Experts not directly involved with the research called the study important.
"This trial will provide a solid contribution to the literature and provides good evidence that yoga may be an effective therapy to improve symptom control following a cancer diagnosis," said Lee W. Jones, an exercise physiologist at Duke University in Durham, N.C.
"This is groundbreaking," said Kathryn Schmitz of the University of Pennsylvania School of Medicine and author of soon-to-be-released guidelines on exercise in cancer survivors. Particularly exciting, Schmitz said, is the fact that this type of intervention can be applied in community settings based on oncologists' recommendations, rather than just in hospitals or academic centers.
"Cancer patients trust their oncologists," she said. "If they're going to be physically active, they need to know what they're going to do is okay with their oncologists, even after treatment."
Complementary and alternative medicine (CAM) is widely sought by cancer patients and survivors, with a recent study estimating its use among 31 to 84 percent of pediatric cancer patients. In 2008, the National Cancer Institute supported approximately $121 million in CAM-related research.
Dr. Michael Irwin, professor of psychiatry and biobehavioral sciences at the UCLA David Geffen School of Medicine, is researching the use of tai chi in survivors. Like yoga, tai chi is a system with roots in Asia that incorporates stretching, gentle movements and the mind-body connection.
Irwin thinks tai chi and yoga may work by similar mechanisms.
"Yoga as well as tai chi both incorporate exercise," he said, "and some of the benefits may be through getting people up and moving around."
It's not entirely clear from a biological perspective why the yoga participants in this study saw improvements in their sleep problems and fatigue.
"If you break down the program into its basics -- breathing exercises, postures, mindfulness -- it's not entirely clear which component ... is most important," Mustian said. "It could be they all work together to improve sleep, fatigue and quality of life ... or it could be that one of them is really the most important piece."
Mustian recommended that cancer survivors interested in starting a yoga program to deal with sleep problems seek out gentle hatha yoga and restorative yoga classes. She also recommended seeking out instructors who have experience working with cancer survivors or other patients with chronic illnesses.
"There are some potential modifications they may want to make for survivors with certain physical limitations," she said.
Distler said she would "absolutely" recommend the practice for cancer survivors with sleep problems.
"It's a tool we can take with us and use," she said. "It's great because you can do it anytime, and it has lots of positive benefits and no negative side effects."