Fatigue Management

preclude effective combat performance. For instance, a soldier may be able to
fire at a fixed target but will not shoot effectively if targets appear randomly.
As a guide, general combat effectiveness can be maintained on three hours of
sleep per 24 hour period. Most soldiers can maintain an acceptable level of
physical performance for 9 - 14 days on such a schedule. However, extended
rest (at least three days) would then be necessary. Tasks that are mainly
mental in nature require more sleep. Table 6 gives guidance on the absolute
minimum amount of sleep required to maintain acceptable performance
levels in sustained operations where time is critical. This data is drawn from
British Army research. Remember that individuals will differ in their ability
to cope with sleep deprivation. Note that in NBC conditions, additional rest
periods are essential. (See pages 84-85 for further advice on recuperative
sleep.)
Table 6. Minimum Operational Sleep Requirements
Mainly Physical Tasks
Mainly Mental Tasks
Acceptable
performance
(days)
Sleep required
(uninterrupted )
Suggested
recovery
period
Acceptable
performance
(days)
Sleep required
(uninterrupted)
Suggested
recovery
period
3 0 24 hrs 1 0 8-12 hrs
6
1.5 hrs per
day
2 days 2 1.5 hrs per day 12-24 hrs
9 3 hrs per day 3 days 3 3 hrs per day 24 hrs
Work/Rest Schedules
The scheduling of work and sleep/rest periods is a key aspect of fatigue
prevention. Many work shifts used in the military appear to be adopted
without reference to the human dimension of operational performance.
Matters such as sleep need, the circadian cycle and the detrimental impact of
fatigue on performance are not considered when shift schedules are devised. It
appears that traditional shift schedules are rarely examined or questioned in
the military, and the performance detriments that some shifts generate either
go unnoticed, are ignored, or are accepted as unavoidable by-products of
continuous operations.
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