Most people come to yoga for a particular reason – it’s not just that they stumble into a class or have time to kill. Some come to it for the physical benefits – others are coming to yoga for the psychological benefits. Yoga has long been known for its magic on the mind: reducing anxiety, depression, monkey mind and helping us conjure up a greater sense of peace and a foothold in the present moment.
But this actually isn’t magic at all – it’s science. People have known and written about yoga’s mental effects for eons, but perhaps even more amazingly, we now have the tools to measure exactly what yoga and meditation can do for the body and brain. In fact, one of yoga’s most astounding benefits is that it’s been shown to have measurable effects on the body’s stress response system, which many of us could use a bit of help with.
The fight-or-flight response is a stress reaction that most people have heard of and experienced for themselves. The heart rate increases, blood pressure rises, breathing quickens, and the mind may start racing. What is particularly fascinating is that what was once reserved for running from a predator is now present in a chronic, low-grade kind of way for so many people. If the stress response is triggered in small ways all the time, it’s never really fully off. And this leads to all sorts of physical and psychological problems, from increasing cancer risk to increasing depression risk.
One effect that yoga has been shown to have on stress is to regulate the autonomic nervous system – the part that’s responsible for both the stress response and its counter, the relaxation response. One way it does this is by increasing the neurotransmitter GABA, which is known to be lower in people with anxiety disorders, depression, and post-traumatic stress disorder. In one study, people who were randomly assigned to take yoga classes vs. walking for 60 minutes a day, three times a week for 12 weeks, reported lower stress levels and improved mood. Which suggests that yoga, in contrast to other forms of activity, like walking, has the potential to influence our stress levels – not only in how we perceive stress, but also in objective measures of brain function.
Yoga has also been shown to help reduce levels of the hormone cortisol, the central stress hormone that’s released in the brain during times of stress. When cortisol is secreted over the long term, as it may be for people living with chronic stressors, it can affect our ability to learn and remember information. In one study, people with chronic illnesses had reduced cortisol levels (and greater endorphin levels) after just 10 days of doing yoga. They also had reduced levels of interleukin-6 (IL-6) and tumor necrosis factor, which are both markers of inflammation. Another study found reduced cortisol levels in college students after just one 90-minute session of hatha yoga. And some research has suggested that the brains of experienced practitioners may respond differently to negative stimuli than in non-practitioners.
The caveat is that though there have been many studies on stress and yoga, some have limitations – their samples sizes are too small, they’re not randomized, or there’s no control group. But even meta-analyses – large-scale studies that look at a number of smaller studies – have found that despite the limitations, many studies are well-executed enough to find a real effect, especially those looking at the physiology and biochemistry of how yoga affects the stress response.
Finally, it’s worth pointing out that meditation has also been shown to have strong effects on the stress response, including reduced activity in the famous “monkey mind” areas of the brain, which cause us to ruminate about the stressors in our lives. Meditation has even been linked to reduced grey matter volume in the brain’s amygdala, the area that governs fear and anxiety.
It’s pretty safe to say that yoga for stress reduction actually works, whether you’re doing asana or a sitting meditation. The practices may not be standalone treatments for everyone – if you’re severely stressed out and suffering from acute anxiety, you may need talk therapy or other treatments to fully treat it. But yoga is even being integrated into some of the “gold standard” methods, like cognitive behavior therapy. And mindfulness-based stress reduction (MBSR) has been shown in dozens of studies to be effective for stress and depression, as has mindfulness-based cognitive therapy (MBCT).
More research will be needed, but in the meantime, a regular practice of yoga or meditation seems to help. And just knowing that you have something to come back to may itself give you a sense of peace. People have known intuitively for many, many years that yoga can calm the mind – but it’s nice to have the scientific proof as well.
Alice G. Walton, PhD is a health and science writer, and began practicing (and falling in love with) yoga and meditation five years ago. She is a contributor at Forbes.com, and writes for the University of Chicago, as well as other publications. Of all the areas of health she covers, she’s particularly interested in how yoga and meditation affect the brain and behavior. You can follow her on Twitter @AliceWalton and Facebook at Facebook.com/alicegwalton.