The primary pathway of the PNS is through the 2 vagal nerves, each of which contains multiple pathways.9 Approximately 30% of vagal fibers are efferent and carry messages that descend from the brain to the body. The remaining 70% of vagal fibers are afferent, carrying sensory information from within the body up to the brain. These ascending messages have a strong impact on stress response, emotions, social engagement, neurohormones, and other critical functions.9 The Polyvagal Theory suggests that the vagal nerves are “major conduits for bidirectional communication between the brain and the body.”10,11 Additionally, underactivity of the inhibitory neurotransmitter gamma amino-butyric acid (GABA) is associated with depression, anxiety, PTSD, and other psychiatric disorders.12

Yoga exerts a profound impact on the PNS. In classical yoga, physical postures are accompanied by breathing techniques, but breathing techniques are also used independently. Specific slow forms of yoga breathing have been found to correct the underactivity of the PNS and GABA systems, theoretically through stimulation of the vagal nerves.12

Yoga Breathing in Psychiatry

Breathing practices “entail voluntary changes in the rate, pattern, and quality of respiration.”12 Numerous types of yoga breathing exist, and each practice has multiple variations that result in different psychophysiological effects.12

The techniques include:

·       Paced breathing: controlling the respiratory rate and relative length of 4 phases of the breath cycle

·       Coherent/resonant breathing: the length of inhalation and exhalation are equal, with only a slight pause between

·       Resistance breathing: partially obstructing airflow using laryngeal contracture, vocal cords, pursed lips, or other means, which produces sounds or vibrations

·       Unilateral or alternate nostril breathing: closing one nostril so that all air flows through the other

·       Moving the breath: engaging the imagination to move one’s breath through different parts of the body

·       Breathing with movement: coordinating paced breathing with physical movements

“Many mind-body practices help to correct imbalances in the ANS and lead to calmness, but we have found that the most useful, efficient, and simple way is through breathing techniques because they quiet the overactivity of the SNS and also increase the action of the PNS,” Dr Gerbarg said.

In particular, coherent breathing (also called resonant breathing) is easy to incorporate into psychiatric practice, Dr Gerbarg pointed out. This gentle technique involves breathing in and out through the nose with equal length of inspiration and expiration and between 4.5 and 6 breaths per minute for most adults.11 Coherent breathing can help a patient with anxiety to reduce or even discontinue benzodiazepine treatment, she said.

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While mindfulness meditation has been shown to have a major role in psychiatric practice as a stand-alone intervention or as a component of other interventions such as dialectical behavior therapy,13 some anxious people may find it difficult to start with meditation, Dr Gerbarg noted. She suggested that psychiatrists begin teaching patients coherent breathing before recommending mindfulness practices, especially for patients who might have difficulties with cognition, mental focus, coordination, the effects of sedating medications, or psychosis.

Other breathing practices, such a rapid intense breathing, can be stimulating and might be helpful for patients with depression; however, these techniques can have an adverse effect in patients with uncontrolled bipolar disorder, agitation, or psychosis. “It is important to learn which practices are most useful in particular clinical situations,” she said.

Together with Richard Brown, MD, Dr Gerbarg has developed a breathing practice called Breath-Body-Mind, which integrates coherent breathing with movement, visualization, and relaxation. The approach has been adapted and used in workshops for large groups of survivors of trauma, such as war or natural disasters, both in the United States and worldwide. “Breathing and movement classes are universally acceptable and beneficial, even in highly traumatized people, including adults and children in different cultures,” she reported. The practices are also useful with patients as adjunctive treatment in psychotherapy. “They provide acute, rapid reduction in anxiety, and if the patient practices regularly, building up to 20 minutes once or twice daily, long-term benefits accrue,” she said. These include increased resilience, less overreactivity, improved cognitive function, increased ability to experience positive emotions, and improved capacity for relating to others.

Some evidence also links breathing practices with reductions in cravings in those who suffer from addictions.14,15