What to Know About Sleep Deficiency

LAST UPDATED: April 27, 2021
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Our brains cannot function without sleep. You can't train your brain to do more with less sleep and there are no shortcuts, not even consuming more caffeine. The brain only works as well as the amount of sleep it obtains. Remember, "Sleep is ammo for your brain." The more you get, the more mentally sharp you will be. 

Purposely going without adequate sleep

Purposely going without enough sleep is sometimes considered a sign of strength (and needing sleep a sign of weakness).  This is nonsense.  Going without sleep is no more a sign of strength than going without water or air.  When you don't get enough sleep there is a tendency to become irritable, distracted, and stressed more easily. The ability to perform your mission, do well at school, work, or home improves as you get more sleep.  As sleep duration increases, so does productivity, energy, efficiency, and mental sharpness.  

Problems getting to sleep or staying asleep (Insomnia)

Problems initiating and/or maintaining sleep are among the most common complaints of Soldiers, especially those who have recently returned from deployment. From 2000 to 2009, the diagnosis of insomnia in active duty Army personnel increased 19-fold. This is important because insomnia is associated with anxiety, depression, PTSD, chronic pain, alcohol abuse, and even with suicide.

We all have been that person who did not get enough sleep the night before. You tend to look tired, be a bit grumpy, and consume your caffeinated beverage of choice to "get going" and to "make it through the day." When we fail to get adequate sleep we are less likely to make healthy food choices, we feel less motivated, and we are less active and productive.

Signs of inadequate sleep

The best way to evaluate an individual's status is to observe his or her behavior. Indications of inadequate sleep include:

  • Struggling to stay awake during briefings, classes, etc.
  • Difficulty understanding or tracking information
  • Lapses in attention (mind "wandering")
  • Decreased initiative or motivation
  • Irritability

Or, ask the obvious question: "How much sleep have I had over the last 24 hours?" Leaders should also ask themselves this question.

Consequences of sleep deficiency

Common short-term consequences of sleep deficiency include:

  1. Decreased physical and mental performance
  2. Impaired memory
  3. Impaired concentration
  4. Longer reaction time
  5. Poor decision-making
  6. Decreased testosterone production
  7. Diminished emotional control

Over the long term, insufficient sleep has been linked to increased risk for developing several medical conditions such as obesity, diabetes, hypertension, cardiovascular disease, some cancers and Alzheimer's disease.

Insufficient sleep also impairs one's ability to self-monitor. Sleep-deprived individuals – both Soldiers and leaders – invariably overestimate their ability to function, and think that they are performing better than they actually are.  Again, this is because the ability to self-monitor is itself dependent on adequate sleep. The physiologic deficits that result from inadequate sleep cannot be overcome by motivation, initiative, or willpower—and they can only be TEMPORARILY masked, and only to a limited extent, by caffeine.

Sleep, performance and safety

The "adrenaline rush" experienced during combat or training does not offset insufficient sleep. A sleep deprived Soldier might shoot a "friendly," enter the wrong coordinates, or give the wrong dose of medicine. In general, sleep-deprived Soldiers have a higher potential to make unwise tactical decisions that could lead to catastrophic outcomes. For these reasons, and for all of the other reasons discussed to this point, leaders should prioritize sleep for their Soldiers AND themselves.

Soldiers who consistently obtain fewer than 7 hours of sleep per night perform much like a person who is legally drunk. They lose their situational awareness, lose the ability to exercise good judgment and engage in risky behaviors. They also are at risk of uncontrollably and unintentionally falling asleep  during critical activities such as driving, conversing, and monitoring equipment. Put simply, accidents increase as the total amount of sleep you get each night decreases.

Common combat tasks compromised by insufficient sleep

These include (but are not limited to):

  • Requesting indirect fire
  • Detecting and appropriately determining threat level
  • Coordinating squad tactics
  • Combat activity such as firing from bounding vehicle and observing the terrain for enemy presence 

Drowsy driving

According to the National Highway Traffic Safety Administration (NHTSA), fatigue-related crashes are the leading cause of "fatal to the driver" truck crashes. According to the Center for Disease Control (CDC), approximately 25% of motor vehicle accidents are related to drowsy driving.

