Prisoners who practice transcendental meditation twice a day may experience less stress and fewer mental health issues than fellow inmates who don’t meditate, a small U.S. study suggests. Previous research has linked this type of meditation involving mantras and mindfulness to reduced stress in a variety of populations at risk for mental health problems, including trauma victims, refugees and military veterans. For the current study, researchers offered 90 male inmates in Oregon state prisons a five-session training program in meditation then asked them to practice the techniques they learned twice daily for 20 minutes. Researchers also followed a control group of 91 inmates who didn’t receive any intervention. After four months, all the men showed some improvement in symptoms, but men in the meditation group reported significantly larger reductions in perceived stress, anxiety, depression, dissociation and sleep disturbances than the inmates who didn’t participate in this program, the study found. For depression and sleep problems, symptom scores were reduced by half, on average, among men who meditated, as was their total trauma score. Researchers evaluated the transcendental meditation program at the Oregon State Correctional Institution, a medium-security prison, and the Oregon State Penitentiary, a maximum-security facility.