Combat Readiness
Sep 15, 2013

Many studies have proven that poor sleep negatively affects both physical proficiency and emotional well-being of the general population. Fatigue impairment has been proven to slow reaction time, decrease awareness and information retention, and impair judgment. As such, the sleep patterns of both serving military personnel and veterans should be of ­particular concern to those trying to help soldiers cope with the many stresses ­presented by military service.

From a worsening of vigilance to memory loss and depression, inadequate sleep comes at a high cost for soldiers and veterans. Fatigue and poor sleep complaints are common, not only among active-duty military personnel, but also veterans who are struggling with stress disorders.

Chronic Sleep Restriction
Chronically short sleep duration is frequently reported by deployed soldiers, and is associated with mood disorders (depression, panic and post-traumatic stress disorder), tobacco and alcohol abuse, and suicide attempts. Regular sleep deprivation can lead to increased stress levels and result in work inefficiency, aggressive behaviour and confusion.

A cross-sectional survey involving 3,152 members of a U.S. brigade combat team showed that 72% of soldiers slept six hours or less each night. Soldiers exposed to combat were more likely to report short sleep. Of course, active military combat can involve sustained sleep loss over several days, and in some cases may create disrupted sleep for the entire deployment.

Operating efficiently while in a sleep-deprived state is not something that can be “trained for”. New research from the University of Rochester Medical Center has proven that the body uses sleep time to flush waste that builds up in the brain during the day. By tracking dye in brains of mice, it was revealed that very little waste was removed from the brain during the wakened state, and that significant flushing occurs during sleep periods. Without enough sleep, it is believed that residual toxins and waste products can block or distort normal mental patterns.

While lack of sleep is not usually labeled as the biggest obstacle soldiers will face in combat, in training and in their post-duty lives, serious side effects have been documented in a number of studies.

  • Using a laboratory-based simulation of a sustained operations scenario involving continuous physical activity, sleep loss and food deprivation, investigators noted a decline in cognitive function (such as visual vigilance, choice reaction time and short-term memory) and worsening of mood.
  • A military training study looked at soldiers who only slept for an average of three hours each night while participating in an intense 53-hour training exercise. Lack of sleep was accompanied by significant weight loss and degradation in vigor, vigilance, attention, reaction time, reasoning and memory. Soldiers reported significantly increased fatigue, depression, tension and confusion.
  • In another study, designed to examine the effects of nutrition and activity on cognitive function during a four-day military exercise, soldiers demonstrated progressively worse cognitive impairment over the test period. After 24 hours, fatigue increased and vigor decreased, and after 48 hours, soldiers experienced feelings of depression, anger and confusion, as well as diminished vigilance and deteriorating delayed memory recall. Immediate memory recall was also affected by the second to third test day. Since there was no significant change in blood glucose concentration throughout the four-day study, the researchers concluded that the decline in cognitive function was more likely to be a consequence of significant lack of sleep.

There is a direct correlation between performance and degree of sleepiness. During total sleep deprivation, performance dips in all tests by 42 hours and continues to decline after 72 hours, with pronounced impairment in complex tasks involving cognition, precision and speed.

Obstructive Sleep Apnea
In addition to chronic sleep deprivation, sleep disorders – including obstructive sleep apnea (OSA) and sleep disturbances – also affect a high percentage of military personnel. A study investigating soldiers returning from combat who complained of sleep disturbances found that sleep disorders were present in 88% of those evaluated, including 63% with OSA and 64% with insomnia. More than one-third of soldiers had both OSA and insomnia, and this group was significantly more likely to suffer from depression and PTSD.

The high frequency of sleep disorders among active duty military personnel was confirmed by another U.S. study that reported prevalence of various sleep-related diagnoses, namely mild OSA (27%), moderate-to-severe OSA (24%), insomnia (25%), paradoxical insomnia – a misperception of short sleep without objective findings (5%), snoring (5%), and behaviorally-induced insufficient sleep syndrome (9%).

A large number (42%) of personnel reported habitually getting less than the recommended nightly sleep duration (less than five hours of sleep per night). Moderate-to-severe OSA was associated with anxiety, and insomnia was associated with PTSD and pain syndromes.
If left untreated, OSA can give rise to a wide-ranging number of adverse outcomes, including:

  • Excessive sleepiness
  • Insomnia
  • Hypertension
  • Ischemic heart disease
  • Heart failure
  • Cardiac rhythm irregularities
  • Stroke
  • Metabolic syndrome
  • Cognitive decline
  • Mood disorders

The first-line treatment for OSA for most patients is positive airway pressure (PAP) therapy. There are a number of different types of PAP devices, including:

  • CPAP: Continuous Positive Airway Pressure
  • APAP: Auto-titrating Positive Airway Pressure
  • BiPAP: Bi-level Positive Airway Pressure
  • Auto Servo ventilation

PAP devices pressurize the upper airway and act as a splint to keep the airway open during sleep. A patient uses a mask, commonly either a nasal or full-face design, that is attached to the PAP device via a flexible tube. To achieve the best effects, patients should use their PAP device every night.

Some clinicians have expressed concerns that adherence to nightly CPAP therapy might be lower among soldiers with combat-related PTSD. One report indicated that PTSD was associated with significantly less use of CPAP, both in the percentage of nights during which CPAP is used as well as in the hour of use each night. Soldiers with PTSD also tended to use CPAP less regularly. When consistent use is maintained, positive results are reported, therefore it may be helpful to ­discuss with a doctor any barriers related to the use of such devices.

Given the high prevalence, severity and diversity of side effects associated with poor sleep among military personnel, it is essential to discuss sleep disturbance or persistent daytime sleepiness or fatigue with your primary care clinician or sleep specialist. Your physician will obtain a thorough sleep and medical history, and may ask you to keep a sleep diary for several days.

A number of tests may be performed to identify the causes of poor sleep quality, including polysomnography (laboratory-based sleep test for OSA), home sleep apnea test, actigraphy (a device generally worn on the wrist for several days that assesses periods of sleep and wakefulness), and procedures to determine the presence and severity of daytime sleepiness. Neurologic and psychiatric evaluations may also be indicated for some individuals.

Effective treatments are available for many sleep disorders, including OSA, insomnia, excessive sleepiness, and restless legs syndrome. Addressing these disorders can significantly improve the quality of life experienced by both active duty and ­veteran military personnel.
Teofilo L. Lee-Chiong Jr., MD is a Professor of Medicine at National Jewish Health in Denver and at the University of Colorado Denver School of Medicine. He joined Philips Respironics as Chief Medical Liaison in 2011.
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