The total number of crashes attributed to sleepiness are equal to the number of drug and alcohol related crashes combined. This means that drowsiness is the principal cause in at least 100,000 police reported traffic crashes each year, killing more than 1,500 Americans and injuring another 71,000.

In one survey, adults who reported unintentionally falling asleep during the day were more likely to fall asleep when driving, to snore, and to sleep 6 or fewer hours per 24 hour period. The most common drowsy drivers are men, young drivers, binge drinkers, and people who rarely or never wear seatbelts. Adults between 18–24 years old are more likely to drive drowsy than any other age group and have the highest rate of fatal drowsy driving-related accidents.

Based on safety data collected by the Army from FY 11 until August of 2014, 569 Soldiers were killed or injured in accidents attributed to fatigue. The emotional cost of these fatigue-related accidents is huge and the dollar estimate is approximately $3.5M . This is almost half of the cost of all accidents in the Army during the same timeframe.

Sleep debt and performance

The demanding nature of military operations often creates situations in which obtaining enough sleep on a regular basis is difficult or impossible. Such chronic, insufficient sleep (anything less than 7 hours per 24 hours) produces a sleep debt—a chronic state of sleep need characterized by impaired performance and reduced readiness. The rate at which the sleep debt (and performance deficits) grows depends upon the extent to which nightly sleep is restricted relative to how much sleep an individual needs. The only way to eliminate sleep debt is to get more sleep.

How much sleep do I need?

To determine how much sleep you need, you must have at least one "free" week in which there are no restrictions on the amount of time that you are able to remain in bed (such as during a vacation with no family obligations and responsibilities). During this week, do the following:

  1. Go to bed at the same time each night, and sleep until you feel rested and restored.  As you pay off your sleep debt, the amount of sleep that you obtain will decrease across nights. 
  2. Repeat this until you spontaneously (without an alarm) awaken at the same time each day, for three consecutive days. The amount of sleep that you obtained on these three nights is the amount of sleep that you need to maintain optimal alertness.
  3. Once you know how many hours you need, begin to establish a sleep routine with the same sleep and wake times that allows for this amount of sleep.
  4. Ensure you practice good sleep habits (see Bedtime Routine).

By the way, if you already awaken without an alarm clock, and get up at the same time each day regardless of whether or not it is a work or duty day: Congratulations! You are probably already getting adequate sleep on a regular basis.

Sleep debt

A sleep debt occurs when you get less sleep than you need. You can recover from sleep loss by going to bed a little earlier each night and/or staying in bed longer each morning. It is impossible to train your brain to function better with less sleep. There are no alternatives to sleep. Your brain only works as well as the amount of sleep you obtain; the more sleep you get, the more mentally sharp you are. You cannot recover sleep lost as a result of chronic sleep deficiency in only one or two nights. The best recommendation for someone in this situation is to get as much sleep possible for as long as possible. This will result in gradually improved mental sharpness, energy, performance, and general health. 

Performance decrement across days of insufficient sleep

The following figure shows the relationship between hours of sleep per night and performance for the average adult. As shown, anything less than 7 hours of good-quality sleep per 24 hours negatively impacts performance—and impairment worsens as nightly sleep duration decreases.

Performance decrement measured in percent of normal cognitive performance

5 days/8 hours sleep = 100% performance, 6.5 hours = 90%, 5 hours = 80%, 3 hours or 2 days of no sleep = 70%

With 7+  hours of sleep per 24 hours, Soldiers sustain optimal performance for the entire waking day (Green zone).

When Soldiers get less than 7 hours of sleep, performance degrades over time. Getting 4–6 hours of sleep every 24 hours will keep Soldiers in the Amber zone (90% to 85% performance) for several days, then they fall into the Red zone (85% to 50% performance). Getting less than 4 hours of sleep guarantees that Soldiers immediately fall into the Amber Zone and quickly progress into the Red Zone.

