[The vagus nerve is the tenth of twelve pairs of cranial nerves and is the longest in the body. In fact, the word vagus means “vagabond” in Latin, and perfectly illustrates the path of this nerve extending through various organs of the body.
The vagus nerve is born in the cranial box, exactly in the spinal cord, and falls into the neck developing on two branches and reaching the abdomen passing through the various organs along the path.
The vagus nerve intervenes in the sensitivity of the respiratory mucous membranes and transmits the rhythm, strength and frequency of breathing. It affects the pharynx, the larynx, the esophagus, the trachea and the bronchi, as well as administering nerve fibers to the heart, stomach, pancreas and liver. But it also carries out the inverse mission; that is, it receives signals from the internal organs and sends them to the brain to be processed.
Although perhaps the most interesting thing is the relationship between the vagus nerve and anxiety as it also transmits signals of nervousness or calm, anger or relaxation.
To understand the link between the vagus nerve and anxiety we need to understand that the nervous system is made up of two “opposite” systems that constantly send information to the brain.
The sympathetic nervous system prepares us for action, so it mainly feeds hormones like adrenaline and cortisol. The parasympathetic nervous system intervenes in rest and relaxation.
In practice, both systems work as accelerator and decelerator. The sympathetic nervous system accelerates and activates us as the parasympathetic nervous system helps us relax and reduce the speed, so it uses neurotransmitters such as acetylcholine, which decreases the heart rate and blood pressure so that the organs work slower.
The functions of the vagus nerve
The vagus nerve controls the parasympathetic system. It intervenes in many functions, from mouth movements to heartbeat, and likewise, when affected it can cause various symptoms. Some of the vagus nerve functions in our body are:
– It helps regulate heartbeat, controls muscle movements and maintains the pace of breathing.
– It maintains the functioning of the digestive tract, allowing the contraction of the stomach and intestine muscles to digest food.
– Facilitates relaxation after a stressful situation or indicates that we are in danger and we do not have to lower the guard.
– Send sensory information to the brain about organ status.
Vagus nerve and anxiety
When we are subjected to stressful situations, the sympathetic nervous system is activated. If the tension persists and we cannot turn off the physiological response that triggers it, it won’t pass much time before problems appear. At brain level, this involves the activation of two pathways: the hypothalamus-pituitary-adrenal axis and the brain-intestine axis.
The brain responds to stress and anxiety by increasing the production of hormones (CRFs) that travel from the hypothalamus to the pituitary gland where they induce the release of another hormone (ACTH), which in turn travels through the bloodstream to the adrenal glands to stimulate cortisol and adrenaline induction, which act as immune system suppressors and inflammatory precursors, which is why when we feel stressed and anxious we get ill easily and, ultimately, we can end up suffering from depression, a disorder which has been linked to an inflammatory brain response.
And as if that were not enough, chronic stress and anxiety cause an increase in glutamate in the brain, a neurotransmitter that, when produced in excess, causes migraine, depression and anxiety. In addition, a high level of cortisol reduces the volume of the hippocampus, the part of the brain responsible for the formation of new memories.
The involvement of the vagus nerve will lead to symptoms such as dizziness, gastrointestinal problems, arrhythmias, difficulty in breathing, and disproportionate emotional responses. In fact, as the vagus nerve is unable to activate the relaxation signal, the sympathetic nervous system keeps active, this will cause the person to respond impulsively and suffer from anxiety.
It is also curious that a study developed at the University of Miami found that the vagal tone is transmitted from mother to child. Women suffering from anxiety, depression or experiencing much anger during pregnancy had a lower vagal activity and their children also exhibited low vagal activity and lower levels of dopamine and serotonin.
3 vagal stimulation techniques: how to take care of the vagus nerve?
The vagal tone is an internal biological process that represents the activity of the vagus nerve. The increase in vagal tone activates the parasympathetic nervous system, which means that we can relax more quickly after a stressful situation and this will have a positive impact on our emotional balance and on health in general.
Exist various vagus nerve stimulation techniques:
1. Exposure to cold
It has been seen that exposure to cold activates the vagus nerve because it stimulates the cholinergic neurons crossing these innervations. In fact, an investigation conducted at the University of Oulu has revealed that regular exposure to cold helps to reduce the fight-flight response that launches the sympathetic nervous system.
It can be enough a cold shower of 30 seconds a day or a cold towel on the face. There are also those who lie down on the belly putting a cube of ice on the nape. Others prefer to drink quickly a glass of cold water.
2. Diaphragmatic breathing
Most people inhale air between 10 and 14 times per minute, which means they have a superficial breathing. The ideal would be to inhale air 6 times per minute. Therefore, another very effective vagal stimulation technique consists in breathing deeply.
The diaphragmatic breathing in particular activates the vagus nerve and the brain interprets it as it is necessary to calm down, even if the nerve has not given that order specifically. The mechanism is the same for which, if you close your eyes and make taps with your fingers on your eyelids, you will perceive short flashes of light because the brain interprets them so.
With diaphragmatic breathing, we make a deeper breathing that brings air into the lower part of the chest, using the diaphragm correctly and promoting relaxation.
3. Meditation, yoga and tai-chi
Meditation can increase the vagal tone. This has been demonstrated by researchers of the Oregon University who have seen that only five days of mindfulness meditation promote positive feelings towards oneself that cause the vagus nerve activation, while modulating the activity of the parasympathetic nervous system, a much better result than conventional relaxation techniques.
Even practices such as yoga and tai-chi are ideal for stimulating the vagus nerve. A study at Boston University has revealed that yoga increases GABA neurotransmitters, which promote the feeling of calm and serenity by helping to combat anxiety and stress. The tai-chi, on the other hand, is able to balance heart rate, which means it stimulates vagal modulation, according to researchers at the National Yang-Ming University School of Medicine.
Sources:
Streeter, C. C. et. Al. (2012) Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Medical Hypotheses; 78(5): 571-579.
Tang, Y. et. Al. (2009) Central and autonomic nervous system interaction is altered by short-term meditation. PNAS; 106(22): 8865–8870.
Mäkinen, T.M. et. Al. (2008) Autonomic nervous function during whole-body cold exposure before and after cold acclimation. Aviat Space Environ Med; 79(9): 875-882.
Fiel, T. et. Al. (2003) Pregnancy anxiety and comorbid depression and anger: Effects on the fetus and neonate. Depression and Anxiety; 17(3): 140–151.
Wan-an, L. & Cheng-Deng, K (2003) The Effect of Tai Chi Chuan on the Autonomic Nervous Modulation in Older Persons. Med Sci Sports Exerc; 35(12): 1972-1976.
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