Safer Shift Work through More Effective Scheduling
Sleep patterns, rest breaks, 'mini-vacations,' are all part of the equation.
- By George Brogmus, Wayne Maynard
- Dec 01, 2006
SO many industries utilize shift
work schedules that nearly 15 million full-time workers in the United States
work shifts outside the traditional 9-to-5 or flextime workday, according to
the Bureau of Labor Statistics. Yet those added shifts, implemented
specifically to increase profitability, may actually be costing companies money
through higher worker injury rates. By rethinking how you schedule shift work,
you can help keep workers safe and make each shift more effective.
Based on the findings of a recently
published Liberty Mutual Research Institute study modeling the impact of the
components of long work hours on injuries and accidents, the loss prevention group
developed a program to assess worker injury risk based on work scheduling
factors such as time of day, hours per shift, number of consecutive shifts, and
time between rest breaks. The program addresses the following shift work
injuries increased 15.2 percent on afternoon shifts and 27.9 percent on the
night shift relative to the morning shift.
- Injury risk increases
nearly linearly after the eighth hour of a shift, with risk increasing 13
percent on a 10-hour shift and almost 30 percent on a 12-hour shift.
- As consecutive
shifts increase, injury risk also increases, but at a higher rate for night
shifts than for day shifts:
**Average risk for
injury is 36 percent higher on the last night of a four-consecutive-nights
shift. Risk increases incrementally over each night on the job: 6 percent
higher on the second night, 17 percent higher on the third night, culminating
at 36 percent on the fourth night.
**Injury risk is 2
percent higher on the second morning/day shift, 7 percent higher on the third
day, and 17 percent higher on the fourth day than it is on the first shift.
- Injury risk also
increases as time between breaks increases. The last 30 minutes of a two-hour
work period has twice the risk of injury of the 30 minutes immediately after
One way to combat these
problems is to evaluate the combined effect of work scheduling factors rather
than to just limit total work hours. For example, scheduling four 12-hour day
shifts with hourly breaks will produce less risk than six eight-hour night shifts
with hourly breaks. Both shift schedules add eight hours of work, but only one
has significantly less risk of injury.
If you are contemplating
adding overtime or expanding shifts, consider the following guidelines to help
build a safer shift work schedule. Tips for general shift work:
- Establish maximum
limits for days and nights worked per week, including overtime.
- Favor day/morning
shifts over afternoon or night shifts.
- Consider adding
hours to existing shifts or add an additional day of work to the project.
- Limit work to
five or six consecutive shifts.
- Provide for
frequent rest breaks. Hourly breaks are generally appropriate, but consider
providing more frequent breaks for highly repetitive or strenuous work.
- Schedule work so
every worker has at least two consecutive rest days and that at least one of
these days is Saturday or Sunday.
- Avoid scheduling
several days of work followed by four- to seven-day mini-vacations. These
schedules should be used only when there is no other choice (such as in mining
or oil exploration).
- Keep schedules
regular and predictable.
- Alternate weeks
of overtime with weeks of normal time.
Get Workers Involved
For those situations when you
have to schedule night shifts, here are some ways to help combat the increased
risk of injury:
- Keep consecutive
nights shifts to a minimum: Four nights maximum in a row should be worked
before a couple of days off, and schedule no more than 48 hours of night shift
work per worker per week.
- Educate workers
on the importance of getting enough good sleep. Suggest they use blackout
drapes, turn off phone and pagers, and use a fan or white noise to mask daytime
noises. Regular exercise, diet, and relaxation techniques are also effective
strategies for coping with night work.
alternatives to adopting permanent night shifts. Most workers never fully adapt
to night shift work because they go back to a daytime schedule during days off.
- Avoid quick shift
changes, and adjust shift length to the workload.
- Take into account
all aspects of workers' jobs and home lives when changing work schedules.
When scheduling shift
rotation, provide a minimum of 11 hours off between shifts and a minimum of
24-48 hours when rotating workers off the night shift. Ideally, the change from
the night and morning shifts should happen between 7 a.m. and 9 a.m. because starting
the morning shift too early often cuts down on evening sleep time. Also, keep
in mind that forward shift rotation--going from a day to afternoon, or
afternoon to night, or night to day shift--is more compatible with normal sleep
patterns than backward shift rotation.
Whatever approach you take to
scheduling shift work, a very important component is worker involvement. You
should solicit worker feedback in the scheduling process rather than handing
down a mandatory schedule. And provide training or awareness programs for new
shift workers and their families to help them cope with the irregular schedule.
Lastly, ensure that workers on all shifts, including the non-traditional
schedules, have access to health care and counseling services.
With 15 percent of the total
workforce working non-traditional shifts, rethinking shift scheduling can make
a significant impact on productivity and worker safety.
This column appeared in the December 2006 issue of Occupational Health & Safety.
This article originally appeared in the December 2006 issue of Occupational Health & Safety.