Autonomic nervous system – essential information

Sympathetic nervous system

Known as the “fight or flight” system. It mainly handles rapid responses to danger and the processes needed for that response. Its activation triggers many effects in the body:

• increases the heart rate and the force of heart contractions so that more blood and oxygen reach the muscles and the brain. This prepares the body for emergency situations.
• raises blood pressure to prioritize delivery to the most important muscles and the brain during threat response.
• increases breathing rate so the lungs take up more oxygen to be delivered to cells by the blood. Oxygen is crucial for efficient muscle function.
• raises blood sugar (from the liver and muscle stores) to provide more energy for the body.
• pupils dilate, allowing more light into the eye, improving vision and alertness.
• enhances the sensitivity of the senses so we can better detect threats.
• inhibits digestive system function. Because blood flow is redirected toward muscles and the brain, digestion can be delayed.
• inhibits reproductive processes and sexual desire.

• increases attention and goal-directed focus so we can concentrate on dealing with the threat.

These effects are meant to prepare the organism for danger and enable rapid action. In “normal” situations the emergency is short-lived and the response subsides once the danger has passed or been resolved.

If sympathetic activation persists chronically, it can lead to chronic stress, inflammatory and autoimmune diseases, cardiovascular problems, sleep disorders and other health issues. Therefore stress management and relaxation techniques are important to regulate sympathetic activity and maintain bodily balance.

Parasympathetic nervous system

Also known as the “rest, digest, regenerate, reproduce” system. Its role is essentially the opposite of the sympathetic system: it promotes rest, digestion, regeneration and reproduction.

When the parasympathetic nervous system activates, it can bring the following benefits:

• reduces stress levels and relieves anxiety, contributing to mental calmness and emotional balance.
• can lower heart rate and normalize blood pressure. This helps maintain cardiovascular health and reduce the risk of heart disease.
• promotes restorative sleep. Improved sleep quality can enhance quality of life and provide energy for daily activities.
• enhances digestion and nutrient absorption, contributing to weight and metabolic regulation.
• supports more efficient immune function and helps regulate and reduce inflammation.
• improves respiratory function, lowers breathing rate, increases oxygenation and overall vitality.
• provides a sense of relaxation and rest, aiding physical and mental regeneration.

You should know that the sympathetic nervous system is always dominant, meaning its activity “suppresses” parasympathetic effects.
This is because survival comes first!
The main problem nowadays is that stress is almost constant. The struggle to make a living, family, workplace and environmental pressures, etc. are constant sources of stress.
Chronic stress is known to be one of the strongest disease-promoting factors, so you must pay attention to reducing stress and increasing parasympathetic activity.

How can you get information about the state of your autonomic nervous system?

You can get information about the state of your autonomic nervous system, for example, from certain Polar sports watches. Every morning they display your Nightly Recharge™ status — for this your watch must, of course, be worn on your wrist during sleep.

To evaluate recovery, it takes into account your autonomic balance (ANS charge) and sleep quality.

Sleep assessment is a classic sleep measurement, meaning it measures the quantity and quality of your sleep every night. It examines time spent resting and sleep cycles, then compares them with the previous 28 days.

The ANS charge value reflects how much your autonomic nervous system has calmed during the first 4 hours of your sleep compared to your usual level over the past 28 days. Using the optical sensor on your wrist, it measures your heart rate, heart rate variability, and breathing rate. Heart rate has the greatest influence on the value, while breathing rate has the least. The higher the ANS, the better your heart function has recovered. Increased heart rate and decreased heart rate variability indicate poor recovery. Conversely, lower heart rate and increased heart rate variability indicate good recovery.

Based on the current recovery state you also receive personalized daily tips regarding exercise, and when values are low the advice typically favors rest and improving regeneration.

You can get a Polar sports watch and expert help related to it at the Zerge.hu webstore.

Increasing parasympathetic activity

It is proven that increasing parasympathetic activity has positive effects on health, and on the well-being of both body and mind.

• Reduces stress and anxiety, which results in relaxation and calm.
• Improves sleep quality, which is important for restorative sleep. Since regenerative and self-healing processes occur during sleep, this is particularly important for overcoming illnesses and inflammations.
• Reduces inflammatory responses. It enhances immune function, helps regulate inflammatory responses and reduces chronic inflammatory conditions.
• Improves cardiovascular health by lowering heart rate and blood pressure. This has beneficial effects for heart and vascular health.

tVNS, i.e. vagus stimulation

Vagus stimulation is one of the newest medical treatment methods.

