Informational Article: Hyperarousal & Hypoarousal

Hyper and hypoarousal are the two dysregulated states of the autonomic nervous system. These states are connected to the Fight-Flight-Freeze-Fawn/Fold response. “Fight & Flight” are states of hyperarousal, “Freeze” is a split response and “Fawn/Fold” is a state of hypoarousal.

Arousal refers to the level of stress and type of activity our central nervous system is under. It describes the way these reactions affect our physiological states, affective state, social function and neurological function.

Hyperarousal is an extreme state of stress that is congruous with the Fight or Flight response and some aspects of Freeze. Our brain-body system is running on overdrive, and we are seeking out active ways to handle our situation. Hypoarousal is the opposite, our brain-body system is running low, and we experience a level of a shutdown. This is connected to the fawn/fold responses.

When looking at trauma this is important to understand as arousal and nervous dysregulation is a symptom of (C)PTSD and key to how trauma affects us in our lives. Childhood trauma especially can leave people with an inability to healthily shift between arousal states. Healthy arousal levels are important in maintaining physical and psychological health.

When we cannot regulate our nervous system we are locked in either hyper or hypoarousal. This leaves us with persistent stress and when presented with stressful stimulation we cannot process it. It also leaves us open to re-traumatization when higher stressors are present.


A graph of the human nervous system. A human outline with the central nervous system and peripheral nervous system labelled. Two the right of that are two rectangles labelled parasympathetic nerves and sympathetic nerves. In each of these blocks are the organs affected by these nerves and how they are. Parasympathetic block: constrict pupils, stimulate saliva, constrict airways, slow heartbeat, stimulate activity in the stomach, inhibit glucose production, stimulate the gallbladder, stimulate the activity of intestines, contract bladder, promote the erection of genitals. Sympathetic block: dilate pupils, inhibit salivation, relax airways, increase heartbeat, inhibit the activity of the stomach, stimulate the release of glucose, inhibit gallbladder, inhibit the activity of intestines, relax the bladder, and promote ejaculation and vaginal contractions. In between the two blocks is a model of the brain, spinal cord and sympathetic chain. The vertebrae are labelled. End
Overview of the nervous system

Arousal is controlled by the amygdala, hypothalamus, autonomic nervous system, endocrine system (specifically the pituitary gland).

  • The amygdala & pituitary gland start the stress response in tandem with the wider endocrine system. The hormones/neurotransmitters involved are cortisol, norepinephrine and adrenaline. 
  • The hypothalamus connects the brain and pituitary gland to the rest of the central nervous system. It is key in the regulation of much of the autonomic functions and during stress periods is activated to effect function like heart rate. 
  • Within the autonomic nervous system, the two main branches are parasympathetic and sympathetic (Sympathetic activates and parasympathetic deactivates ). The nerves important here are cranial (primarily the vagus & ventral cluster), enteric nervous system, and spinal nerves.

Normally Hyperarousal is triggered by an outside stimulus experienced by the peripheral nervous system, sent through the central nervous system and into the brain. Then the cascade of the sympathetic response and you make it through whatever was causing this extreme response. Then this energy should discharge and slowly bring the body back to normal arousal by the parasympathetic nervous system response. However, when trauma happens the later part of the discharge and regulation is interrupted.

The inability to move out of the hyperaroused state it causes overproduction and build-up of the neurochemicals of cortisol and norepinephrine. The brain is now dealing with trauma and causes the brain structures to be damaged, and in developmental trauma, this is more pronounced.

The major regions of the brain that trauma affects include the hippocampus, amygdala, and ventromedial prefrontal cortex. The structure, shape and size are markedly different to non-traumatized individuals. The connections between these areas of the brain become distorted so information and stimuli can become warped during the brain’s normal functions. The connection of the right and left brain can be damaged as well. In those who have these traumas, their brains and bodies are left dysregulated and lead to being always in either hyper or hypoarousal.

Models of Arousal

Let’s go through a few models that describe the scale of arousal we go through and can help us understand where we are and how it relates to stress and trauma.

1-10 arousal scale:

This model goes through the basic emotional and physiological feelings we experience and which of the fight-flight-freeze-fawn/fold responses we might be in.

