PHYSICAL WELLNESS

your stress + action response

SYMPATHETIC

NERVOUS SYSTEM

The sympathetic nervous system (SNS) is your body’s built-in alarm and activation system.

It’s what powers you up when something feels urgent, unsafe, or demanding — whether it's real or just perceived.

The sympathetic system is part of your autonomic nervous system, which runs behind the scenes.
Its job is to get you ready for fight, flight, or freeze — the instinctive ways your body reacts to stress.

When activated, it:

  • Increases heart rate and blood pressure

  • Speeds up breathing (shallow and fast)

  • Sends blood to muscles (for running or fighting)

  • Shuts down digestion and reproduction (not urgent in danger)

  • Heightens alertness and focus (to scan for threat)

It’s designed to protect you in short bursts, not run all day.

SYMPATHETIC NERVOUS SYSTEM BASICS

Common Terms + Simple Definitions

Here’s a mini glossary for brain-related words you’ll see throughout the site:

Sympathetic Nervous System (SNS) - The part of your nervous system that reacts to stress or danger

Fight or Flight - A survival response that makes you run, fight, or freeze

Cortisol - A long-term stress hormone — helps with energy but drains the body if always high

Adrenaline (Epinephrine) - A quick-response hormone that increases alertness and heart rate

Hypervigilance - Being stuck in high alert — scanning for threat even when safe

Dysregulation - When your stress response gets stuck “on” or doesn’t reset properly

Sympathetic Dominance - A state where the stress system overrides the calming one too often

WHAT THE SNS WORKS WITH

sympathetic nervous system + OTHER SYSTEMS

The SNS interacts with nearly every body system to prepare for survival:

  • Adrenal Glands: Release adrenaline and cortisol (stress hormones)

  • Heart + Lungs: Speed up to deliver oxygen and energy to muscles

  • Eyes + Ears: Dilate pupils, sharpen hearing — stay alert

  • Muscles: Tense and prep for action

  • Digestive Tract: Slows or halts (blood is redirected)

  • Immune System: Pauses healing in favor of fast reactions

It works like a gas pedal — designed to help you do something quickly.