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July 16, 2021
Management of Sleep and Fatigue in Military Aviation
In recent years, Congress has expressed concern over the
sleep environments, operational demands, unpredictable
effects of sleep deprivation on servicemember health and
schedules, long-duty days or flight durations, challenging
military readiness, as well as its impact on military aviation
flight conditions, and circadian-rhythm disruption due to
safety. Aviators in all military services of the Department of
crossing multiple time zones, known as chronodisruption.
Defense (DOD) with high operational demands and austere
In a March 2021 report to Congress, DOD stated sleep
work settings may experience sleep deprivation and fatigue.
deprivation has “significant effects on the physical,
To counter these effects, the military services use a variety
cognitive, and emotional functioning needed for readiness,
of mitigation strategies (i.e., non-pharmacological and
occupational, and operational mission fulfillment.” The
pharmacological measures) to enhance aviator safety and
report also described the “risk of accident in training,
prevent aviation mishaps. This In Focus provides an
operational, and combat environments significantly
overview of those mitigation strategies and offers issues for
increases if Service members are sleep deprived.”
congressional consideration.
Fatigue Management in Military Aviation
Background
Each military service is responsible for implementing its
The U.S. Centers for Disease Control and Prevention
own policies and procedures to mitigate aviator fatigue and
estimates 32.5% of adults do not meet the Healthy People
sleep deprivation. The military services use varied
2020 (HP2020) criteria for sufficient sleep. In comparison,
approaches to mitigate aviator fatigue, including: (1)
the 2018 DOD Health Related Behaviors Survey estimated
administrative and behavioral (i.e., non-pharmacological)
54.6% of active duty servicemembers did not meet HP2020
measures, and (2) the voluntary use of pharmacological
criteria. HP2020 categorizes sufficient sleep as at least
measures. Regulations for each service consistently
seven hours in a 24-hour period. Research indicates a
emphasize non-pharmacological measures as the primary
variety of detrimental health effects arise from both acute
means of mitigating fatigue.
and chronic sleep deprivation.
Administrative and Behavioral Measures
Administrative and behavioral measures can include limits
Sleep deprivation and fatigue are two distinct physiological
on the length of an aviator’s duty day, or time spent flying,
states. The National Institutes of Health defines sleep
and standards for rest and time available for sleep. The
deprivation as a condition that occurs when someone “[does
military services also educate aviators on the impact of
not] get enough sleep.” Sleep deprivation is a contributor to
sleep loss and the benefits of consistent sleep.
fatigue. The National Institute for Occupational Safety and
Health defines fatigue as a “feeling of weariness, tiredness
Pharmacological Measures
or lack of energy.” Sleep deprivation and fatigue can be
Historical Use of Pharmacological Measures. The U.S.
most apparent when an individual is awake counter to their
military historically has approved pharmacological
circadian rhythm (i.e., during the circadian trough of
measures for aviators in certain mission contexts. For
alertness), typically apparent during the early morning
example, the Air Force and Navy have authorized the use of
hours (see Figure 1).
pharmacological measures for select missions and aircrew
during combat operations, at least since the Vietnam War.
Figure 1. Relative Level of Alertness and Wakefulness
The operational needs for these measures have been
Based on Time of Day
scrutinized and are an area of review. For example, the Air
Force suspended the use of stimulants between 1996 and
2001. After considering survey results from pilots flying
during Operation Desert Storm and four placebo-controlled
studies, the Air Force validated the need and utility of the
measures and rescinded the suspension.
Current Use. Longer flight durations, continuous
operations, improvements in night-vision technology and
the combat advantage of night operations have led to a
greater potential for fatigue and operating during a pilot’s
circadian trough, increasing the need for pharmacological
measures. The military services authorize aviation medicine
Source: CRS, Derived from Shappell, et al., Crew Rest and Duty
specialists (i.e., flight surgeons) to prescribe U.S. Food and
Restrictions for Commercial Space Flight, available at
Drug Administration (FDA)-approved pharmacological
https://rosap.ntl.bts.gov/view/dot/34244
agents as a fatigue management measure when
Military aviators may experience sleep deprivation and
administrative and behavioral measures are known or
fatigue due to a variety of factors, including inhospitable
expected to be insufficient. No DOD-wide policy
https://crsreports.congress.gov
Management of Sleep and Fatigue in Military Aviation
standardizes the situations or conditions for use of
Aeromedical Policy Letter on Pre-deployment Rest or
pharmacological measures. Each military service sets its
Sustained Operations Agents authorizes prescription
own policies for which aviators may use pharmacological
stimulants for aviators. However, some communities, like
measures and under which conditions. The services are all
special operations aviators, likely use them more than
similar in limiting pharmacological measures to specific
others. The Air Force delegates authority for stimulant use
operational circumstances, establishing a process by which
to its Major Commands. In turn, Air Force Major
authorization for use is conducted (e.g., in both medical and
Commands restrict stimulant prescriptions to fighter,
command channels), limiting the amounts prescribed and
bomber, and certain reconnaissance aircraft pilots.
