Imagine a hunter, thousands of years ago, tracking down his dinner when suddenly a tiger leaps in his path. The hunter feels an explosion of panic in his chest, like a firework that trickles from his heart to the tips of his fingers. What is happening in his body in those milliseconds of a moment? The amygdala in his brain perceive a situation of distress and sends an emergency signal to the hypothalamus. The hypothalamus sends nerve impulses to his adrenal glands to produce the hormones cortisol and epinephrine (also known as adrenaline). The epinephrine draws blood from his reproductive organs and stomach--which are clearly not in use during this life or death situation--and send it to his extremities. His heart beats rapidly to supply extra blood to his brain, which kicks his senses into high alert. With heightened hearing he detects the tiger cracking a twig on his right, so he swerves to the left. His elevated vision lets him see a vine wrapped around a palm tree ahead. The pathways in his lungs are fully dilated allowing him to outrun the tiger to the nearest tree. Cortisol pulses through his veins causing him to scurry up the tree with unusual stealth. He rips a coconut from the branch. With the excess blood in every muscles of his arm, he hurls the coconut at the tiger. The beast is knocked unconscious. The hunter stays in the tree panting for a moment, but soon knows from the pool of blood surrounding the tiger that it is safe to descend. His hypothalamus sends signals to returns his breathing and heart rate to normal.
We can learn from this story that the human body essentially has two modes of being, the sympathetic and parasympathetic mode. The sympathetic nervous system is in charge of the fight or flight response. On the contrary, the parasympathetic nervous system is in charge of resting and digesting. Unfortunately, these modes are controlled by the autonomic nervous system, which is involuntary. Yet there is a dangling vine of hope to cling to, and that vine is the vagus nerve. The vagus nerve is the tenth cranial nerve (V CN), and is the direct control center of your parasympathetic mode. It is also the longest cranial nerve, and passes through several major organs and body structures. The vagus nerve originates at the medulla oblongata at the base of the skull, runs parallel to the esophagus, between the lungs, around the heart, beside the stomach, through the intestines, and down to the reproductive region. In fact, "vagus" is the Latin word for wandering, because it wanders through the various regions of the body. Since the vagus nerve takes such a long course throughout the body, there are several practices that can stimulate the nerve and switch on your parasympathetic mode.
Meditating on calming and grounding images or mantras.
Singing or gargling causes a vibration that directly stimulates the vagus nerve.
Deep breathing that fully expands the abdomen like a balloon.
Yoga and massage have a physically calming effect on your nervous system.
Nurture your gut with fruits, vegetables, prebiotics and probiotics to prevent the growth of bacteria that produces neurotransmitters like dopamine. Dopamine will activate the sympathetic nervous system.
Manage blood pressure.
Exercise on a regular basis.
Make sure to get enough sleep at night, or else your body will compensate during the day by producing excess amounts of cortisol to keep you alert.
Consuming an excess of sugar and caffeine can also keep you in a state of fight or flight.
Avoid going long periods of time without eating or else your body will secrete sympathetic hormones to keep your body running--however, in an anxious state.
The sympathetic nervous system was designed as an "on" switch for our survival instincts. Yet so often nowadays the switch gets jammed in the "on" position, leaving us in a constant state of stress and anxiety. Incorporating these tips into your daily routine can help you regulate your sympathetic and parasympathetic nervous systems to function as they were intended to.