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Posted December 27, 2013
While insomnia, nightmares, and other sleep disorders are considered hallmark symptoms of posttraumatic stress disorder and some other mental health conditions, research has tended to view them as the result of the illness. Now researchers are beginning to explore which comes first, the mental illness or the sleep disorder.
Army Spc. Jevon Daurbigny takes advantage of downtime between events to catch up on some sleep during the 2012 Best Warrior Competition at Fort Benning, Ga. (U.S. Army photo by Ashley Cross)
A series of VA studies uncovering evidence tying sleep disorders to mental health issues in Veterans—not just as a symptom, but as a possible catalyst—signals a shift in research. Veterans with a history of sleep problems may be at greater risk for developing PTSD, depression, and other mental illnesses, according to the studies. One even found that a history of pre-deployment insomnia could be almost as significant as combat itself as risk factor for PTSD. The information could be useful in predicting, treating, and possibly even preventing the disorder.
One of the studies, led by investigators in the Minneapolis Veterans Affairs Health Care System, involved 172 Minnesota National Guard troops who deployed to Iraq from March 2006 to July 2007. The soldiers were part of larger research on National Guard readiness and resilience.
Participants completed surveys before and several months after their deployment. In addition, they completed a structured interview 6 to 12 months after returning from Iraq. Finally, they completed surveys one and two years after their return. The results were published in the Journal of Anxiety Disorders in June 2013.
Researchers discovered a strong correlation between soldiers who reported sleep problems prior to their deployment and subsequent mental health problems. "Daytime and nighttime sleep complaints contributed significantly to the prediction of diagnoses," wrote the authors of the study.
The research suggests that sleep allows the brain to process and store memories. Like a computer storing data, dreaming puts the memories into context for later use. The process, according to researchers, effectively decreases a memories' emotional charge. When sleep is disturbed, the brain can no longer function the same way. Traumatic events stay fresh in the mind, leading to anxiety disorders, depression, and PTSD.
"Sleep is thought to play a crucial role in helping to process and store emotional experiences from the day," says Dr. Melissa Polusny, of the Minneapolis VA, who worked on the study. "If people aren't sleeping well, they may be unable to tone down these memories and may be at risk for developing psychological disorders."
Another study, conducted by VA and Defense investigators at multiple sites and led by Dr. Philip Gehrman, an assistant professor of psychology at the University of Pennsylvania, yielded similar results. Gehrman found that the risk of PTSD for those with a history of insomnia was nearly as great as the risk of PTSD from being in combat. That study, published in the July 2013 issue of the journal SLEEP, involved 15,204 service members. Of those, 522 developed PTSD.
"We found that insomnia is both a symptom and a risk factor for mental illness," said Gehrman in a statement. "The potential exists for the designing and testing of preventative strategies that may reduce the occurrence of PTSD, anxiety, and depression."
Two similar studies conducted at the Durham (N.C). VA and the VA Greater Los Angeles Healthcare System yielded comparable results. The first, published in the July 2013 issue of Sleep, included 1,640 veterans of Afghanistan and Iraq. It concluded that sleep duration directly affected the odds of developing PTSD. Very short sleep duration—five hours or less per night—and long duration—nine hours or more—were both linked to higher odds for PTSD, depression, and smoking. The latter study, which focused only on women Veterans, found that of 107 women reporting insomnia, 55 percent also likely had PTSD. That study ran in the journal Behavioral Sleep Medicine.
Challenges remain, say the researchers. Because sleep disorders and mental health can be cyclical, it can be difficult to determine the root cause. Sleep problems increase mental illness risk but, the illness can then exasperate the sleep problem. Furthermore, because some Veterans may self-medicate with alcohol or drugs, the cycle can lead to substance abuse.
One study suggested the military incorporate sleep disorder screening into pre-deployment checklists. The idea, they say, would be to treat the sleep disorders before PTSD or other mental illnesses can take hold. "We have very effective psychological treatments to improve sleep," says Polunsy. "It is possible that improving sleep prior to exposure to stressful or potentially traumatic events could enhance soldiers' resilience. "