Women enrolled in a small study reported a reduction in symptoms of posttraumatic stress disorder (PTSD) after a series of yoga classes.
However, women in a comparison group that didn't take the classes also reported a similar decline in symptoms, researchers found.
"The yoga group did well - they improved in their PTSD symptoms - and our control group actually did well, which we didn't expect," Karen Mitchell told Reuters Health.
Mitchell, from the National Center for PTSD at the VA Boston Healthcare System, led the new study.
"I do emphasize that the yoga (group) definitely didn't do worse," she said. "Yoga could potentially be triggering for people with trauma, so while that's not as exciting a finding, I think it is important to say that."
About one in 10 U.S. women is affected by PTSD, according to the authors. Many say that alternative and complementary therapies - such as yoga - help them cope with the symptoms, which can include trouble sleeping and having flashbacks related to the traumatic event, known as re-experiencing.
"It can be very debilitating and in the general population it affects women about twice as often as men," Mitchell said. Her team's findings were published in the Journal of Traumatic Stress.
A total of 26 women with PTSD completed the study. The women were an average of 44 years old and included both civilians and military veterans.
Fourteen of the women attended weekly yoga sessions for 12 weeks or twice-weekly sessions for six weeks. Each session was 75 minutes long and focused on mind-body connections, breathing and physical postures. Women also filled out a symptom questionnaire each week.
Twelve women in the comparison group met once per week for 12 weeks in small groups to complete the same questionnaires.
All participants completed a follow-up assessment one month after the sessions ended.
Mitchell and her colleagues found that women in both groups had significant improvements in their symptoms. The yoga participants showed decreases in re-experiencing and hyperarousal symptoms, while the comparison group reported improvements in re-experiencing symptoms and anxiety.
"Both groups were doing assessments, coming in every week, and interacting with us - doing these kinds of things that might have been helpful for both groups," Mitchell said.
Studies that include more women will be needed in the future, she added.
"There are several proposed mechanisms on how yoga may help reduce PTSD symptoms," Julie Staples told Reuters Health in an email.
Staples led a previous study on the same topic at the Southeast Louisiana Veterans Health Care System in New Orleans. She was not part of the new research.
"Simply stated, yoga may regulate aspects of the endocrine system and the nervous system that are out of balance in PTSD," Staples said. "Yoga also reduces the stress response which plays a role in PTSD symptoms."
Two of her colleagues, Michelle Hamilton and Madeline Uddo, said veterans' responses to the Louisiana yoga program have been very enthusiastic and they report an immediate benefit - feeling better when they leave the class as well as noticing a positive impact on their daily life.
Mitchell said people who are interested in trying yoga but don't know much about it should shop around to find a style they like.
"It varies so much in terms of style and pace - some people might do better with a slower style that gives them space to meditate and think," she said. "Some people need the faster pace to help them focus - their minds might wander too much and they start thinking about their to-do list with a slower pace class."
Yoga instructors vary in their personality and style and that's important too, Mitchell added.
"You want to feel comfortable with your instructor, especially if you're new to this - you want to know that they'll come around and help you align and feel comfortable with them doing that so you don't hurt yourself and also you have a more positive experience if you feel connected with the instructor," she said.