To understand how the vagus nerve works, you broadly need to know how the autonomic nervous system functions.
The autonomic nervous system is divided into two parts that are both involved in our stress regulation: the sympathetic and the parasympathetic nervous systems. The sympathetic nervous system is activated when the body needs more power, while the parasympathetic is most active when we are resting.
When we are faced with dangerous situations, the sympathetic nervous system kicks in. Various substances and stress hormones are released and sent into the bloodstream. The body is now prepared for battle, whether the threat is a life‑threatening situation or we are worried about having missed an important meeting. The parasympathetic system, in turn, builds up our body and counteracts the effects of the sympathetic nervous system. It is needed when we need to wind down and recover.
What is the vagus nerve and what does it do? The vagus nerve is the body’s largest nerve and a signaling pathway between the brain and the internal organs. The vagus nerve activates the parasympathetic nervous system and basically works like a button you can press to reduce stress. It originates in the brain and travels down to the internal organs through the neck, chest, diaphragm, heart and lungs. Like a muscle, you can train the vagus nerve so that it becomes stronger. Increasing your vagal tone (the activity of the vagus nerve) is one of the most useful ways to quickly improve your overall well‑being. As a general rule, the higher your vagal tone, the better the body can regulate the internal systems that keep you healthy, such as the cardiovascular system, blood sugar levels and the immune system. You can stimulate the vagus nerve yourself, and thereby influence your parasympathetic activation, with breathing exercises, massage, intermittent fasting, taking omega‑3 supplements, cold/heat thermogenesis, physical exercise and more. Activities such as laughter, sex and singing also stimulate the vagus nerve and thus activate the parasympathetic nervous system.
Breathing with the diaphragm (conscious deep breathing) Consciously regulating internal bodily states (for example, actively lowering heart rate during the day with conscious breathing) increases emotional control and psychological well‑being. The principle for calming the system is to limit the number of sensory inputs (i.e. sounds, light and potentially certain smells) and use conscious breathing or body scanning (noticing body parts and bodily sensations in a gradual sequence from feet to head) as a mechanism to focus attention away from the mind. As little as 1 minute of conscious deep breathing a few times a day has been shown to have a beneficial effect on the heart‑lung system and improve parasympathetic activation.
A good breathing exercise to increase vagal tone is the following:
– breathe in and count to 5
– hold your breath and count to 5
– breathe out and count to 5
– hold your breath and count to 5
This type of rhythmic breathing stimulates your parasympathetic nervous system and lowers stress levels while increasing your vagal tone.
Cold Cold thermogenesis is the practice of exposing yourself to cold temperatures. Research has shown that it has a positive influence on health and longevity by changing gene expression and fat cells. Acute cold exposure will stimulate the vagus nerve. Activation of your sympathetic nervous system decreases as the body adapts to the cold, while activation of your parasympathetic nervous system increases. There is also a physiological change that increases testosterone, growth hormone and metabolic efficiency. If you want to start with cold thermogenesis, it is important to adapt the body to cold temperatures. Do not start by jumping straight into a cold bathtub. Instead, start by dipping your face in ice‑cold water. Then you can increase exposure by taking cold showers for 30 seconds and then slowly increasing the time.
Gut health Since digestion is largely controlled by the vagus nerve, it is affected when the nerve is not in good shape. Poor digestion is one of the body’s survival responses and a common reaction to stress. Under stress, digestion is not prioritized; instead, blood is transported to the muscles, which negatively affects digestion. The gut absorbs the nutrients we need, but at the same time it must ensure that foreign substances are not absorbed into the body but are excreted with the stool. The gut thus functions as a barrier against harmful substances. The term gut‑brain axis refers to the idea that the gut’s bacterial flora is thought to affect the gut barrier and, ultimately, brain functions.
Probiotic bacterial strains (good gut bacteria) that are found, among other things, in yogurt can improve the feedback loop in the vagus nerve and the gut‑brain axis and have been shown in studies to have antidepressant effects and improve your gut health.
Fasting is also a way to improve your gut health. It has been shown to strengthen the immune system by giving your body the chance to rest and recover (since it is not busy digesting food or defending against inflammatory agents in food). One example of intermittent fasting is, for instance, eating within an 8‑hour window per day and fasting for 16 hours. You can also try the so‑called 5:2 method, where you eat as usual for five days and have two fasting days when you eat about 600 kcal.
