The Stress System

The stress system’s official name is the "autonomic nervous system," and it has two arms:

• The fast system (the "fight or flight" system, official name "sympathetic nervous system")
• The slow system (the "rest and reset" system, official name "parasympathetic nervous system")

(You won’t have to remember the technical names “sympathetic” and “parasympathetic,” but if you want to, you can keep them straight by remembering that the sympathetic system is sympathetic to your need to fight back or escape danger—or by thinking of the parasympathetic system as a parachute, something that brings you down gradually.)

The stress system uses several brain parts and organs in the body to trigger or pump out the chemicals it needs to respond to stress and threat, and to keep the body and brain in balance (a little more about these chemicals later).

For example, the “fast” system’s favorite brain part is the survival brain (led by a primitive structure deep in the brain called the amygdala).  The survival brain functions like a guard dog—not very sophisticated, but absolutely clear on its mission:  protecting you.  It’s also in charge of one of the memory systems mentioned in the earlier chapters, the one that records unconscious fragments of memory related to survival (sights, sounds, smells, emotions, etc.).

The “slow” system has several brain parts that do its calming work, including higher brain centers like the prefrontal cortex.  Located behind the forehead, the prefrontal cortex is the part that does logic and reason, considers morality, thinks through options and consequences, and comes up with effective plans.  All those skills are designed to help us reason with the growling, barking survival brain and keep it under control.

How the Stress System Works Toward Balance

If the stress system’s first job is to keep us alive, its second job is to keep itself—and us—in balance.  Many of its functions are organized around balance, including:

• The fact that the stress system has two opposite arms (the fast system and the slow system) that can balance one another out, the way your arms would balance your body if you were walking along a narrow board
• The "feedback loops" that run between the fight-or-flight chemicals and the rest-and-reset chemicals (with high levels of one kind of chemical designed to trigger the release of the opposite chemical, which then tells the first chemical to slow down)
• The fact that several brain parts know how to “talk to” the survival brain and provide more information, so it can calm down if there’s not really an emergency

Even the way we develop in early life is designed to help the stress system learn how to stay in balance.  For example:

• When a parent and a baby make long, loving eye contact with one another, it “grows” the part of the prefrontal cortex that helps us calm down and regulate the stress system.
• If the baby gets upset and the parent responds lovingly and kindly to his/her needs, the baby comes to believe that his/her little world is safe and stress isn’t permanent.
• As the baby watches the way the parent reacts to his/her stress, the baby learns how to handle stress.  If the parent handles stress well, the baby starts to learn about resilience.

Think of the way you grow strong muscles—by stressing them, then resting them, over and over again.  In the same way, our stress systems are designed to go back and forth between stress and calm, and between the fast system and the slow system.  It’s usually that back-and-forth motion that helps us grow strong and resilient stress systems, so we can handle stress and return to balance quickly.  Many people who have strong resilience skills learned them as they were growing up, often by going back and forth between high-stress and low-stress experiences.

Of course, not all babies get that kind, consistent attention from caregivers, and not all children grow up in situations where they have the luxury of going back and forth between mild stress and calm.  Many of us grow up in situations that fail to provide a lot of the conditions that help us grow healthy and resilient stress systems—even if parents truly love their children and try to do the best for them.

Many children find resilience wherever they can, and practice the skills of resilience without even knowing that's what they're doing.  Even so, many of us enter the adult years with stress systems that have been taught to overreact—make us "come out swinging," run away, "shut down," or "freeze" under stress and threat.

The Brain Under Stress and Threat

When there’s only mild or moderate stress or threat—and it doesn’t last too long—the fast system and the slow system play well together.  That’s what our bodies were designed to do.

But if the threat is extreme or long lasting, the survival brain takes over and refuses to listen to anyone else.  It blows through all the feedback loops that are supposed to keep things in balance.  It just wants to keep pumping a lot of adrenaline and other fight-or-flight chemicals, and store intense memories of threat and pain, so it can pull them out later and warn you if the danger seems to be returning.  It just wants to protect you, and this is its best shot at it.

