Yoga can improve the mood and mental wellbeing of prisoners, and may also have an effect on impulsive behavior, an Oxford University study published on Thursday suggests.

Reported their findings in the Journal of Psychiatric Research, researchers said prisons see rates of mental health problems that are many times higher than the general population.

Inmates from a range of ages were randomly assigned to either a course of ten weekly yoga sessions of 90 minutes, or to a control group.

"We found that the group that did the yoga course showed an improvement in positive mood, a decrease in stress and greater accuracy in a computer test of impulsivity and attention," said Dr Amy Bilderbeck, who led the study.

If yoga is associated with improving behavior control, as suggested by the results of the computer test, there may be implications for managing aggression, antisocial or problem behavior in prisons and on return to society, researchers noted.