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May 8, 2000

6 Min Read
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Driven by an acute awareness of time, molders are compelled to squeeze every second of productivity out of a schedule. Process monitoring technology optimizes performance and shaves seconds off cycles while material handling systems and robots further accelerate production. Exhausting all other options, many molders in recent years have turned to unused nighttime and weekend hours to boost productivity. 

But while companies take careful steps with machinery to shift to 24/7 operations and maximize capacity, they often don't consider the physical and mental burden it places on workers (see Table 1). 

Heart problems, digestive disorders, immune system deficiencies, and higher-than-average divorce rates are just some of the issues workers may experience after the transition to a 24/7 routine, according to Bill Sirois, vp of Circadian Technologies Inc., a consulting firm that helps companies and employees transition to nonstop operations. Sirois says making the transformation is never easy. 

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Table 1. Human operator errors caused by inattention while working in a manufacturing plant by time of day



Battling Our Bodies 
"Since the beginning of time we grew up in nature following the sun," Sirois explains. "We're fighting biology that goes back to literally the beginning of human existence, and there's the rub." 

Sirois' company draws its name from the Latin words circa dia meaning "about a day." Devoted to the study of circadian rhythms, or those biological rhythms that cycle on 24-hour intervals, since 1983 the company has used its research to help workers adjust to the side effects of an unnatural 24/7 schedule. 

About 60 percent of its customers are companies that have implemented the dramatic change without proper planning and have seen negative results in the form of higher accident rates, increased turnover, and greater absenteeism. The other 40 percent are companies that want to undertake the necessary planning to make the transition as smooth as possible. Circadian's Marketing Manager David Mitchell says that, unfortunately, most companies don't operate with that much foresight. 

"Quite often the way it happens is it's a top-down decision," Mitchell says. "Management calls everyone together and says, 'Guess what? We're going 24/7,' and you can imagine the response when someone who's worked Monday through Friday for 20 years and always had weekends off is suddenly told that the very best he can do is get two out of four weekends off per month." 

Mitchell explains that workers can do worse, however, if their company adapts 8-hour shift work instead of changing to 12-hour shifts. Although there are hundreds of possible combinations, in one typical 8-hour shift scenario, employees work seven days on and two days off, seven evenings on and two days off, and finish up with seven nights on and three days off, giving them only one free weekend per month (see Table 2). 

TABLE 2. FOUR-WEEK ROTATING 8-HOUR SCHEDULE

 

Week 1

Week 2

Week 3

Week 4

 

VS. FOUR-WEEK ROTATING 12-HOUR SCHEDULE

 

Week 1

Week 2

Week 3

Week 4



Workers try to arrange their schedule so the three days off fall on the weekend, but they will still only get one weekend off per month. 

"If you're working 8-hour shifts, the very best weekends you can get is one out of four. There's no way to do it better on a typical 8-hour shift," Mitchell says. 

Despite the longer day, 12-hour shift work is more palatable to most workers. Typically called EOWEO (every other weekend off), this schedule has employees switching every two weeks from day and night shifts. They work two days on with two days off, three days on with two days off, and then two days on with three days off. This same schedule is mirrored for the second half of the month, but shifts switch from day to night. The schedule is arranged so the three-day breaks fall on the weekend and give employees an opportunity to recoup and spend time with family. 

Even with two out of every four weekends providing a brief respite from the grueling schedule, Sirois says shift work exacts a heavy physical and mental toll on those who undertake it. On average these workers only get 5 to 5.5 hours of sleep a night instead of the recommended 8-plus hours of sleep. A snowball effect ensues as the workers accrue interest on missed rest. 

"The sleep debt builds cumulatively," Sirois says. "It's like borrowing money from the bank--the sleep debt compounds. The bad news is you have to pay that debt back." 

Two nights of regular sleep repay the debt, but during the other nights, while working, shift employees are still quite strained. Sirois explains that the body operates differently at night, and companies need to make employees aware of these differences and prepare the workers. 

Core body temperature and blood pressure drop, hormonal secretions change, and digestive systems shut down. In addition, increased amounts of melatonin present in the brain induce sleep at the most inopportune times for shift workers. 

"Most shift workers will tell you that come 3, 4, 5 o'clock in the morning, they hit the wall," Sirois explains, "and they're just fighting sleep pressure to try to get through the back end of that shift." 

In fact, Sirois says, in the anonymous surveys his company performs at 24/7 operations, workers freely acknowledge dozing on the job. The consequences are obvious. 

"An operator on an injection molding press, at the rate at which we're spitting out product today, can generate a ton of scrap and rework if that operator's not on his toes," Sirois says. 

Attention to the Individual 
Molders forced to make the transition but eager to do it right have options, according to Sirois. He says every plant and each worker within that plant is unique and demands individual attention. Tailoring schedules to employee needs is a good first step. 

"Interview, survey, create criteria, and build schedules to meet those criteria," Sirois says. 

Apart from customizing the schedule to meet the specific needs of employees, other environmental factors can mitigate problems caused by shift work. Brighter lighting can trick the brain and fend off sleep, or music can provide added stimulus and keep workers more alert. Sirois says some companies have added workout rooms to give employees the option of exercise to ward off drowsiness. Other companies have added enclosed, darkened napping areas where employees can take brief catnaps to rejuvenate. 

These strategies can help alleviate the problem, but Sirois says the body has an intrinsic and inevitable reaction to the cycles of the sun. 

"Whether we're sleeping or not, whether we're working or not, whether we like it or not, Mother Nature is going to have her way with us," Sirois says. "It's a testimony to the men and women who work shift work in our country that our safety and productivity levels are as high as they are because those people are working under tremendous stress." 

Contact information
Circadian Technologies
Lexington, MA
Bill Sirois
(800) 284-5001
www.circadian.com

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