Here's a quick clip of Dr Chris Streeter from the Department of Psychiatry and Neurology, Boston University School of Medicine.
Here she talks about a study in which she and her team observed that in comparison to one hour of walking, one hour of yoga increased activity in the brains GABA system. GABA (gamma amino-butryic acid to give it its official title) is a neurotransmitter, a substance critical for nervous system functioning. Medications used to treat depression and anxiety work in part by increasing activity in the GABA system. Streeter also observed that as GABA levels went up, participants reported improved mood. This ground breaking research provides a good basis with which to suggest that yoga can be helpful in the management of stress, anxiety and depression amongst other common disorders that are linked with altered GABA activity.