Meanwhile, the slow-down system just wants to send out chemicals that will shut you down, numb you out, and keep you from making conscious memories of what’s happening.  Some of these chemicals can be just as powerful as the speed-up chemicals sent out by the fast system.

And what if the threat is intense, but the situation doesn’t give you a chance to react in the fight-or-flight way your survival brain wants you to react?  Sometimes, when the situation adds that element of helplessness, the speed-up and slow-down systems can both go into overdrive at once, and you can experience something called a “freeze response.”  This is an ancient, automatic response from the most primitive part of the brain, designed to slow your breathing and heart rate way down, and lower your body temperature, so a potential predator will think you’re dead and lose interest in you.  Have you ever seen this happen?  

The freeze response might just last a second, because many of us have been well trained to take action in a crisis.  But the freeze often tenses the front core and hip muscles (the muscles joining the abdomen and the hips).  Some experts (Peter Levine, for example) believe that the freeze experience leaves a lot of tension behind in these and other muscles, and that survival-based memories are stored in the brain’s relationship with these muscles.

Even one threatening event—like a car crash—can put your stress system in overdrive and affect the way it works for a long time.  If the threat happens over and over for months or years, it’s no wonder many people’s stress systems go out of balance.

Brain Chemicals Under Stress and Threat

It helps to think of the stress system chemicals in three categories:  chemicals that speed you up, chemicals that slow you down, and chemicals that ease the pain.

• Fast system (fight-or-flight) chemicals:  If you’ve ever been in a crisis or a very tense situation, you already know what these are like—the racing heartbeat, the pounding of blood in your head, the increase in physical strength, the overwhelming urge to take physical action.  The most important of these chemicals is adrenaline.  Just enough of this chemical makes you alert and decisive.  Too much, and you get what’s sometimes called “adrenaline overload.”  You lose touch with your higher, more rational brain, and you tend to make decisions that can backfire on you.  Another speed-up chemical is dopamine.  Dopamine makes you think quickly, feel confident, and feel very good.  These chemicals can also give you a “rush.”  People can get “addicted’ to stress and danger.
• Slow system (rest-and-reset) chemicals that slow you down:  A couple of these are most important.  Cortisol can slow down your stress system, but it can also make you anxious.  Cortisol helps protect you during the first half hour of a crisis, but after that, having a lot of cortisol isn’t good for your body—and it stays there a long time.  Long-term stress can give you too much cortisol.  Serotonin is another important slow-down chemical, helping you feel calm, think of solutions, cooperate with others, and resist counterproductive urges.  Serotonin helps protect you from difficult reactions to stress, threat, and trauma.
• Slow system chemicals that ease the pain:  The most common of these chemicals are the endorphins, the body’s natural pain relievers.  These are the same chemicals that can kick in when you’ve been doing heavy physical exercise for a while (sometimes they call this “runner’s high”).  When you’re in pain, your body sends endorphins to your brain.  It makes you less aware of the pain and helps you feel detached or separate from the situation.  If you have enough endorphins, they can join forces with cortisol to keep the conscious memory system from recording memories of the event.  But they don’t keep the survival brain from recording intense fragments of unconscious emotional memory.  That’s how you get the unconscious memories without the conscious ones.

So what do you do with all this?  How can you learn to manage all these reactions?

• For information on things you can do, see the page called What is Resilience?
  
• For information on the kinds of professional help or resilience skill training that might be available, see Help and Training in Managing Reactions.
• For more information on stress, trauma, and the memory, see How Memory Works in Trauma.
• For information on the kinds of professional services that might help you heal the effects of trauma on memory, see Changing the Way the Body Handles Memories.
  

(Page taken from The Power and Price of Survival:  Understanding Resilience, Stress, and Trauma, Copyright 2009, Pamela Woll.)