After the Great Recession, many manufacturers had to find new ways to increase productivity and efficiency. Some changed their shift schedules from eight to 12 hours so they lost less production time on shift changes each day.

But there’s always a trade-off. The challenge has been finding the reasonably acceptable shift configuration that provides the most productive use of machinery, has the highest yield of acceptable product and the best application of supervision and available labor.

Major questions for companies considering 12-hour shifts include “How will 12-hour shifts affect the health and well-being of employees?” and “How will they improve the bottom line?"

Here are some things to consider when you evaluate whether a shift change is right for your facility and your workers.

Scheduling Issues

Fewer shift changes mean fewer opportunities for mistakes to happen. Slowdowns in operational efficiency, such as missing monitoring alerts or communication breakdowns, tend to occur during the transition between shifts.

Scheduling 12-hour shifts is also less complicated and consumes less administrative time.

Yet most workers and managers are accustomed to working 8-hour shifts, making those shifts easier to handle from the employee relations point of view.

Work/Life Balance

Workers who like 12-hour shifts value the extended time off, which improves morale and reduces absenteeism. The longer shift allows enough time to work another job or go to school during the three-day weekends.

While extended time off is a welcome advantage, 12-hour shifts can also be disruptive to family life and personal health by creating long-term stress. When circadian rhythms--the body’s natural wake-sleep cycles are--disrupted over prolonged time periods, significant emotional and physical problems can result.

The biggest concern with 12-hour shifts is lack of sleep and fatigue, which can negatively impact performance, productivity, and safety- on the job and at home. Health professionals typically agree that quality sleep is essential for maintaining good health. Most adults require seven to eight hours of sleep for optimal functioning; however, the Centers for Disease Control and Prevention reports that 30% of the nation’s workers are sleeping less than six hours per day.

In addition to fatigue, not getting enough sleep can result in shortened attention spans, memory lapses, and irrational decision-making. According to sleep experts, other sleep-related problems are diminished psychomotor skills, slower reaction times, poor communication, and periods of micro-sleeping.

HR Considerations

From an administrative point of view, 12-hour shifts require less time to implement and maintain. It is also easier to add hours to an experienced worker’s schedule than it is to hire, train, and provide benefits to a new employee (sometimes it takes years of training to get employees fully up to speed on their jobs).

When you consider that benefits account for 25% to 30% of each employee’s total compensation, fewer employees doing more (going from 8- or 10-hour shifts to 12-hour shifts) reduces total labor costs, minimizes mistakes and simplifies scheduling. Offering 12-hour shifts can also be an effective recruitment and retention tool.

Yet shift type and length also influence performance. The last part of a 12-hour shift tends to be the most mistake-prone. This can be especially dangerous in manufacturing environments. Studies vary, but there is enough evidence to suggest workers are more at risk to make mistakes that jeopardize their safety on 12-hour shifts.

The 12-hour shift is not necessarily cheered by all groups of employees, including older workers and female workers. Older workers are less likely to embrace 12-hour shifts, and may leave or retire, taking their experience with them.

My firm recently conducted a study of two years of workforce data over five years, looking for trends in 8- and 12-hour shifts. The finding? Twelve-hour shifts can dramatically reduce the female labor force.

The study revealed that an almost even percentage of men and women were on eight-hour temporary assignments in 2010 (51% male, 49% female). In 2014, after instituting rotating 12-hour shift calendars, data showed that the associate mix was 65% male and 35% female, a 28.6 percent decrease in the female demographic after switching to 12-hour shifts. This surprising result suggests that employers may be losing an important and productive part of their workforce by elongating the workday—most likely due to concerns about being home for their families. A longer shift not only impacts family life but limits available childcare options.

No Simple Answer

Which are better: eight-hour shifts or 12-hour shifts? Which shift length produces the greatest productivity? The fewest safety incidents? The highest worker satisfaction? The fewest health problems? There is no clear-cut winner. That’s why it’s important to consider the characteristics of each worker population during schedule selection. The best shift combination depends on the industry, operational variables and demographics of the local labor force.

The challenge with 12-hour shifts is to improve systems and develop practices that minimize the negative impacts of working 12-hour shifts. For example, be aware that working several consecutive 12-hour shifts increases the risk of injury due to increased fatigue. Twelve-hour shift workers often revert to a day schedule on their days off, which makes it difficult to re-adjust to the night-shift routine. To counter this, it is recommended that employees maintain their night-shift sleeping schedule during their days, in order to entrain their circadian rhythms to the work shift.

Ultimately, worker shifts must align with the company’s overall operational and workforce goals. For example, if safety is a big concern, 8-hour shifts may be best. For younger workers, who prefer three or four day weekends, a 12-hour shift can be a tempting incentive. Implementing 12-hour shifts does require extra HR time to educate, train, and follow up with 12-hour-shift workers.

Gogel is the implementation manager for staffing firm Operon Resource.