Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 8
8
Local night routes and cross-country routes often involve SLEEP DISRUPTION
nighttime driving and daytime sleeping. Night drivers com-
monly shift to daytime schedules on weekends or days off, Interruptions to or disturbed sleep can make returning to
resulting in weekly disruption of their usual sleeping period. sleep more difficult. It has been shown that both the number
HOS rules can require an off-duty period that is not conducive and timing of disruptions can adversely affect daytime alert-
to sleep (e.g., 4 p.m. to 2 a.m.), resulting in low-quality sleep ness. Some general factors that disrupt sleep in commercial
immediately followed by a driving period beginning during transportation operations include
a "low" circadian period (i.e., 2 a.m.).
· Noise, vibration, movement, uncomfortable temperature,
and poor air quality in sleeping quarters;
Changing or Rotating Work Schedules · Unfamiliar environments away from home with less than
optimal conditions; and
Many commercial transportation operations require fre- · Attempting to sleep at an inappropriate time for one's
quent changes or rotations in schedule. These schedule shifts circadian rhythm.
lead to relatively quick changes in the time of day at which
operators can obtain sleep, generally resulting in inadequate INADEQUATE EXERCISE OPPORTUNITIES
levels of rest. Changing or rotating work schedules can be
characterized as follows: People who exercise regularly have fewer episodes of sleep-
lessness. Isolated exercise, while not an effective countermea-
· Changes in work and rest schedules that do not have a sure for immediate fatigue, can improve sleep quality by
fixed pattern and thereby result in fatigue management promoting smoother, more-regular transitions between the
challenges that are extremely difficult to address, and cycles and phases of sleep. Moderate exercise lasting 20 to 30
· Rotating schedules that have fairly systematic shifts in minutes, three or four times a week, promotes sleep. Exercise
the work start and stop times. in the morning or afternoon is preferred, because exercise close
to evening bedtime can disrupt the onset of sleep. A brisk walk
can be very beneficial, although more vigorous exercise has
Unpredictable Work Schedules been shown to provide increased health benefits. Even exer-
cises designed for environments with restricted space (e.g.,
The amount of advance notice commercial transportation inside a truck sleeper berth) have also been shown to be bene-
operators receive regarding their work schedule varies sub- ficial. Factors that may limit exercise opportunities include
stantially. An unpredictable schedule can lead to forced
changes in sleep times and therefore to low-quality sleep. · Personal habits that might need to be overcome in initi-
Unpredictable schedules can also cause workers to wake ating an exercise program,
sooner than necessary in order to check in with dispatchers. · Work schedules that might need to be adjusted to
Conditions commonly associated with unpredictable work include appropriate exercise opportunities, and
schedules include · Travel or living conditions that can limit access to exer-
cise equipment or space.
· Being "on call" for work without a fixed schedule;
· First-in, first-out work pool scheduling; and POOR DIET
· Schedule delays resulting from equipment, weather, or
traffic problems. What one eats can be a determining factor in sleep quality
and duration. Some dietary behaviors that can disrupt sleep
include
LACK OF REST OR NAP
PERIODS DURING WORK · Eating heavy or spicy foods just prior to bedtime, which
can interfere with sleep by causing heartburn;
Taking a brief rest or nap during a work period is a con- · Consuming alcohol just prior to bedtime can induce
troversial topic in some transportation settings, while it is sleep initially, but tends to lead to fragmented sleep; and
considered the procedural norm in others. Research has demon- · Consuming caffeine within 4 to 6 hours before bedtime
strated the value of planned napping to supplement main can delay the onset of sleep as well as disrupt sleep.
sleep obtained and to temporarily restore alertness on the job.
Lack of rest or nap periods can result from ENVIRONMENTAL STRESSORS
· Company policies that restrict or prohibit napping, and Several environmental factors can adversely affect a com-
· Unwillingness of operators to take naps. mercial transportation operator's level of alertness. These
OCR for page 9
9
include environmental aspects related to heat, humidity, cold, Drivers should be aware of the effects of high altitude,
altitude, vibration, and noise. and, if at all possible, should avoid sleeping at high altitudes
(e.g., above 5,000 feet).
Heat and Humidity
Whole Body Vibration
Generally, one experiences high ambient temperatures as
dry heat (temperature above 85°F, humidity less than 50%) or Whole-body vibration and acceleration accompany opera-
wet heat (temperature above 85°F, humidity above 80%). All tion of several types of transportation vehicles, including air-
excessively hot conditions make operators feel less alert and craft, helicopters, large trucks, buses, trains, ships, and small
generally more fatigued. Hot-wet working conditions can be vessels. Operation of helicopters, automobiles, trucks, and
significantly more detrimental to worker performance than can buses exposes operators to increasing acceleration magnitudes,
hot-dry conditions and will usually make one feel "fatigued" with a frequency range extending up to 100 Hz, depending on
much sooner than will temperatures less than 75°F. the roughness of the air/road/seas and the vehicle speed.
Although most operators consider these to be lower-level
Cold fatiguing effects, they can add to operators' general feeling
of fatigue, thereby compromising their alertness while oper-
Cold weather can indirectly contribute to operator fatigue. ating equipment, especially if they are exposed to these effects
Operators often wear several layers of clothing during cold over long duty days.
weather, which can make using restroom facilities more dif-
ficult, which in turn can lead operators to reduce the amount
Acoustical Noise
of liquids they consume. Reduced liquid consumption can
then lead to dehydration, which can cause operators to Operators are exposed to engine noises in all transportation
become fatigued more quickly than usual. vehicles, as well as related noises emanating from controls,
transmissions, braking systems, and wind streams. Some of
High Terrestrial Altitude these noises present more of a hearing-conservation issue than
a driver fatigue issue. In fact, wearing ear protection in the
Driving at altitudes in excess of 5,000 feet can increase a presence of these noises is often called for; however, these
driver's respiration and heart rate; and sleeping at high altitude noises can also contribute to an operator's level of fatigue. The
can result in blood pooling in the arms and legs. Spending continuous "hum" and other intermittent noises of most run-
even a few hours at high terrestrial altitude (e.g., mountainous ning engines, especially in hot and stuffy crew compartments,
passes) can cause the general malaise and discomfort that can contribute to sleepiness on lengthy trips. Being aware that
accompanies Acute Mountain Sickness (AMS). These effects noise can contribute to one's overall feeling of operator
dissipate as one acclimates to a higher altitude, usually in a fatigue is an important step toward ensuring that operators
matter of a few days. take rest breaks.