Less than 5% of Soldiers can sustain performance reasonably well on less than 7 hours sleep per 24 hours. If a Leader is in this 5% group, it may be difficult for him or her to understand that most Soldiers require more sleep than they do—and to foster a unit environment where 7+ hours of sleep per night is recognized as normal and encouraged.


The CDC, the American Academy of Sleep Medicine, the Sleep Research Society, and the National Sleep Foundation (NSF) each recommend that adults consistently obtain no fewer than 7 hours of sleep per night (CDC, 2017c; NSF, 2018). In 2017, most AC Soldiers reported getting 6 or more hours of sleep per night on both duty and non-duty nights.

Table 1. Estimated Hours of Sleep by Duty Status, AC Soldiers, 2017

Most Soldiers report sleeping 6 to 7 hours per night, regardless of duty status. However, nearly 1 in 3 report getting less than 6 hours of sleep on weeknights/duty nights. Soldiers also report getting more sleep on weekend/non-duty nights than on weeknights/duty nights.

Table 2. Percent of Soldiers Meeting Weeknight/Duty Night Sleep Target by Sex and Age, AC Soldiers, 2017

Regardless of sex or age, only about 1 in 3 AC Soldiers attained the minimum target of 7 or more hours of sleep on weeknights/duty nights.

Table 3. Percent of Soldiers Meeting Weekend/Non-Duty Night Sleep Target by Sex and Age, AC Soldiers, 2017

In contrast, nearly 3 out of 4 AC Soldiers met the minimum sleep target on weekends/non-duty nights. The trend of increased hours of sleep on non-duty nights was similar across sex and age groups – and reflects the brain's attempt to pay off a sleep debt.


Army leadership should prioritize weekday sleep for all Soldiers to enable Soldiers to achieve optimal performance and readiness goals.

Percent Meeting SAN Targets, AC Soldiers, 2017:

Sleep on weeknights/duty nights: 
38% obtained 7 or more hours of sleep on weeknights/duty nights.

Sleep on weekends/non-duty nights: 
72% obtained 7 or more hours of sleep on weekends/non-duty nights.

Performance Triad Measures by Installation

Performance Triad Measures by Installation

 Table 4. U.S.-based Installations
Installation7+ hours of sleep [weeknight/ duty night] (%)7+ hours of sleep [weekend/ non-duty night] (%)2+ days per week of resistance training (%)150+ minutes per week of aerobic activity (%)2+ servings of fruits per day (%)2+ servings of vegetables per day (%)
Fort Belvoir43
Fort Benning376784894753
Fort Bliss397183903442
Fort Bragg397585903646
Fort Campbell437485913342
Fort Carson407283903340
Fort Drum407584903240
Fort Gordon357580893848
Fort Hood357082893341
Fort Huachuca387983924248
Fort Irwin397180883340
Fort Jackson265482935962
Fort Knox437581903747
Fort Leavenworth487681883850
Fort Lee347481914044
Fort Leonard Wood377083924754
Fort Meade447782893648
Fort Polk397483903139
Fort Riley387484913341
Fort Rucker537882893649
Fort Sill367383913746
Fort Stewart367284903239
Fort Wainwright367383893039
JB Elemendorf- Richardson387688913544
JB Langley-Eustis407281903644
JB Myer-Henderson Hall397885903848
JB San Antonio357578874151
Presidio of Monterey478683934864
USAG West Point498177884345
Table 5. Installations Outside the U.S.
Installation7+ hours of sleep [weeknight/ duty night] (%)7+ hours of sleep [weekend/ non-duty night] (%)2+ days per week of resistance training (%)150+ minutes per week of aerobic activity (%)2+ servings of fruits per day (%)2+ servings of vegetables per day (%)
USAG Bavaria367283903240
USAG Rheinland Pfalz36738087
USAG Stuttgart427581893745
USAG Vicenza377786923544
USAG Wiesbaden387380873345
USAG Daegu377383923140
USAG Humphreys407583903340
USAG Red Cloud367385913037
USAG Yongsan417482883341
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