Rest Allowances - Fundamentals and Assessment Tools for Occupational Ergonomics - page 760

38.8.1 Guideline 1: Have a Work Scheduling Policy
The problem is insufficient rest. Two aspects are: (1) too many work hours and (2) work hours at the
wrong time.

38.8.1.1 Too Many Hours
Count all hours in “duty time.” For example, jobs such as train crews and flight crews often have waiting
and preparation time required before and after the “primary” job. There may be, especially for supervi-
sors, “shift turnover” time (people from the previous shift stay to communicate with the new shift).
People may work overtime when other individuals have to be replaced (illness, absenteeism). The
resulting shift can be 12 or even 16 h long. There probably should be some organizational restriction
on prolonged overtime (say over 12 h day and over 55 h week). Lack of sleep can increase if the individ-

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ual has a long commute time or moonlights.

38.8.1.2 Work Hours at the Wrong Time
Lack of sleep can result from sleeping at the “wrong time” or having irregular hours of work. Table 38.12
gives tips for day sleeping.

38.8.2 Guideline 2: Optimize Stimulation During Work
There may be too much stimulation (overload) or too little (boredom). Stimulation comes from both the
task and the environment.

. Too much stimulation. The usual solution is to reduce environmental stimulation. For example, for
office tasks, increase visual and auditory privacy
. Too little stimulation. Tasks are more stimulating if there is physical activity. Add variety within the
task or schedule a variety of tasks

Add environmental stimulation by (1) encouraging conversation with others (this may require two-
way radios for those who are physically isolated), (2) varying the auditory environment (talk radio,
stimulating music), (3) varying the visual environment (e.g., windows with a view), or (4) varying
the climate (change temperature, air velocity). Also consider chemicals such as caffeine.

TABLE 38.12 Tips for Day Sleeping

Develop a good sleeping environment (dark, quiet, cool, with a bed). Have it dark (e.g., opaque curtains). Have it quiet since
it is difficult to go back to sleep when daytime sleep is interrupted. Minimize changes in noise volume. Consider earplugs,
unplugging bedroom phones, turning down the phone volume in other rooms, reducing TV volume in other rooms, using
a fan to make noise. Train your children. Have the sleeping area cool. The bed normally is OK but may be poor if the sleeper
is not sleeping at home (e.g., is part of an “augmented crew” for trucks, aircraft). Then provide a good mattress and
enough space
Plan your sleeping time. Tell others your schedule (minimize interruptions). Consider sleeping in two periods (5 to 6 h
during the day and 1 to 2 h in the late evening before returning to work). Less daytime sleep and more late evening sleep
not only make it easier to sleep but also may give a better fit with family social activities. Night workers should go to sleep

as soon as they get home because the sooner they go to bed, the less adjustment their biological clock must make.
Have a light (not zero or heavy) meal before sleep. Avoid liquid consumption, as it increases the need to urinate (which wakes
you up). Avoid caffeine. A warm drink before your bedtime (perhaps with family members starting their day) may help
meet your social needs. Avoid foods that upset your stomach — and thus wake you up
If under emotional stress, relax before going to bed. One possibility is light exercise

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Source: Konz, S. and Johnson, S. 2004. Work Design: Occupational Ergonomics, 6th ed. Scottsdale, AZ: Holcomb-Hathaway.
With permission.