Fight or Flight vs. Rest & Digest: The Difference Between the Sympathetic & Parasympathetic Nervous System


Fight or Flight vs. Rest & Digest: The Difference Between the Sympathetic & Parasympathetic Nervous System

Woman Relaxing with a Cup of Tea

The sympathetic (SNS) and parasympathetic (PSNS) nervous systems are channels of neurons that work hand in hand to control your physical and emotional state.

The sympathetic (SNS) and parasympathetic (PSNS) nervous systems are channels of neurons that work hand in hand to control your physical and emotional state.

Both are part of the Autonomic Nervous System, which manages your involuntary bodily functions so you don't have to worry about them.

Without it you’d have to command your heart to pump, your stomach to digest, and your sexual organs to get sexy.


 Why Should I Care?

In an ideal world, getting to know your SNS and PNS wouldn't be a high priority.

BUT, unfortunately, it's now something we need to be aware of, due to the world we live in:

A physically, chemically, and emotionally stressed-out atmosphere of constant stimulation.

The key is to make better lifestyle decisions that support our health and wellbeing.

If you’re reading this article while sipping a venti cold brew, with a mild case of the jitters and a side of anxiety, you’re probably going to want to learn about the Sympathetic Nervous System first.

The Sympathetic Nervous System

How to Avoid Becoming Bear Food

Also known as the “fight or flight” system, the SNS is made up of very short neurons that fire quickly to help you evade threats on sight. 

You know that instant freak out (read: full-blown spastic meltdown) you have in response to seeing a spider? Sometimes before you’re even conscious of seeing it? 

THAT is your SNS in action.

The electrical impulses from your SNS trigger a release of norepinephrine and adrenaline, which are responsible for, but not limited to, the following physiological reactions.

  • Increase your heart rate
  • Convert fat into fuel for your muscles
  • Restrict bodily functions that aren’t immediately required to escape 

All of which is helpful when you’re trying to outrun a bear.

Without the sympathetic nervous system, our ancestors would have been cross-legged and singing kumbaya while bears gnawed on their legs like corn on the cob.



Fight or Flight System - Bear Threat = STRESS

In our current domesticated world, we don't have nearly the same need for the SNS.

Like a bear will not chase you down on the way to work (we hope.) Yet the SNS lives on.

And, in lieu of physical threats, it responds to our mental and emotional “tigers and bears”—like angry bosses, stressful deadlines, never-ending to-do lists, 500 unread emails...the list goes on. 

Your pupils dilate, your breath quickens, your mouth dries up, and your heart wants to beat out of its chest...that’s when you know your sympathetic dominant, which isn’t exactly the coziest state.

Yet despite that, most of our modern day habits fuel the sympathetic nervous system.

  • Coffee, especially in the amount it’s now frequently consumed, is a primary offender: triggering the SNS via a chemical release of adrenaline
  • Breathing patterns are second in line: we get so focused on our tasks and screens that we hunch over and breathe shallowly and rapidly; all of which unconsciously stimulates the fight or flight option
  • Sleep deprivation does the same: your stress hormones linger and create a chronic feeling of stress or anxiety
All of which can cause a neverending flood of stress hormones, unless, of course, you know how to hack your parasympathetic nervous system.



The Parasympathetic Nervous System

How to Ensure the Survival of the Species

The parasympathetic nervous system is made up of long, slow-firing neural fibers which facilitate the process of “rest and digest.”

It’s easily the sexier of the two systems, with its main purpose being to rebuild the body and to propagate the species (that’s scientific lingo for “make babies”.)

In order to “propagate,” people have to feel comfortable and rested—the opposite of how you feel after being chased by a bear.

The PSNS controls physiological functions, such as:

  • Salivary production
  • The release of gastric juices
  • Peristaltic contractions (digestion)
  • Blood flow to sexual organs

When you’re in parasympathetic dominance, you’ll yawn, stretch, laugh, breathe slowly through the belly, etc.



Our Ancestors Did the PSNS Right

Our ancestors had nice and balanced sympathetic and parasympathetic systems.

After the hunt or chase, they naturally relaxed into restful activities and didn’t have to worry about work deadlines or which spouse had to pick up the kids from soccer that evening.

Their diets were chemical-free and anti-inflammatory.

They also got plenty of sleep—which, next to sex (they got plenty of that, too), is as parasympathetic-dominant as it gets.



PSNS in Our Fast-Paced Society Today

Flash-forward to now.

If you’re like most adults...

  • You get five to seven hours of sleep at most
  • You’re continually stressed: by politics, work, relationships, health problems, or any number of modern issues
  • And, even if you’ve consciously chosen organic foods as an adult, your system has been plagued by toxins and carcinogens for years

So, How Do I Fix My System?

With the right supplements and lifestyle changes, you can balance your autonomic nervous system and regain your health—and sanity. Luckily, most of the methods come free of charge and just require a bit of mindfulness.

  • Eating healthy
  • Getting enough sleep
  • Practicing mindfulness
  • Deep breathing exercises
  • At-home self-care practices


De-stressing your life is key to regaining parasympathetic dominance.

But if you’ve been sympathetic dominant for years—low sleep, high coffee, high stress—your body can have a difficult time transitioning back into “rest and digest” mode.

That’s where adaptogenic herbs, like ashwagandha, maca, and eleuthero, come in. 

Want to know more about adaptogens? Get all the deets on ashwagandha and maca right here on the Ora blog.