(Reuters Health) - Soldiers who have insomnia before deployment may be more likely to develop post-traumatic stress disorder (PTSD) or experience suicidal thoughts than service members who don’t struggle to sleep before they deploy, a U.S. study suggests.

For the study, researchers surveyed U.S. Army soldiers one to two months before they deployed to Afghanistan in 2012, right after they returned from deployment, and again three months and nine months later.

Overall, 21 percent of the soldiers had experienced insomnia at some point prior to deployment and 15 percent had insomnia within the 30 days before deployment.

Soldiers who experienced insomnia in the 30 days prior to deployment were more than three times more likely to experience PTSD and more than twice as likely to have suicidal thoughts after their return than peers who didn’t have sleep difficulties at the start of the study.

“This raises the possibility that if insomnia were successfully treated before soldiers deployed their risk of developing PTSD or suicidal thoughts might be lower,” said lead study author Dr. Hohui Eileen Wang of the University of California, San Francisco.

The study wasn’t designed to prove whether or how pre-deployment insomnia might directly cause PTSD or suicidal thoughts, and it’s possible insomnia might be both a risk factor and a symptom of PTSD.

“On one hand, PTSD can result in various sleep disturbances including nightmares, difficulty falling asleep, frequent awakenings and waking up too early,” Wang said by email. “On the other hand, insomnia adversely impacts physical ability and cognitive functioning and could put military personnel at higher risk of injuries and accidents which may result in PTSD.”

The connection between pre-deployment insomnia and PTSD and suicidal thoughts was explained in part by other things experienced during deployment like extreme stress, mental health problems and traumatic brain injuries, researchers found.

Once the study team accounted for other factors that might contribute to the risk, however, pre-deployment insomnia was still associated with a 50 percent higher risk of PTSD and a 43 percent greater risk of suicidal thoughts.

Among soldiers without any lifetime history of PTSD, pre-deployment insomnia was associated with a 55 percent higher risk of PTSD afterward, the study found.

And, among soldiers without any history of suicidal thoughts, pre-deployment insomnia was associated with a 67 percent greater risk of suicidal thoughts afterwards, the researchers report in the journal Sleep.

“These findings are consistent with a growing body of literature showing that insomnia is an important public health problem in active-duty military and highlight the importance of assessing and addressing insomnia in this population,” said Sanford Nidich, director of the Center for Social and Emotional Health at the Maharishi University of Management in Fairfield, Iowa.

“Effective treatments, easy to practice, transportable, and compatible with the military culture such as certain meditation and self-care programs, should be considered for military personnel who may face deployment,” Nidich, who wasn’t involved in the study, said by email.

In a separate study in Sleep, researchers examined data on more than 2,400 soldiers deployed to Afghanistan in 2011 and found sleep disturbances helped to partially explain the connection between combat exposure and PTSD, stress, aggression, alcohol use and risky behavior.

While it may not always be possible to consistently sleep well during deployments, helping soldiers sleep better afterwards may help ward off PTSD and problem behaviors, said the lead author of this study, Captain Jeffrey Osgood of the Center for Military Psychiatry and Neuroscience at the Walter Reed Army Institute of Research in Silver Spring, Maryland.

Good sleep practices that help civilians may help soldiers, Osgood said by email.

Most people are healthiest and perform their best with seven to nine hours of sleep, Osgood said. Soldiers getting less than six hours a night or struggling to fall or remain asleep should take steps to improve their bedtime routines, he advised.

“For many people, simply improving their sleep habits will help,” Osgood said. “Try to avoid caffeine, nicotine, and exercise in the hours leading up to sleep; avoid using alcohol as a sleep aid; don’t go to bed hungry; try to keep your bedroom dark and quiet; use sleep masks and/or earplugs if needed; and keep your smartphone/devices out of bed.”

SOURCE: bit.ly/2CnyVkE Sleep, online December 3, 2018; and bit.ly/2T4z1Dx Sleep, online December 17, 2018.