· manage stress/emotional regulation,
· manage anxiety
· lower blood pressure
· lower the heart rate
· Boost the immune system
· When used in conjunction with meditation to increase brain matter.
Andrew Weill, M.D. recognizes breathing techniques as a way to optimal health. And there are professional associations which focus on breath-work. This might be because of the pervasive benefits of optimal breathing:
The web site breathing.com offers a list of clinical studies into the health benefits of optimal breathing. One such study, which spanned a 30-year period, concluded that the most significant factor in your health and longevity is how well you breathe. It focused on the long-term predictive power of forced exhalation volume as the primary marker for life span.
Studies have found, for example, that breathing practices can help reduce symptoms associated with anxiety, insomnia, post-traumatic stress disorder, depression and attention deficit disorder.
“Breathing is massively practical,” says Belisa Vranich, a psychologist and author of the book “Breathe,” to be published in December. “It’s meditation for people who can’t meditate.”
Controlled breathing will slow the heart rate, promote feelings of calm, which in turn will reduce stress and the body’s production of stress hormone. Optimal breathing will reduce overall inflammation which in turn will turn back the clock on aging.
There are various breathing methods such as using counts for the inhale, hold, exhale and hold. Dr. Weill advocates for 4-7-8 breathing to relax and Bellows Breath to increase energy and alertness. There are many other recognized techniques.. There is even a book which will walk you through breathing exercises for breathing efficiency and then separate methods for controlling emotional response: Breathe by Dr. Belisa Vranich.
Many people may recognize breath-work through yoga . In the Yogic tradition breath is equivalent to life-force or pranayama:
Prāṇāyāma (Sanskrit: प्राणायाम prāṇāyāma) is a Sanskrit word alternatively translated as "extension of the prāṇa (breath or life force)" or "breath control." The word is composed from two Sanskrit words: prana meaning life force (noted particularly as the breath), and either yama (to restrain or control the prana, implying a set of breathing techniques where the breath is intentionally altered in order to produce specific results) or the negative form ayāma, meaning to extend or draw out (as in extension of the life force). It is a yogic discipline with origins in ancient India.
Interestingly, this Eastern Philosophy of Yogic breathing seems to mirror Torah. Hebrew recognizes breath as being spiritual and linked to vitality. The words “soul” and “breath” are the same: nun sheen mem. Neshuma – soul – nishuma - breath. And the words breath and spirit are the same: “ruach” being wind, breath liveliness and vigor.  The Torah makes precise reference to nose breathing as being the proper manner :"God formed man out of the dust of the ground, and breathed into his nostrils a soul-breath of life (Nishmat Chaim)." (Genesis 2:7). And remembering that soul and breath are the same: Psalm 150 provides that all souls will praise Hashem. So, the Malbim brings down that all souls will praise Hashem for every breath we take.
So, there is a recognized importance to controlling and recognizing breathing for spiritual, physical and emotional well-being. Proper breathing and controlled breathing, separate practices, are essential for vitality and peace of mind.
 Blackburn [Nobel Prize for her work in Genetics] and Eppel, The Telomere Effect A Revolutionary Approach to Living Younger Healthier Longer (2017) and Breathe by Dr. Belisa Vranich (2017)
 Benson, The Relaxation Response, Harper Torch 1979; http://www.health.harvard.edu/mind-and-mood/relaxation-techniques-breath-control-helps-quell-errant-stress-response
 http://breathworkalliance.com/; http://www.ibfnetwork.com/about_the_ibf
 See footnote one.
 http://healthland.time.com/2012/10/08/6-breathing-exercises-to-relax-in-10-minutes-or-less/; https://www.nytimes.com/2016/11/09/well/mind/breathe-exhale-repeat-the-benefits-of-controlled-breathing.html?_r=0; http://psychcentral.com/blog/archives/2013/07/22/reduce-your-anxiety-this-minute-3-different-types-of-deep-breathing/; http://www.normalbreathing.com/learn-8-diaphragmatic-breathing.php
 Kollel of Cherry Hill, New Jersey