Role of the Nervous System in Anxiety and Depression

 In Adolescent Therapy, Communication, Depression & Anxiety, Depression Therapy, Mental Health Therapist

How the Nervous System works in Depression and Anxiety

Have you ever been startled by a horn, a siren, or another loud noise?  Ever felt rejected by a nonresponse from a friend or family member?  Have you ever misinterpreted someone’s intention?  If you have, then you know your nervous system is working as intended.

The nervous system, which consists of the brain, the spinal cord and the nerves, is involved in every single facet of our lives.  The nervous system controls our movements (such as walking and running), as well as our speaking, swallowing, breathing, and learning.  It also controls digestion, heartbeat, and sweating.  In addition, the nervous system controls all five of our senses—sight, touch, hearing, smell, and taste.  The nervous system manages risk and helps us to calm down and feel safe in relationships (Dana, 2018).  In sum, the nervous system is involved in nearly everything, conscious and unconscious.

So how does the nervous system relate to mood issues, such as anxiety and depression?  Most specifically, the nervous system determines how we respond to threats and to safety.  If we feel threatened, our nervous system begins to mobilize resources.  This process starts with the release of adrenaline and, maybe, cortisol from the adrenal glands (Dana).  As a result, the pupils dilate and blood is sent to the muscles for instant action.

The release of adrenaline is nearly instantaneous and happens beyond our control, which is how most of the nervous system works.  It works quickly—in 1 to 2 hundredths (0.01 or 0.02) of a second—in the service of our survival.  Importantly, the nervous system reacts before the higher-level thinking parts of our brain.

Fight, Flight, or Freeze

When we feel threatened, we either fight or flee (run, flight), or, if we feel there is no way out, we freeze.  So, we say fight/ flight/ freeze nowadays as opposed to just fight or flight.  When we feel threatened, we generally get anxious (fight/flight).  When we feel trapped, like there is no way out, we get depressed (freeze).  Thus, the nervous system plays an important role in both anxiety and depression.

But what counts as a threat?  Not only things we normally think of feeling threatened by, such as an attacker or growling dog.  Other, smaller events can cause us to feel threatened.  A negative thought, a car honking, a negative or even neutral comment by a co-worker/friend, or a nonresponse from a friend can feel like threats, which activates our nervous system—before we know it.

In addition to the dilation of the pupils and sending blood to our muscles, other changes occur when the nervous system senses a threat.  When we feel threatened, our ability to hear and even to read facial expressions diminishes.  YES.  When we feel threatened, we often cannot hear others accurately or read their facial expressions accurately!  More specifically, when we feel threatened, the middle ear shifts from listening for human voices to detecting the sounds of predators and sounds of distress (Dana).

Implications for Depression/Anxiety

Deb Dana uses the analogy of a ladder (top, middle, and bottom) as a metaphor for being aware of the shifts in our nervous systems.  At the top of the ladder, we are calm and comfortable and in no way threatened by those around us.  If our nervous system perceives a threat, however, such as a siren or the beginning of an argument, then our nervous system reacts before we perceive—releasing adrenaline, dilating the pupils, sending blood to the muscles in preparation for fighting or flight, and even causing our ears to search for sounds of threat instead of the human voice.  We go down the ladder.  Once the higher-level thinking parts of our brain are able to get our anxiety under control, we go back up the ladder.

The Nervous System and Communication

So how does all this nervous system information relate to communication?  (For my blog on Communication, click here).  If we get into a discussion/argument with a partner/friend/child, we may feel threatened, which will trigger, beyond our control, the nervous system response.  Not only do we feel some anxiety and/or panic, but our hearing may be beginning to shift from discerning human voices to looking for sounds and facial expressions of threat.  Because of these changes, it is very important to understand that we cannot be sure we are accurately hearing our conversation partner.

Some Misunderstanding?

As a mental health therapist, I witness a lot of couples and parent-child dyads in which Person A does not accurately understand what Person B is saying.  In fact, misunderstanding may be more of a rule than an exception.  If we can understand the role of the nervous system and its role in fight/ flight/ freeze, we can see the nervous system reaction as normal and helpful, rather than scary.  And we can use the higher-level thinking parts of our brain to climb the ladder and begin to return toward safety.


Dana, Deb (2018). The polyvagal theory in therapy.  W. W. Norton & company: New York, N.Y.

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