Sleep Disorders a 'Normal,' Stand-Alone Response to Combat?

No Link Between Sleep Disturbances and PTSD, TBI, or Other Psychiatric Disorders

Caroline Cassels

June 09, 2011

June 9, 2011 (Honolulu, Hawaii) — Sleep disturbances in returning veterans, including obstructive sleep apnea (OSA), may be a stand-alone, 'normal' response to combat exposure and not necessarily an indication of conditions such as posttraumatic stress disorder (PTSD) or traumatic brain injury (TBI), new research suggests.

Presented here at the American Psychiatric Association 2011 Annual Meeting by investigators at Walter Reed Army Medical Center (WRAMC) in Bethesda, Maryland, findings from a retrospective study buck the commonly held belief that sleep disorders in military personnel are almost always attributable to other conditions, most commonly PTSD or TBI.

"When we looked at this we found that indeed we weren't able to detect a connection between PTSD and OSA. We also looked at severity, thinking that perhaps patients with more severe PTSD had obstructive sleep apnea but that didn't bear out either," lead investigator Capt. Vincent F. Capaldi, ScM, MD, told Medscape Medical News.

The same held true for TBI, depression, non–PTSD-related anxiety, and participants with no psychiatric diagnosis, he said.

Sleep disorders are one of the leading concerns among military personnel returning from the wars in Iraq and Afghanistan. However, Dr. Capaldi noted that sleep-wake cycles in deployed soldiers are disrupted by necessity.

"In the combat field there are 24-hour operations that require people to stay up and work in shifts, so it is very difficult for them to get what they feel they need in terms of sleep," he said.

Sleep Deprived

According to a 2008 US Army Report, on average soldiers in Iraq get 5.6 hours of sleep, a significantly lower amount than the self-reported need for 6.4 hours to feel rested. In 2007, 16% of soldiers in Afghanistan were taking mental health–related medications, and of these 50% were for sleep problems.

Dr. Vincent Capaldi

Furthermore, said Dr. Capaldi, most soldiers from current conflicts in Iraq and Afghanistan report sleep disturbances 3 to 4 months after returning home. However, he noted, this is not surprising because recent research in Vietnam veterans shows sleep problems can endure for decades and that 100% and 90% of these veterans with and without, PTSD respectively, still endorse sleep problems.

Research in civilian populations has shown a strong self-reported/subjective link between sleep disturbances, OSA and trauma.

However, there has been no research objectively examining this potential association, and it remains unclear whether sleep disturbances are more prevalent among combat veterans with a specific diagnosis of PTSD, TBI, or other psychiatric diagnosis or whether they reflect a nonspecific symptom that is widespread among combat-exposed individuals.

More Nocturnal Awakenings

To address this issue, investigators conducted the retrospective study using the electronic medical records of 69 (60 men and 9 women) Operation Iraqi Freedom and Operation Enduring Freedom active duty soldiers who had recently returned from combat deployment and had been referred for polysomnography at WRAMC between 2006 and 2008. The cohort had a median age of 37.9 years.

When researchers examined OSA rates among soldiers with PTSD (75%) and without PTSD (77.5%), they found they found no significant difference between the 2 groups. Similarly, there was no significant difference in OSA severity in soldiers with PTSD and those without the disorder.

Similarly, the investigators found no significant differences in OSA rates in patients with or without TBI (83% vs 75%), depression (81.6% vs 71%), or other non–PTSD-related anxiety disorders (75% vs 77.4%).

However, further analyses revealed that participants with PTSD had more nocturnal awakenings than their non-PTSD counterparts, suggesting, said Dr. Capaldi, that they may have a lower threshold for waking up during the night.

The investigators also found that individuals with TBI had more slow-wave sleep than other subgroups. In addition, results revealed that younger patients were significantly more likely to receive antipsychotic medications than older patients.

These findings, said Dr. Capaldi, strongly suggest that organic causes of sleep symptoms, such as OSA, need to be investigated.

Exacerbation of PTSD Symptoms

Sleep apnea, he explained, can exacerbate PTSD symptoms because it heightens noradrenergic activity.

OSA, he explained, causes patients to have a "revved up noradrenergic response," which can make PTSD symptoms worse. On the flip side, he added, PTSD can also cause overactivation of the noradrenergic system, making patients who don't have OSA feel as though they do.

"So, for example, at night patients without OSA may feel as though they are being strangled, leading them to believe they have OSA when they actually don't," he said.

Dr. Capaldi noted that the long-term consequences of untreated OSA are "dire" and, in addition to contributing to serious cardiovascular risk, can complicate PTSD treatment.

"For example if your patient has this revved up neuroadrenergic system because of OSA, it is going to be much more difficult for you to treat the underlying PTSD than it would be in a person that doesn't have OSA."

Dr. Capaldi's next research steps include studying whether treatment for OSA, such as continuous positive air pressure, reduces PTSD symptoms and the impact of insomnia and nightmares as a cause of sleep disturbances.

Dr. Capaldi and his coinvestigators have disclosed no relevant financial relationships.

American Psychiatric Association (APA) 2011 Annual Meeting: Scientific and Clinical Reports, Session 14, No. 3. Presented May 15, 2011.

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