Fatigue Management

G lossary
circadian trough. A period, typically between 0200 and 0600 hours, where
body temperature is at its lowest level and mental performance, especially
alertness, is at its poorest.
circadian lull. A lesser circadian trough that typically occurs between 1300
and 1600 hours.
continuous operations. Recurring, round-the-clock schedules that last for
extended periods. Continuous Operations typically involve intense work
levels and use shifts and rotations.
fatigue. A state of weariness caused by physical and/or mental exertion.
fatigue management. A set of guidelines and procedures that attempt to
prevent and deal with the deteriorating performance, poor moods and lowered
willingness to work that are characteristic of chronic fatigue associated with
sleep loss.
insomnia. A sleep disorder characterised by difficulty falling asleep,
difficulty remaining asleep and/or waking earlier than intended.
jet lag. The ‘mismatch’ between local time and physiological cycles, and
between physiological cycles themselves, associated with travel to other time
zones.
micro-sleeps. Short lapses of sleep that may last a matter of a few seconds to
which the sleep deprived are prone.
nap. A sleep of duration less than three
hours.
nightmares. Dreams that cause awakening
in a state of fright or upset.
shift lag. The time-lag in physiological
readjustments, such as sleep onset, waking
and energy resources, which can lead to sleep
loss and fatigue usually caused by frequent
rotation of work schedules.
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