Hatha yoga is a branch of yoga that emphasizes physical techniques, including postures (asanas), breathing exercises (pranayama) and mudras or hand gestures, to balance the body and mind. The term "Hatha" combines the Sanskrit words for "sun" (ha) and "moon" (tha), symbolizing the balance of opposites within the body.

Hatha yoga breathing techniques can be traced back to the 1st Century in both Buddhist and Hindu texts. The resonant sound of OM which becomes an internal sound one perceives at this stage of the training, and also other sounds which arise in deep meditation.

The National Institutes of Health's National Center for Complementary and Integrative Health analyzed dozens of peer-reviewed studies, and while most of the research was performed on small numbers of subjects, they found evidence to suggest yoga may be beneficial for the following conditions

• Anxiety and depression: Yoga can help relieve everyday anxiety and depressive symptoms, however, it may not be effective for clinically diagnosed mental health conditions. The NCCIH reviewed 68 published studies on yoga and did not find conclusive evidence to support its effectiveness for managing anxiety disorder, depression, or PTSD.

• Arthritis and fibromyalgia: According to the NCCIH, there is little evidence to support yoga has benefits for osteoarthritis, rheumatoid arthritis, and fibromyalgia.

• Back pain: The American College of Physicians recommends yoga as a non-drug method to treat back pain. A review of eight studies by the Agency for Healthcare Research and Quality found yoga improves lower-back pain and function with both short- and intermediate-term benefits, and its effects are similar to other types of exercise.

• Balance: Yoga helps to improve balance in healthy people, according to 11 out of 15 studies reviewed by NIH.

• Emotional health: Yoga has a positive impact on mental health and was shown to have benefits of improving resilience or general mental well-being in 10 out of 14 studies reviewed by NCCIH.

• Menopause: Yoga can relieve physical and psychological symptoms of menopause, including hot flashes, according to the NCCIH review of more than 1,300 study participants.

• Mindfulness: In a survey of 1,820 young adults published in the International Journal of Behavioral Nutrition and Physical Activity, participants attributed greater mindfulness, motivation to participate in other forms of activity and eat healthier, and the influence of a health-minded yoga community to practicing yoga regularly.

• Multiple sclerosis: Yoga has been shown to have short-term benefits on mood and fatigue in people with multiple sclerosis, however, it was not found to affect muscle function, cognitive function, or quality of life, the NCCIH reports.

• Neck pain: A meta-analysis published in the journal Medicine including 10 studies and a total of 686 subjects found that yoga can reduce neck pain intensity and disability from pain while also improving the range of motion in the neck.

• Sleep: Several studies reviewed by NCCIH have found yoga can improve sleep quality and duration. Populations found to experience sleep benefits from yoga include cancer patients, older adults, people with arthritis, pregnant women, and women with menopause symptoms.

• Stress management: Yoga was shown to improve physical or psychological measures related to stress in 12 out of 17 studies reviewed, according to NCCIH.