A new study of young US veterans shows that the probability of having a high risk of obstructive sleep apnea (OSA) increased with increasing severity of post-traumatic stress disorder (PTSD) symptoms.

The study involved 195 Iraq and Afghanistan veterans who visited a VA outpatient PTSD clinic for evaluation. Results show that 69.2% of participants had a high risk for sleep apnea, and this risk increased with PTSD symptom severity. Every clinically significant increase in PTSD symptom severity was associated with a 40% increase in the probability of screening as high risk for sleep apnea.

“The implication is that veterans who come to PTSD treatment, even younger veterans, should be screened for obstructive sleep apnea so that they have the opportunity to be diagnosed and treated,” says co-principal investigator Sonya Norman, PhD, researcher at the San Diego VA, director of the PTSD Consultation Program at the National Center for PTSD, and an associate professor of psychiatry at the University of California San Diego School of Medicine, in a release. “This is critical information because sleep apnea is a risk factor for a long list of health problems such as hypertension, cardiovascular disease and diabetes, and psychological problems including depression, worsening PTSD and anxiety.”

The study idea was initiated by Tonya Masino, MD, who recognized that a surprising number of younger veterans who were coming to the clinic for PTSD treatment also were presenting with OSA symptoms. Study results are published in the May 15 issue of the Journal of Clinical Sleep Medicine.

Ninety-three percent of study participants were men, and their mean age was 33 years. Sleep apnea risk was evaluated using the Berlin Questionnaire, and PTSD was assessed using the PTSD Checklist Stressor Specific Version (PCL-S) questionnaire. Analyses controlled for potential confounders such as older age, smoking status, and use of central nervous system depressants.

According to the authors, younger veterans with PTSD are rarely screened for sleep apnea and frequently remain undiagnosed. They noted that the mechanism underlying the relationship between OSA and PTSD in military veterans is unclear. However, potential factors that may connect the two disorders include disturbed sleep in combat, prolonged sleep deprivation, sleep fragmentation and hyperarousal due to the physical and psychological stressors of combat, the chronic stress from PTSD, or the sleep disturbances caused by OSA. Longitudinal studies are needed to examine the temporal relationship between sleep apnea and PTSD.

The study was led by Norman and co-principal investigator Abigail Angkaw, PhD. The lead author of the study is Peter Colvonen, PhD.

According to the National Center for PTSD of the U.S. Department of Veterans Affairs, PTSD symptoms such as nightmares or flashbacks usually start soon after a traumatic event, but they may not appear until months or years later. Symptoms that last longer than 4 weeks, cause great distress or interfere with daily life may be a sign of PTSD. To get help for PTSD, veterans can call the Veterans Crisis Line at 1-800-273-8255 and press 1, text 838255, contact a local VA Medical Center, or use the online PTSD program locator on the VA website.