With the Nurosym device they stimulate a branch of the vagus nerve transauricularly, that is, at a specific point on the outer ear (the tragus), a method that has been proven to activate the parasympathetic nervous system.

The method is non-invasive, meaning nothing needs to be inserted into the body, no injections or surgery are required! It can be used completely risk-free in most cases.

During tVNS treatments mild electrical impulses are sent to the area around the ear where superficial branches of the vagus nerve are located. These impulses are transmitted to the main trunk of the vagus nerve, which then sends signals to the brain, activating the parasympathetic nervous system. This influences many body functions, including heart rate, breathing and digestion, and helps the body reach a relaxed state.

tVNS is a promising treatment option for many conditions. It has few contraindications, so it should not be used in the presence of an implanted pacemaker or cardioverter-defibrillator. There may be other conditions where careful consideration is warranted. Consult your treating physician and seek their opinion.

How to increase the effectiveness of tVNS

Sympathetic and parasympathetic functions cannot be activated simultaneously! They work in opposition and have opposite effects. It's like a seesaw: when one is up, the other is down.

Therefore it makes little sense to use vagus stimulation in the midst of workplace stress, during a gym session, in traffic jams, in any tense situation, or during a panic attack.

Perform stimulation when you are already ready to calm down and fall asleep. Treat before going to bed and then don’t “stir yourself up” again afterwards!

I already mentioned that the sympathetic (defend-or-flee) system is dominant over the parasympathetic. If you are under strong stress, you cannot activate the parasympathetic nervous system simply on command.

Try to reduce stress using multiple methods simultaneously. For example, relaxation techniques, meditation, yoga and breathing exercises contribute to stress reduction and increased parasympathetic activity.

Start vagus stimulation once you have managed to get rid of the acute stress and are ready to relax.

When should you do stimulation?

• Personalized timing: The optimal timing of stimulation varies by individual. For some, morning stimulation may help start the day energetically, while for others evening stimulation may aid relaxation and pre-sleep preparation.
• Consistent routine: Perform tVNS regularly, preferably every day at the same time. Consistency improves treatment effectiveness and the development of positive physiological responses.

How long should a session last?

• Session duration: Optimal duration may vary, but research generally recommends daily 15–30 minute sessions, up to 60 minutes maximum. Duration depends on stimulation intensity and the individual's response. Some people are more sensitive and achieve parasympathetic effects quickly. Others with stronger stress (high sympathetic activity) may take longer for the treatment to “break through.”
• Gradual start: If you are new to tVNS, it’s advisable to start with shorter 5–10 minute sessions and gradually increase as your body adapts to the stimulation. Mild dizziness or nausea may occur after early sessions, but these are rare and usually subside after a few treatments.

Stimulation intensity and frequency

• The impulse intensity should be high enough to be noticeable, but should not cause discomfort or pain. Gradually increasing intensity can help find the optimal balance between comfort and effectiveness.
• Treatment frequency is important. In most cases daily use is recommended, but in some cases a few sessions per week may suffice. Frequency should be tailored to individual goals and treatment response.

How long until you see effects?

You may remember Géza Hofi’s great cabaret sketch lampooning the Rákosi regime? A party official came to the pig farmer to ask how many piglets the sow would give… Well, how on earth could anyone know that in advance?

The same kind of fortune-telling applies to the question of how long it takes to activate the parasympathetic system.

I have astonishing experiences: in one case a single 5-minute treatment eliminated long-standing double vision (for professionals: an ocular symptom of myasthenia gravis).
Another user claimed they noticed no effect even after two weeks.

The truth is likely somewhere between these extremes.

For a mild or moderately severe, not-too-old problem the needed time may be shorter. For a longstanding, chronic stress problem, 1–2 treatments are certainly not enough. In such cases at least 30–60 days are usually required, even if you follow the recommendations during treatment.

If chronic stress is accompanied by other symptoms such as chronic inflammation or autoimmune disease… well, the answer is even more difficult. In such cases expecting an effect from a single intervention is unrealistic. You must treat from multiple angles, including nutrition, exercise, stress-reduction techniques and possibly temporary medications. For severe conditions, combining multiple methods (multimodal treatment) is more likely to help than a single approach.