The causes of an increase in parasympathetic activity are deep breathing exercises, positive emotions, and certain types of physical activity.
An increase in parasympathetic activity can also be a reflex response to elevated blood pressure.
When you have and experience positive emotions, like joy or happiness it can result in an increase in your parasympathetic nervous system activity.
Doing deep breathing exercises, including box breathing, where you inhale 4, hold 4, exhale 4, hold 4, can also stimulate your vagus nerve, which is a key component of your parasympathetic nervous system.
Intense exercise can also initially activate your sympathetic nervous system, "Fight or flight", although activities such as tai chi, yoga and gentle stretching can promote parasympathetic activity as your body relaxes and recovers.
And an increase in your blood pressure also triggers baroreceptors which are pressure sensors in your arteries and these receptors send signals to your medulla in your brainstem, which then reduces sympathetic activity and increases parasympathetic activity to lower your blood pressure.
The symptoms of parasympathetic overstimulation are dizziness, brain fog, fainting, digestive issues such as diarrhea and nausea and even low blood pressure, or bradycardia and in some cases difficulty breathing, general malaise and increased sweating.
Parasympathetic overstimulation is also called dysautonomnia or vagal overstimulation.
The 5 effects when the parasympathetic nervous system is stimulated are promotion of urination and defecation, increasing mucous production and salivation, stimulating digestion, constricting pupils and slowing heart rate.
Your parasympathetic nervous system slows down your heart rate and reduces the force of contractions, which helps to conserve energy and return your body to a resting state.
When your parasympathetic nervous system is stimulated it also causes your pupils to constrict and reduces the amount of light that enters your eyes, which is also useful in low light and relaxed environments.
Your parasympathetic system also promotes digestion by increasing the activity of your stomach and intestines, including increased peristalsis, "Muscle contractions that move food".
Your parasympathetic nervous system also stimulates your salivary glands to produce saliva and your mucous membranes to produce mucus, which also aids in digestion and protects your respiratory system and it also relaxes the muscles involved in defecation and urination and allows your body to eliminate waste products.
The symptoms of an overactive vagus nerve are insomnia, headaches, digestive issues, fatigue and even fainting spells.
Overactive vagus nerve is also called parasympathetic excess or even vagal excess.
Your vagus nerve is associated with relation and digestion, although when your vagus nerve is overactive it can disrupt the normal functions can cause several health issues.
Your vagus nerve is the longest cranial nerve, which extends from your brainstem, down to your abdomen.
The vagus nerve plays a critical role in regulation of various bodily functions, which include breathing, mood, digestion and heart rate.
The vagus nerve is also part of your parasympathetic nervous system, and is responsible for the "rest and digest" response.
Common symptoms of an overactive vagus nerve are fainting, dizziness, changes in heart rate or blood pressure and lightheadedness, abdominal pain, nausea, bloating, vomiting, difficulty swallowing and acid reflux, fatigue, insomnia, headaches, hoarseness and even other symptoms that are similar to fibromyalgia.
The causes of an overactive vagus nerve are vasovagal syncope, chronic vagal excess, certain medications, neck instability, and other underlying conditions such as anxiety, depression and digestive issues.
Issues in your neck, like ligamentous laxity can irritate your vagus nerve and cause symptoms of an overactive vagus nerve.
Some people also have a chronically dominant parasympathetic nervous system, which can lead to persistent symptoms of overactive vagus nerve and a temporary overstimulation of your vagus nerve can cause a sudden drop in your blood pressure and heart rate, which leads to fainting.