Yoga is universally seen as the fast-track to emotional well-being and stability. It is also one of the prime examples when evidence-based research consistently sided with the popular perception of yoga. The amount of research on yoga and mental health grows as fast as the number of YouTube yoga videos.
So what evidence is there that yoga is good for mental health? What is the role of yoga in reducing stress, does yoga help with anxiety and how can yoga increase our mental and emotional capacity?
- Impulse control
Yoga practice is the antonym of stress. Anyone who has ever practiced yoga just once would agree that very few activities can have such a calming, harmonizing effect. The effectiveness of yoga for stress relief has been the subject of numerous studies. There are different ways to define what stress actually is and yoga consistently proves to be an effective way to combat stress regardless of its exact definition.
While there is still no clear understanding of how exactly yoga reduces stress, we can describe the general mechanism. It is generally accepted that stress reduction comes from a positive effect on either our Sympathetic Nervous System (SNS) or Parasympathetic Nervous System (PNS). In case you do not know, SNS is the system that prepares our bodies for “fight or flight” response during potential danger. Feels a bit stressful just to read about it, doesn’t it?
PNS is, on the opposite the part of our nervous system that helps restore our body to calm state and prevent overload. The research of yoga for stress management has been pointing to the positive effect of yoga practice on our vagus nerve.
It is the longest nerve of our whole autonomous nervous system that runs from our brain to the abdomen. It is a crucial element of our nervous system that affects processes from sweating to heart rate to muscle movements in our mouth. Research has consistently linked yoga practice to improved heart rate variability and blood pressure. Such changes are considered the direct evidence of the vagus nerve stimulation. Once we calm down the larges nerve in our autonomous nervous system, the positive effects propagate throughout the whole body. Our perception of a decrease in stress that we get from improvements in heart rate and blood pressure reduces the activation of the HPA axis, the second most important factor in the stress response.  HPA axis is the system composed of the Hypothalamus, Pituitary gland, and Adrenal Cortex. Altogether they regulate the production of cortisol. It is the famous stress hormone that keeps us alert, sometimes, when we would rather not be.
Yoga practice will improve our heart rate, modulate blood pressure, and decrease the amount of cortisol produced. While we do not yet know where this mechanism originates, we don’t have to stress over it and simply enjoy the sum of its positive effect. The evidence-based answer to the question does yoga help with stress is yes.
Another way yoga can help with mental health is by relieving anxiety. A recent experiment explored if yoga is good for anxiety, by observing the group of yoga-practicing healthcare workers.
Healthcare workers have one of the highest chances to suffer from anxiety and are generally at-risk when it comes to mental health. The observed group has taken a number of tests measuring their emotional wellbeing before and after participating in this yoga and anxiety experiment. The results showed that their Mental Composite Score-12 (part of the SF-12 tests commonly used to assess chronic conditions) have improved from 43.5 before yoga course to 48.1 after yoga course.
So what does the improvement of 4.6 of Mental Composite Score-12 actually mean? According to another research, aimed to investigate the accuracy of this test showed that the score of 45.6 is the cut-off for depressive disorders  So the improvement from 43.5 to 48.1 experienced by the healthcare workers thanks to yoga might as well mean the difference between depression and no depressions for some of them!
Yoga may as well be the synonym of impulse control, unless it is, of course, the impulse to unroll the mat in the morning. In some places, however, being impulse may be both common and dangerous. Yoga practice can help reduce impulsiveness even in an extreme environment. A 10-week yoga course demonstrated improvement in behavioral control, an increase in impulse control, and even a reduction in overall psychological distress among the prison population.
While it may be difficult to memorize a long yoga sequence right away, practicing it may actually help with that. Not just through “spaced repetition”  but also yoga practice actually improves our memory function. Multiple  studies  were conducted where people performed memory-intensive tasks right after yoga practice. The results showed that the group that practices yoga had more improvements in working memory than the group that performed aerobic exercise and the control group.
The long-term effects of yoga on memory have not been proven, however. So if you want to get some yoga boost for your memory, aim to do the memory-intensive task right after practice.
Yoga shows effectiveness even when tasked with improving the most serious psychological conditions. Research has consistently shown that yoga can help people with PTSD even regardless of the cause. Yoga was able to significantly reduce the symptoms of PTSD caused by both natural disasters  and after exposure to the dangers of combat or acts of terror. What is fascinating is that the studies explored both the short-term and long-term yoga courses in the context of PTSD treatment. In all cases yoga was effective, demonstrating both quick its acting effect and its staying power.