There are different approaches and theories related to the nervous system that we should be aware of as we move through our yoga practice and address mental health. Below we will review what the nervous system consists of and 2 approaches (Polyvagal Theory, 3 Gunas) that help us better understand them.   

Three Nervous System States

1. First, our “fight and flight” response is our survival strategy, a response from the sympathetic nervous system. If you were going to run from tiger, for example, you want this response to save your life. When we have a fight response, we can have anger, rage, irritation, and frustration. If we are having a flight response, we can have anxiety, worry, fear, and panic. Physiologically, our blood pressure, heart rate, and adrenaline increase and it decreases digestion, pain threshold, and immune responses.

2. Second, we have a “freeze” state, our dorsal vagal state, which is our most primitive pattern, and this is also referred to as our emergency state. This means that we are completely shut down, we can feel hopeless and feel like there’s no way out. We tend to feel depressed, conserve energy, dissociate, feel overwhelmed, and feel like we can’t move forward. Physiologically, our fuel storage and insulin activity increases and our pain thresholds increase.

3. Lastly, our “rest and digest” is a response of the parasympathetic system, also known as a ventral vagal state. It is our state of safety and homeostasis. If we are in our ventral vagal state, we are grounded, mindful, joyful, curious, empathetic, and compassionate. This is the state of social engagement, where we are connected to ourselves and the world. Physiologically, digestion, resistance to infection, circulation, immune responses, and our ability to connect is improved.

How can you map your nervous system? 

1. Identify each state for you. 

Think of one word that defines each one of these states for you. The first step is identifying the word that you correlate with each of those three states. This is really important because then you’re able to recognize which state you are in and identify with it quickly. This will allow you to really tune in to your body and understand how you feel in that state, so you can help yourself get out of it.

For example, 

• Ventral vagal state (rest and digest state), you could say that you feel happy, content, joyful. etc. 

• Fight or flight state, you could use the words worried, stressed, overwhelmed, etc.

• Freeze state, you could use the words shut down, numb, hopeless, etc.

2. Identify your triggers and glimmers.

You’ll want to identify triggers for your fight/flight state as well as your freeze state. These could be things like a fight with your boss, an argument with your spouse, the death of a loved one, if someone cuts you off while driving, etc. It is whatever things that cause you to feel stressed. You want to eventually have at least one trigger, if not many, written down for each of those states.

Glimmers are the things that bring you to that optimal nervous system state. It could be something as simple as petting a dog or something bigger like going on a vacation.

Summary

Once you can identify what those states are for you, then you can recognize what your triggers and glimmers are for that state. You can really begin to make a profound difference in your nervous system state. You can take ownership of what’s happening to your body by tuning into how you feel and better understanding how to regulate your emotions and your responses to stress.

Ultimately, this is how we can begin to develop resilience. This means being able to have responded appropriately to life’s challenges, go to that fight or flight state for a short period, and then return back to your state of social engagement. To truly enjoy life, returning to your state of safety where you are mindful, grounded, and joyful, is a practice.

Information above is from "How to map your nervous system"

The three Gunas are constantly interacting with one another. We can discern hints from this interplay in various English phrases. For example, “innocent pleasure” is sattva-infused rajas. And “rabid addiction” is rajas-propelled tamas.

The Gunas are permanent in essence but their interactions are transitory. 

The mind’s psychological qualities are similarly unstable and can fluctuate quickly.

The predominant Guna of the mind acts as a lens. It affects one’s perceptions and perspective of the world. Thus, if the mind is in rajas, one will experience world events as chaotic, confusing, and demanding. They will have a strong tendency to continue to react to events in this rajasic way.

Therefore, yogis work towards self-observation and discernment. This way, one can witness and not react to the activities of the Gunas. But one must also have the inner-strength and willpower to consciously shift their thoughts and actions. Turning away from tamas and rajas and towards sattvic balance gives us a purpose.

Still, the three Gunas can each be desirable for different yogic practices. 

Sattva Guna is activated by meditation. It can turn the mind inwards to stillness and peace. Rajas is activated by pranayama and dynamic yoga asanas. The inertia of tamas is invaluable when one wants to sit still and meditate.

But one can become too attached to any of the Gunas. If one is attached to silence and lightness, it can be difficult to deal with the comings and goings of everyday life. If one’s rajas is out of balance, they can manifest in anger and combativeness. If one is overly tamasic, they may act lazy and careless.

Balance is the key to navigating the Gunas. 

Source: Yoga Practice

Tips to help you reduce specific Gunas in your life.

• Reduce Tamas, avoid tamasic foods, oversleeping, overeating, inactivity, passivity, and fearful situations. Tamasic foods include heavy meats and spoiled foods that are chemically treated, processed, or refined.

• Reduce Rajas, avoid rajasic foods, over-exercising, overwork, loud music, excessive thinking, and consuming an excessive amount of material goods. Rajasic foods include fried foods, spicy foods, and stimulants.

• Increase Sattva, reduce both rajas and tamas in your life. Eat sattvic foods and enjoy activities and environments that produce joy and positive thoughts. Sattvic foods include whole grains, legumes, fresh fruit, and vegetables.

All yogic practices are developed to create sattva in the mind and body. Thus, practicing yoga and leading a yogic lifestyle strongly cultivates one’s sattva.

But all Gunas can create attachment, thus binding oneself to one’s ego. 

Yogi goal is to cultivate sattva.

https://yogauonline.com/yoga-anatomy/autonomic-nervous-system-and-yogas-three-gunas