New York ? Touch toes. Downward dog. Breathe. It’s a yoga routine that cancer doctors have prescribed for years without evidence it would do much good.

Now the biggest ever scientific study of yoga finds their instincts were right.

While yoga doesn’t cure the disease, its stretching and breathing exercises did improve sleep, reduce dependence on sedatives and help cancer patients resume the routine activities of everyday life, according to a 410-participant study being highlighted at the American Society of Clinical Oncology’s annual meeting in Chicago next month.

Health insurers and government programs don’t pay for yoga even as mounting evidence from dozens of smaller studies show benefits for treating chronic disease. The research and more than $5 million in additional tests funded this year by the National Institutes of Health may convince skeptical doctors and provide scientific evidence to allow coverage.

“Clinicians should now feel pretty comfortable prescribing gentle Hatha yoga or restorative yoga for their patients,” said Karen Mustian, lead author of the study and assistant professor in the department of radiation oncology and preventive medicine at the University of Rochester Medical Center. “The data from this study is one of the first steps in the direction toward insurance coverage, but we’re not there yet.”

Doctors at Beth Israel Medical Center in New York aren’t waiting for more studies to start prescribing yoga. The hospital is one of the few facilities in the country to offer personal yoga therapy instruction for all of its sickest cancer patients.

Yoga began in India as a combination of physical and mental exercises. Historians have traced its roots back thousands of years to references in Buddhist and Hindu texts. In Western practices, muscle-stretching poses are accompanied by meditative breathing exercises.

About 15.8 million Americans practiced yoga in 2008, according to a study commissioned by Yoga Journal.