The Three Phases Of Chronic Stress - Neuropedia

The Three Phases Of Chronic Stress

It happens to every single person. You’re humming along in your day, and then bam— a stressor enters your awareness, and you’ve become completely hijacked. The stress response can sometimes make you feel like you have no control over your environment.

Why? Because the complex cascade of chemicals that are meant to keep you alive are all-encompassing and they do, quite literally, hijack your brain.

It may seem unfair and unnecessary that a stressful call from a family member or colleague should throw your entire day off track, but from a primitive perspective, your reaction is the appropriate response.

Why Stress Can Make You Feel Like The World Is Crumbling

Logically, you know that your upcoming meeting or your long to-do list isn’t going to kill you. So why does it feel like these common stressors are larger than life when they take over?

To answer this question, we have to take a journey back in time.

First, it’s essential to understand that your stress response activates the most ancient structure in your brain— the amygdala. This means that way before humans were able to think logically and analyze (and overanalyze), they were able to perceive stress.

For your ancient ancestors, stressful events weren’t quite as complex as what you deal with today. For instance, something that might have stressed out an early human would be a real threat to their life— like a circling tiger that’s hungry for dinner. In this situation, taking a moment to breathe and choose the appropriate response would be taking one moment too long. They didn’t have the luxury of mindful awareness under stress. They had to fight or flee.

Unfortunately, the brain structures that recognized stress for your ancestors haven’t been updated to understand the consequences of the “stress” we experience today. Therefore, when you perceive stress (such as a large electrical bill, an aggravating encounter, or feeling overwhelmed at work), your body behaves like there are a bunch of hungry tigers in your living room.

What exactly is happening in your body? The stress response generally occurs in three phases, which we’ll break down in the next section.

The Three Phases Of The Stress Response

The stress response involves a complex coordination of neurological and physical activity that can be generally broken down into these three phases:

Phase 1: SAM (Sympathetic-Adreno-Medullar) Activation

SAM (Sympathetic-Adreno-Medullar) activation is the first phase of the stress response. This system is incredibly fast-acting and happens below your conscious awareness.

When SAM is activated, it increases the initial feelings of alertness, vigilance, and appraisal of the situation. This response is short-lasting, but it is meant to enable a strategic decision as to how to act in the face of your stress trigger.

Have you ever heard a loud noise outside that made you jump out of your seat? Where are you going? You have no clue. There was just something in your brain that immediately alerted your body “Get up! Go!” This is your SAM at work.

SAM becomes activated when a stressful trigger enters your awareness. You take in this information via your senses (sight, sound, smell, touch), and it immediately sends a message to your amygdala (the ancient brain structure involved in your stress response). Your amygdala then sends a distress signal to your hypothalamus.[1][2]

Your hypothalamus is a command center in your brain that communicates with the rest of your body via your autonomic nervous system (ANS). In the case of a stress response, your hypothalamus activates the sympathetic branch of your nervous system (AKA fight or flight response.

Sympathetic activation is carried out by signals sent from your hypothalamus to your adrenal glands. Once your adrenal glands get the message that danger is afoot, they release epinephrine (adrenaline) into your bloodstream, resulting in:[3]

  • Increased heart rate
  • Increased blood flow to muscles
  • Increased blood pressure
  • Rapid breathing
  • Increased oxygen capacity in the lungs
  • Increased oxygenation of the brain
  • Enhanced senses (sharper eyesight, hearing, etc.)
  • Enhanced alertness
  • Release of energy into the bloodstream (glucose)

All of these physiological changes happen to help you fight or flee from the impending danger. And it all happens within seconds, often before your logical brain can even catch up with what’s happening.

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Phase 2: HPA (Hypothalamic Pituitary Adrenal Axis)

As mentioned, SAM is incredibly fast-acting, but it is also short-lived. As the initial activation of your stress response from SAM starts to die down, the HPA axis comes in to carry you through phase two.

Your HPA axis is able to keep your sympathetic activation going for a longer period of time and acts through a complex series of signals that involves your hypothalamus, pituitary gland, and adrenals.[4]

Specifically, your hypothalamus begins to call on your pituitary gland by releasing corticotropin-releasing hormone (CRH). Your pituitary gland then releases adrenocorticotropic hormone (ACTH) in response to the distress call from your hypothalamus, which signals your adrenal glands to secrete glucocorticoids (cortisol).[5]

In this way, one of the primary differences between SAM and your HPA axis is that SAM results in the release of epinephrine, while the HPA axis results in the release of cortisol. Epinephrine is shorter lasting, while cortisol tends to stick around longer.

Phase 3: Chronic Stress Activation

While your ancestors surely had much more serious concerns to deal with when they were living in the wild, for some reason, life seems more stressful than ever these days. This is primarily due to an overactive stress response that doesn’t resolve as fast as it would if it were just tigers that we were running from. As scary as that sounds, once the tiger is gone, the stress is gone.

Today, the tigers like to stick around, and our analytical brain loves to mull over all the ways the “tigers” could destroy us. This leads to chronic stress.

Chronic stress keeps your HPA axis active and therefore keeps your cortisol flowing. This overactivation of the sympathetic nervous system can lead to a range of health problems.

In fact, research shows that early childhood events that create a chronic stress response may result in a two- to three-fold higher rate of anxiety and other mood disorders into adulthood.[6]

Overactivation of the HPA axis has also been associated with immunological triggers that may increase the risk of neurological diseases like Alzheimer’s.[7]

Generally speaking, chronic stress is associated with increased systemic inflammation, weight gain, increased risk for heart disease and dampened immune responses.[8]

Takeaway: Manage Stress Before It Manages You

Stress is a tricky adaptation for humans. While animals still have the ability to simply “shake off” stressful occurrences, humans seem to linger in a stress response much longer. Therefore, it’s in your own hands to manage your life stressors and calm your system, so the stress response doesn’t run your life.

Working with a therapist or other mental health professional may be the best way to cut through the fog that stress can create if your stress feels out of control.

However, many people find that they can get stress-relief from simple practices like:

  • Journaling
  • Yoga
  • Meditation
  • Breathwork
  • Talking with loved ones
  • Exercise

There are several supplements out there that can also impact the way your body physically and mentally handles stress. If you’re interested in finding a supplement that can support you, take this quiz to find your unique formula.

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