duration of use, and monitoring use by flight surgeons. In
Sedative-hypnotics. Typically, a flight surgeon may
all services, use of pharmacological measures by aviators is
prescribe sedative-hypnotics, commonly called no-go pills,
voluntary. Figure 2 lists the pharmacological agents used in
for limited periods and with commander approval, to aid in
fatigue management.
sleep initiation when an operational need exists. Situations
might include inhospitable sleep settings, the need to shift
Figure 2. Pharmacological Agents Authorized for
sleep schedules, or crossing multiple time zones. In a 2021
Fatigue Management in Aviators and Aircrews
report to Congress, DOD cautioned sedative-hypnotics have
a “wide range of side effects” that can impact readiness.
Some side effects include drowsiness, disinhibition,
impaired cognition, learning deficits, and increased risk of
vehicle accidents. To mitigate some effects, regulations
prohibit aviators from flying for specific periods of time
after ingesting, based on drug type. Flight surgeons must
monitor aviators’ use of the drugs and level of fatigue.
Federal Aviation Administration (FAA)
Management of Fatigue
Similar to the services’ non-pharmacological measures,
FAA regulations stipulate a variety of fatigue mitigation
regulations for pilots conducting commercial flights. Some
measures include maximum duty time, rest requirements,
and number of consecutive nights of flying. FAA
regulations do not permit the use of stimulants. However,
FAA-certified medical examiners may authorize sedative-
Source: CRS graphic based on DOD’s “Study on Effects of Sleep
hypnotics (including some not authorized by DOD) and
Deprivation on Readiness of Members of the Armed Forces,” and
melatonin supplements for occasional or limited use by
analysis of FDA drug data at
civilian pilots.
http://www.accessdata.fda.gov/scripts/cder/daf.
Questions for Congress
Notes: *Typical y experienced with doses higher than those used by
The following lines of inquiry may assist Congress in
the services. **When used at prescribed doses. All refers to al
considering military aviation safety and support
services in DOD, except the U.S. Space Force. The FDA defines
congressional oversight of DOD programs and initiatives to
abuse as the intentional, non-therapeutic use of a drug to achieve a
prevent sleep deprivation and fatigue.
desired psychological or physiological effect. Dependence refers to a
physical or psychological dependence where individuals experience
Impacts to Military Operations and Readiness
symptoms of withdrawal or have impaired control over drug use.
What lessons-learned from non-pharmacological or
Stimulants. Flight surgeons may prescribe stimulants,
pharmacological measures in aviation can be applied to
commonly called go-pills, to counter fatigue and improve
other military occupations (e.g., naval vessel crew,
alertness and performance, but must issue limited
medical personnel, special operations)?
quantities, monitor aviators, and collect unused
Should the use of pharmacological measures remain
medications. Use of stimulants requires authorization by the
voluntary, or be mandatory under certain conditions?
prescribing flight surgeon and the medical chain of
How do authorized pharmacological measures affect the
command and, at a minimum, a colonel/Navy captain/O-6
risk for substance use or abuse among aviators?
in the aviation unit’s chain of command. Military services’
policies authorize selected aviators to use
Effectiveness of Fatigue Management Strategies
dextroamphetamine. The FDA classifies this stimulant as
having a “high potential for abuse” and
What scientific consensus exists regarding the
prolonged use “may
lead to drug dependence.”
effectiveness of current methods to prevent or mitigate
Air Force policy also allows the
fatigue and sleep deprivation in DOD aviators?
use of the non-amphetamine-based stimulant, modafinil.
What DOD efforts are in progress to identify novel or
The FDA recommends observation for “signs of misuse or
abuse,” and notes
emerging fatigue management strategies?
modafinil can produce “psychoactive and
euphoric effects…
What impact would arise from creating a DOD-wide
and feelings typical of other [central
nervous] stimulants.”
policy on fatigue management strategies in aviation?
The military services’ policies differ by authorizing which
Christian Bergtholdt, U.S. Air Force Fellow
aviators may receive stimulants. For example, a 2003 Army
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Management of Sleep and Fatigue in Military Aviation
IF11881
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