Perhaps more than ever, yoga has been widely studied and evaluated for its positive effects and benefits. Evidence-based research not only reveals the science of yoga but also explains its therapeutic efficacy when used in conjunction with conventional medicine. Studies show that regular long-term yoga practice improves immune function, reduces perceived stress, enhances mood, controls the effects of asthma, slows the aging process, regulates respiration (affecting emotional states), and creates a sense of well-being.

There are many components to yoga practice and this varies depending culture and commitment to practice. The studies measured the effects of postures, breathing, relaxation and meditation on people who practiced yoga regularly. Yoga postures improve strength, respiration and flexibility. Breathing techniques help with self-regulation which increases resilience and creates equanimity. Relaxation generates awareness, mindfulness and concentration. Meditation is a spiritual practice leading to transcendence, other states of being and ultimately to a unitive state of oneness. 

What is yoga’s effect on stress?  Stress underlies all things and alters every aspect of life. It is defined as a positive or negative challenge, either short or long term. Not all stress is bad, as we need it in certain challenging situations. In the immediate moment, it can save your life. It is in place for us as a protection. No stress can lead to boredom or apathy. Life circumstances, personality, genetics and health & lifestyle affect our stress response. How well can you recover from stress? How much stress can you tolerate? What is your sense of control? What is your perceived stress and can you adapt positively? Stress is in the eye of the beholder and changes over time. Creating balanced stress is the key to happiness. Resilience is important. Unmanaged chronic stress is cumulative and can be harmful to your mood and your immune system (causing inflammation). One’s attitude and life circumstances affect stress response. Using yoga as a modality for dealing with stress, students of yoga learned to manage and reduce stress levels. In some studies, the primary reason for beginning a yoga practice was to build muscle and create flexibility. However, over time, students noticed that yoga improved their mental health. Then stress relief became the motivation for continued practice. Their ability to regulate emotions, stay calm and centered proved that yoga was a valuable strategy in manipulating stress. People were less reactive and able to bounce back more quickly in response to high stress moments. Stress was measured by cortisol and other hormones and blood pressure as well as perceived stress. Yoga reduces maladaptive behaviors and triggers the relaxation response and quiets stress. Deep breathing exercises (Pranayama) regulate the autonomic nervous system by deactivating the sympathetic nervous system and activating the parasympathetic nervous system.

 Studies show that yoga affects our pulmonary function. Practicing Pranayama can be therapeutic making respiration more efficient, enhancing heart rate and reducing blood pressure. This regulation of vital body function creates a calm psychological state of being. Changing breathing patterns, making them longer and deeper, control the nervous system and brain states inducing a steadiness of mind. This diaphragmatic manipulation of the breath results in less reactivity and more equanimity. Respiration affects emotions and vice versa. It is your first line of defense in the treatment of anxiety and depression as well as other emotional disorders. Modulating the breath affect your psychological state. Stress regulation works with your limbic system, your emotional brain. Tension, anger, and depression drop with slow regular breathing techniques. Long, slow deep breathing makes the lungs more efficient as more air expands into the lungs, and changes your emotional state. In addition, rapid and shallow Kapalabhati breathing is beneficial as well in cleansing the body. Some yoga practices also include breath retention, Kumbhaka, stretching lung capacity.

Research has shown the positive effects of yoga in the treatment of chronic diseases of the lungs. It can control symptoms as well as avoiding triggers. Stress, allergies, infection, cold and exercise can induce an episode of asthma. But with a regular yoga practice, the inflammatory response can be reduced. There is a psychological aspect of this, too. Stress, anxiety, and sadness suggest the psychophysiological effect of the disease. The brain plays a critical role in this process. The stress hormone cortisol affects the inflammatory response. Mind-body practices help address the underlying causes of asthma. Self-regulatory components of yoga have an effect. Fitness, self-awareness, focused attention and spirituality affect respiration.  Studies shows immediate positive effects of yoga as well as long term effects. Practicing yoga regularly controls the rate of breathing and anxiety associated with asthma. Diaphragmatic breathing used as an intervention improves the negative effects of triggers.

Depression and yoga research concludes that practicing yoga has a major effect on the mood. Loss of interest in daily activities, sleep disturbance, fatigue, sense of worthlessness, and lack of concentration are a few indicators of depression. Mind-body practices have been shown to regulate the autonomic nervous system. In the case of depressive moods, we can up-regulate to bring about a feeling of alertness and focused. With the practice of yoga we can change brain function. When body systems are dysregulated, yoga proves to be a good treatment in reducing dysfunction. With self-regulation we can control internally. This inner awareness includes observing and regulating negative thoughts which enhances mood and helps cope with emotions. The physical practice, the relaxation and meditative parts of yoga training reduce the stressors that cause depression and thus creating emotional balance.

Yoga has a significant effect on the immunes system. Your immune system is a complex defense system involving organs, tissues and molecules in the blood stream. It feeds back to the brain as the brain feeds back to the immune system. Chronic stress equals chronic disease. Prolonged consistent stress degrades the system causing inflammation. This makes you more prone to illness.  Psychoneuroimmunology shows how the brain interacts with the immune system. Some short term or acute stress can be good for you and improves your immune response. However, overactive stress has the reverse impact. Healthy ways to improve immunity are diet, exercise, weight control, minimize stress and adequate sleep. Another cause of impaired immunity is sleep deprivation or disturbance which can leave you vulnerable to disease as well as reduce antibody production and cell function. Mind-body practices create resilience balancing immune function. Yoga stretching, controlled breathing, self-awareness down regulate the body. Mindfulness and meditation have relevance to immune function by changing behavior, thus reducing the propensity of disease. Programs like Mindfulness Based Stress Reduction increase the antibody response and prevent disease.  Our ability to handle stress can boost immunity. Studies demonstrate how cancer patients doing a regular yoga practice can improve the number of natural killer cells in the body. The research shows a significant reduction in cortisol and adrenaline which enhance the immune system. Over time results show improvement in stress and immunity. Efficient stress modulation reduces susceptibility of illness.

Yoga also slows down the aging process. As we age, we become more vulnerable to disease. Research shows that mild, gentle restorative yoga affects brain function, improves balance and flexibility. With mindfulness and meditative practices, the elderly can maintain cognitive faculties and performance.  It will improve the quality of life, sleep and overall well-being. The decline in the physical as well as the psychological aspects of life will be lessened.

The variety of health or well-being outcomes targeted by yoga intervention is impressive. Evidence shows that regular yoga practices improve quality of life.  Formal studies published by the medical and psychological community that used yoga interventions to promote or treat physical and mental health clearly document the benefits of yoga.