A new study from Boston University School of Medicine finds that yoga significantly increases levels of the neurochemical GABA, which is related to mood, anxiety, and sleep. Completing one yoga class per week may maintain elevated GABA levels, which ease depressive symptoms. Study results showed that GABA levels after three months of yoga were elevated compared to pre-yoga levels for about four days after the last session. The increase was no longer observed after about eight days. Depression affects approximately 16 million people in the U.S. every year and is the leading cause of disability worldwide.