their schedule is having to get up so early and always feeling tired. How do you resolve this dilemma? It's both the best and worst features of your schedule - at the same time.

The other consideration with shift start times is traffic congestion. Later shift start times may require employees to spend extra time commuting. This takes time away from other activities. For those "other" activities to continue to take place, sleep is often the first thing sacrificed. Although many companies flex their hours to allow commuters to minimize time spent in traffic, this can be challenging for those with shiftwork operations. 

Early start times affect more than just shift workers. I've seen articles about the impact of early school start times on student performance. Teenagers have an internal clock that makes it difficult for them to be alert early in the morning, suggesting that learning would improve if schools started at 9 a.m. instead of 8 a.m.

Employee surveys show that most people think they only need 7 hours of sleep per night, yet they are actually getting much less than that. People readily exchange sleep for other activities, thinking there is little harm.

The fact is they need 8 hours. The result is a continual build-up of sleep debt as they get less sleep than they need night after night. After two weeks of mild sleep deprivation, cognitive abilities approach those of someone who is legally drunk.

Convincing employees that getting less than 8 hours of sleep is unsafe and unhealthy is not an easy task. Even if they believe that to be true, they still feel the sacrifice is worth the extra time spent with family, friends, hobbies, or simply watching TV.

I'm going to post a few more blogs on some of tactics managers can use to address fatigue in the workplace. If you have any horror stories you'd like to share, please feel free to post a comment.