The adrenal glands secrete the stress hormone cortisol in response to an acute crisis. When people are regularly stressed, their cortisol levels may be chronically elevated. Persistently elevated levels of cortisol can have adverse effects on the immune system, on body weight, and on memory. (source: Timothy McCall, M.D.)
Category Archives: Yoga Gem
A study at Benares Hindu University found that three- and six-month practices of yoga lessened depression. The practice consisted of relaxation poses, inversions, and other asana, pranayama, and mediation. The yoga group and a comparison group treated with an antidepressant showed similar improvements in neurotransmitter levels, both experiencing a significant rise in serotonin levels and a decrease in the levels of cortisol and monoamine oxidase. Such changes may help to improve mood. (source: Timothy McCall, M.D.)
Adapted from “The Heart of Yoga”
How does our perception work? We often determine that we have seen a situation “correctly” and act according to that perception. In reality, however, we have deceived ourselves, and our actions may bring misfortune to ourselves or others. Just as difficult is the situation in which we doubt our understanding of a situation when it is actually correct, and for that reason we take no action, even though doing so would be beneficial. In yoga terminology, this is called Avidya – literally meaning “incorrect comprehension.” The opposite is Vidya, “correct understanding.”
Our incorrect comprehensions are very rooted in us because we often live life through a series of many unconscious actions and ways of perceiving that we have been carrying out for years. As a result of these unconscious responses, the mind has become more and more dependent on habits until we accept the actions of yesterday as the norms of today. Such habituation in our action and perception is called Sam Skara. These habits cover the mind with Avidya, as if obscuring the clarity of consciousness with a filmy layer.
If we are sure we do not clearly understand a given situation, generally speaking we do not act decisively. But if we are clear in our understanding we will act and it will go well for us. Such an action stems from a deep level of perception. In contrast, Avidya is distinguished by superficial perception. I think I see something correctly, so I take a particular action and then later have to admit that I was mistaken and that my actions have not proved beneficial. So we have two levels of perception: One is deep within us and free of this film of Avidya, the other is superficial and obscured by Avidya. Just as our eye is transparent and clear and should not itself be tinted if it is to see colors accurately, so should our perception be like a crystal-clear mirror. One goal of yoga is to reduce this film of Avidya in order to perceive and act correctly.
If you are still enough, the wild mind, the mind that isn’t preoccupied with oughts and shoulds and the minutiae of life, will approach you and make itself known.
Yoga has been shown to improve coordination, reaction time, memory, and other measures of effective brain function. When you study yoga, you are learning completely new ways to move the body, and coordinating different actions simultaneously. Beyond all the variety in asana, there are breathing techniques, visualizations, mantras, and different kinds of meditation. Each of these activities causes the brain to build new synapses, the connections between neurons. Scientists now believe that continuing to learn new things into older age is one key to increasing neuroplasticity and maintaining brain function. Yoga also teaches you to focus your attention. (source: Timothy McCall, M.D.)
To say that yoga simply relaxes the nervous system is an oversimplification. Many yogic practices, like backbends and strong pranayama techniques, actively stimulate the SNS, so yoga’s benefits can’t be reduced to just relaxation. What you want is an ANS that’s finely tuned to respond to whatever stresses life brings, shifting the relative activation of the PNS and SNS as needed. My guess is that yoga, by a combination of stimulating and relaxing practices, tones the nervous system to give it this flexibility. Researchers analyze the function of the ANS by looking at such factors as how well the body senses and adjusts to changes in body position (baroreceptor sensitivity) and whether the heart maintains a healthy though subtle variation in its rhythm (heart rate variability). Yoga appears to improve both of these measures. (source: Timothy McCall, M.D.)
When people talk about stress reduction, they often mean changing the balance between the two branches of the autonomic nervous system (ANS), switching it from a hyper-vigilant state, mediated by the sympathetic nervous system (SNS), to relaxation, mediated by the parasympathetic nervous system (PNS). The ANS regulates the function of internal organs such as the heart, lungs, and intestines; it is sometimes dominated by the SNS and sometimes by the PNS, depending on the circumstances. The SNS, the “fight or flight” response, becomes more dominant in emergencies. When there is now perceived emergency, the PNS dominates. The PNS is calming and restorative; it lowers the breathing and heart rates, decreases blood pressure, and increases blood flow to internal organs such as the intestines and reproductive organs, allowing you to “rest and digest.” These effects, which are the opposite of fight-or-flight, constitute what Dr. Herbert Benson has dubbed “the relaxation response.” The system he popularized to elicit it, which involves closing the eyes, following the breath, and repeating a word or phrase, is directly modeled on Transcendental Meditation (TM), a type of yogic mantra meditation, though other yogic tools including asana and pranayama can similarly shift stress in a wide variety of medical problems – not just the obvious ones like migraines and insomnia. (source: Timothy McCall, M.D.)
Several studies have found that people who begin regular yoga programs lose weight. In addition to weight loss, one study found significant reductions in fat folds – at the back of the arms, beneath the shoulder blades, and in several other locations – as well as in body circumference. Beyond the calories burned by practicing yoga, there can also be a spiritual and emotional dimension that yoga addresses; this may be part of the reason that many people find that yoga works for them when prior attempts at weight loss have failed. Yoga also brings a higher level of consciousness to eating and fueling and nourishing one’s body, which can often contribute to weight loss. (source: Timothy McCall, M.D.)
Even yogic postures and sequences that don’t bring your heart rate into the aerobic range can improve your cardiovascular conditioning. Studies have found that yoga practice lowers the resting heart rate and increases the maximum uptake of oxygen as well as endurance during exercise, all indications of improved aerobic conditioning. In people with heart disease, a comprehensive lifestyle program that included yoga asana resulted in an improvement in the heart’s pumping ability. One study found that subjects who practiced just pranayama (breathwork) could work harder with reduced oxygen consumption. (source: Timothy McCall, M.D.)
An unpublished study done at California State University, LA, found that six months of yoga, focusing on standing poses, significantly increased bone density in the vertebrae in 18 women between the ages of 18-65, compared to the control group, who maintained their usual physical activity. In addition, yoga’s documented ability to lower levels of the stress hormone cortisol may help keep calcium in the bones because excess cortisol both decreases bone formation and increases its breakdown. (source: Timothy McCall, M.D.)