Guest post by Dr. Shawna Darou, ND
The autonomic nervous system regulates involuntary functions in the body including heart muscle, smooth muscles, the muscles of the intestinal tract and the glands. There are two parts to the autonomic nervous system, the sympathetic nervous system which constricts blood vessels, raises blood pressure and increases heart rate (‘fight or flight’); and the parasympathetic nervous system which slows the heart rate, increases intestinal activity and relaxes sphincter muscles (‘rest and digest’).
What is the vagus nerve?
The vagus nerve is the longest nerve in the body which originates in the brain as cranial nerve ten, travels down from the neck and then passes around the digestive system, liver, spleen, pancreas, heart and lungs. This nerve is a major player in the parasympathetic nervous system, the ‘rest and digest’ part of the autonomic nervous system.
The importance of vagal tone
The tone of the vagus nerve is key to activating the parasympathetic nervous system. Vagal tone is measured by tracking your heart-rate alongside your breathing rate. Your heart-rate speeds up a little when you breathe in, and slows down a little when you breathe out. The bigger the difference between your inhalation heart-rate and your exhalation heart-rate, the higher your vagal tone. Higher vagal tone means that your body can relax faster after stress.
High vagal tone is associated with:
- better blood sugar regulation
- reduced risk of stroke and cardiovascular disease
- lower blood pressure
- improved digestion
- reduced migraines
- better mood, less anxiety and more stress resilience
Low vagal tone is associated with:
- cardiovascular conditions and stroke
- chronic fatigue syndrome
- cognitive impairment
- significantly higher rates of inflammatory conditions (autoimmune disease, endometriosis, inflammatory bowel disease, etc.).
Many of the common features of PCOS, especially central obesity and high insulin levels are associated with chronic sympathetic over activity (1,2,3,4). PCOS is a state of excitation of the sympathetic nervous system which may be relevant for the cardiovascular, metabolic and reproductive consequences of the syndrome.
Symptoms of an over active sympathetic nervous system include palpitations, high blood pressure, anxiety, insomnia, nervousness, inability to relax, poor digestion, and high cholesterol among others.
As women with PCOS have significantly higher sympathetic nerve activity, this may be associated with hormonal and metabolic features that may be relevant to the pathophysiology of the syndrome. (1,3)
Can we treat PCOS by increasing vagal tone?
If women with PCOS have an overactive sympathetic nervous system, taking steps to increase parasympathetic activity via the vagus nerve could improve ovarian function. In fact, in one animal study, cutting the vagus nerve and blocking communication between the brain and ovaries, normal ovarian function was restored (5). A more practical solution is to activate the parasympathetic nervous system by increasing vagal tone.
Steps to increase vagal tone
1) Slow, rhythmic, diaphragmatic breathing. Breathing from your diaphragm, rather than shallowly from the top of the lungs stimulates and tones the vagus nerve.
2) Humming. Since the vagus nerve is connected to the vocal cords, humming mechanically stimulates it. You can hum a song, or even better repeat the sound ‘OM’.
3) Speaking. Similarly speaking is helpful for vagal tone, due to the connection to the vocal cords.
4) Washing your face with cold water. The mechanism here is not known, but cold water on your face stimulates the vagus nerve.
5) Meditation, especially loving kindness meditation which promotes feelings of goodwill towards yourself and others. A 2010 study by Barbara Fredrickson and Bethany Kok found that increasing positive emotions led to increased social closeness, and an improvement in vagal tone (6).
Dr. Shawna Darou is a licensed and registered Naturopathic Doctor, who graduated from the Canadian College of Naturopathic Medicine (www.ccnm.edu) at the top of her class and was the recipient of the prestigious Governor’s Medal of Excellence. Naturopathic medicine is her second career, her first being Engineering Chemistry from Queen’s University. She now uses her analytical brain and problem solving skills especially in the complicated arena of hormonal health, and in solving health puzzles.
Dr. Shawna Darou N.D. is a specialist in women’s health care and fertility who has treated thousands of women in her Toronto clinic since 2004. She is a dedicated and caring doctor with a gentle approach who is committed to the health of her patients. Dr. Darou’s is also an avid health writer, and her popular health blog can be found at http://darouwellness.com/blog-posts/
Outside of the office, Dr. Darou is the mother of two beautiful children who inspire her to evolve the medical model in order to reform healthcare for the next generation.
- Lansdown A, Rees DA. The sympathetic nervous system in polycystic ovary syndrome: a novel therapeutic target? Clin Endocrinol (Oxf). 2012 Dec;77(6):791-801.
- Sverrisdottir YB, Mogren T, Kataoka J, Janson PO, Stener-Victorin E. Is polycystic ovary syndrome associated with high sympathetic nerve activity and size at birth? Am J Physiol Endocrinol Metab, 294 (1998), pp. e576–e581
- Dag ZO, Alpua M, Turkel Y, Isik Y. Autonomic dysfunction in patients with polycystic ovary syndrome. Taiwanese Journal of Obstetrics and Gynecology. Volume 54, Issue 4, August 2015, Pages 381–384
- Hashim ZH, Hamdan FB, Al-Salihi AR. Autonomic dysfunction in women with polycystic ovary syndrome. Iran J Reprod Med Vol. 13. No. 1. pp: 27-34, January 2015.
- Linares R, Hernández D, Morán C, Chavira R, Cárdenas M, Domínguez R, Morales-Ledesma L. Unilateral or bilateral vagotomy induces ovulation in both ovaries of rats with polycystic ovarian syndrome. Reprod Biol Endocrinol. 2013 Jul 17;11:68.
- Kok, B, Fredrickson, B, Coffey, K, et al. How Positive Emotions Build Physical Health: Perceived Positive Social Connections Account for the Upward Spiral Between Positive Emotions and Vagal Tone. Psychological Science 2013 24: 1123
- Forsythe P, Bienenstock J, Kunze WA.Vagal pathways for microbiome-brain-gut axis communication. Adv Exp Med Biol. 2014;817:115-33.