The sympathetic nervous system (SNS) originates in the spinal cord. It goes into action to prepare the body for physical or mental activity. In response to a stressor, the sympathetic nervous system orchestrates what you familiarly call the fight-or-flight response. It is faster-acting than the parasympathetic system (the rest and digest system), and moves along very short, fast neurons. The SNS activates a part of the adrenal gland named the adrenal medulla, which then releases hormones into the bloodstream. These hormones activate the target muscles and glands, causing the body to speed up and become tense, as well as more alert. Functions that are not immediately essential (like the immune system) are shut down to some degree.

Upon activation of sympathetic nervous system, the body goes through a number of changes:

• The heart rate goes up
• The bronchial tubes in the long dilates
• The pupils dilate
• Muscles get tense and contracts
• The mouth gets dry due to reduction in saliva
• Digestion slows down
• More glycogen is converted to glucose

As you can see, all of these changes are designed to make you more ready to fight or run. Nonessential systems like digestion and immunity are given much lower priority, while more energy is made available to your muscles and your heart rate increases.

What is Parasympathetic Nervous System?

Before we go further, let’s talk about another system that works hand in hand with SNS in normal situation to help our body keeps its balance and tranquility. The parasympathetic nervous system works alongside SNS. Parasympathetic nervous system (PSNS), also known as rest and digest helps the body to get back to its calm state and allows it to relax and repair. Once the PSNS is activated we see:

• Increase in Saliva
• Release of digestive enzymes
• Drop in heart rate
• Constriction of the bronchial tubes in lungs
• Relaxed muscles
• Constriction of pupils
• Increase in urinary output

What causes SNS activation?

SNS is activated when we are faced with a stressor that presents an imminent physical danger. We actually see many of these changes in response to lower level stressors too. In a normal situation, every time sympathetic nervous system and parasympathetic nervous system work in harmony.  SNS helps us deal with the stressor and PSNS helps us to restore the peace.

The problem occurs when we are facing chronic stress, such as when we face multiple of the stressors listed below:  

1. Emotional stress –  loss of a loved one, divorce, loss of job, depression, bad and unhealthy relationships, etc.
2. Cognitive stress –  in summary trying to do it all and be the best at everything. Unrealistic expectations and not being happy with what you have and where you are.
3. Sensory stress – chronic pain, loud noise, constant stimulation from external sources. Examples: kids crying and yelling, constant phone ring, text messages, email alerts etc.
4. Metabolic stress – syndrome x, too much exercise, pH, abnormal blood sugar levels (i.e., hypoglycemia).
5. Toxic stress – what we come in contact within our environment. It includes things such as:  heavy metal toxicity, amalgam fillings, mercury in your food, air pollution, electrosmog, pesticides, herbicides, mold mycotoxins, disinfectants, perfume, air fresheners etc.
6. Immune stress – food allergies or sensitivities, inflammation, autoimmune disorders.
7. Endocrine and neurotransmitter stress – adrenal glands, cortisol, thyroid disorders, hormonal imbalances, menopause, andropause, insulin, dopamine, serotonin, norepinephrine, gamma-aminobutyric acid (GABA) etc.
8. Purposelessness and spiritual stress – lack of meaning and purpose in life, the inability to find gratitude, lack of love and empathy, not connected to the Universe, loss of self, materialism.
9. Infectious stress – Candida, parasites, viruses, bacteria etc.
10. Oxidative stress – veins and arteries, lack of fresh air, sleep apnea etc.
11. Energetic stress – electromagnetic fields from cell phones, electronics etc.
12. Structural stress – spine alignment, posture, TMJ, physical trauma, etc.

As you can see, this list is long and there are things that we are facing all day, every day., This means our SNS system is turned on all day. As you might recall one of the systems that slows down, while SNS is turned on, is the digestive system. So, no wonder we are seeing an increase in obesity and being overweight.

How can we help our Parasympathetic Nervous System to restore balance in our body and to deal with these stressors?

Remember, when we are experiencing one or two of the stressors listed above for a short period of time, the PNS system will help to return the body back to its calm state. The problem occurs when we are facing chronic stress.

We must turn off the sympathetic nervous system and return to parasympathetic state. We can do this by:

1. List everything that causes stress in your life. You can use the list above to help you. Deal with each one accordingly. Some are easier to avoid than others. For example, if you have high metal toxicity in your body, ask your health care provider about ways to detox your body. Get tested for food allergies and avoid foods that you are allergic to. If you are facing relationship issues, get help from a professional and try to resolve the issues. There is no shame in asking for help.
2. Get plenty of rest and sleep - this can be hard, but sleep is not optional anymore. Study after study has proven the importance of sleep in our health and well-being.
3. Be aware of your diet - you are what you eat. Too much sugar, preservatives, pesticides, food colorings, caffeine and chocolate all trigger SNS. Know what foods you are allergic to and avoid them. Make sure you are getting all the nutrition that your body needs from the right sources. Avoid pesticides, eat organic.
4. Most commonly used chemicals in household cleaning products, perfumes, air fresheners, pest controls, etc., contain harmful toxins that activate SNS. To avoid these toxins, try to use more natural cleaning products. There are many DIY recipes for making home cleaning products on web, that can be used to make natural nontoxic cleaning products. There are also many companies that offer natural nontoxic cleaning products (my favorite, which I have been using for years, is The Honest Company). 
5. It is important to exercise, but too much exercise can cause stress and hence activate SNS. Avoid intense exercise regimen that is super long.
6. Breathe and meditate - I think this one is self explanatory.
7. Get to know what calms you down. Is it gardening that helps you relax, or listening to music, or reading, etc.? Do more of what helps calm you.

Bottom line:

One of the reasons behind obesity and excess weight is overactive SNS. You can turn off SNS by turning on the PSNS.