1-3: Hypoarousal/Very Low Arousal

  • Brain fog
  • Connected to feelings of hopelessness and shame
  • Covert response to trauma, usually not noticed by outsiders
  • Depersonalization & derealization 
  • Difficulty making decisions
  • Difficulties with focus
  • Disruption of the locus control 
  • Dissociative symptoms
  • Dizziness
  • Emotional numbing
  • Exhaustion and Fatigue
  • Hypotension 
  • Headaches and nausea
  • Part of the fawn, fold & freeze responses
  • Passive to outside input and/or hyper compliance
  • Shallow breathing and possible a low respiration rate
  • Triggered by feelings of overwhelm, terror, helplessness and loss of control

4-7: Regulated State/Optimal Arousal

  • Able to adapt and change with the situation
  • Able to breathe diaphragmatically 
  • Able to focus and plan
  • Able to recognize emotions and use rational thinking at the same time
  • Can be embodied
  • Emotions can shift in intensity but never reach a point where we become overwhelmed
  • Low muscle tension
  • Present and able to interact with others
  • Stable blood pressure
  • Stable resting rate and will raise and lower with exercise

8-10: Hyperarousal/Extreme Arousal

  • Agitation
  • Breathing can become faster and experience hyperventilation 
  • Can experience a “one-track mind”
  • Chronic Pain, often muscular-skeletal pain
  • Defensive postures and thought patterns
  • Emotions feel like they are on hyper-drive
  • Fear, anxiety & shame common
  • Heart rate high
  • High muscle tension
  • Hypertension
  • Impulsivity
  • Sensory overload common
  • Related to Fight, Flight and Freeze
  • Restlessness 

Sequence Model:

The Next Model follows a 1-7 labelling process and describes the patterns of how we shift between them. It can also help us understand how trauma and extreme stress are needed for the dissociative states. This model also breaks down the fight-flight-freeze-fold/fawn states related to more general arousal states.

  1. Arrest & Alert: Associated with curiosity. A state of arousal where our thoughts can wonder if we are open and able to think clearly but aren’t focused.
  2. Stiffen & Orient: Associated with focused attention, interest and preparedness.
  3. Asses: Associated with intense interest, friendliness or repulsion.
  4. Approach or avoid: Associated with pleasure and displeasure. When here we get that instinctual need to either involve yourself in an experience or to leave. This is the first time we see a split in the responses to stress. Our nervous system acts on these instincts. We can start to have involuntary movement, but there is still involvement of the higher brain and control. 
  5. Fight-or-Flight: This is where we start to experience intense activation of our nervous system and when we hit this point on the continuum we are in a survival state. Fight-or-Flight leaves us in a state of fear or anger. 
  6. Freeze: We experience this generally when Fight-or-Flight is not effective and that pattern is thwarted. When we freeze our emotional state is usually one of terror to the point our body locks up. 
  7. Fold/Fawn & collapse: Our nervous system collapses, and we are feeling helpless to escape a threat.

*note depending on stimuli that are acting as a stressor you may not truly experience fight-flight and automatically freeze or if you’ve experienced trauma that left you dissociated you might automatically fawn/fold.

5-7 are the emergency survival states and our implicit procedural memories become activated and the conscious thoughts take a back seat to subconscious involuntary processes. We move from awareness of danger and fear to outright terror and ending with the most basic and last-ditch survival mode of collapse.

Specific Autonomic Nervous System Reactions.

Phase 5: The fight-flight response is associated with the sympathetic nervous system and the endocrine system, specifically adrenal glands. This arousal level gets us ready to mobilize and meet the threat. Our muscles get ready to move and our minds try to figure out how to leave or fight the threat. Because our body is trying to escape physically and survive. Our body suspends the digestive system and prioritizes activation of the cardio-pulmonary system muscular activation. Our mind tries to take in our environment via our sensory systems (sound, sight, etc) and plan how best to get away from or stop the threat. Other thought processes shut down and the memory encoding system is affected. This is a hyperarousal state

If the threat is not resolved, and we have not escaped, we move out of phase 5 into phase 6, freeze. When we get here our sympathetic nervous system intensifies the hormone and neurotransmitter cascade. This level of activation keeps the body on high alert, but because we can’t fight or escape, our muscles clam up and our brain stops trying to take in our environment or plan an escape. We lose our ability to react. The memory encoding worsens and dissociation starts to intensify. Phase 6 is an overlap of hyper & hypoarousal.

If we start to believe we are in mortal danger or the threat is continuous and inescapable we move into phase 7: fawn and fold. Dissociation becomes extreme and everything starts to collapse including our; metabolism, memory, respiration, circulation, digestion and we become exhausted. We can either fold into ourselves enough that we might stay frozen or we may become hyper-compliant to the person who is hurting us or the activities we are forced to do. Implicit memories are strong here. The key to phase 7 is our minds and bodies have ceased trying to process the world outside and suspend some functions of homeostasis.

The shutdown process is controlled by the parasympathetic nervous system via the vagus nerve. The parasympathetic response is more intense than normal and due to the situation, the sympathetic response has not been able to ebb naturally. This can leave our internal feelings and physiological reactions disconnected and contradictory inside of us.

Phase 7 is the state of trauma and causes most of the long term damage. States 5 & 6 are part of trauma and will continue to be experienced but, stage 7 will always leave us traumatized. Stage 7 is the essence of trauma, the inability to move out of stress and helplessness. It is also the state that facilitates the fragmentation of self as it’s the strongest dissociative response and the split of the physiological process.

Window of Tolerance:

The “Window of Tolerance” is the zone of arousal where we can manage and thrive in everyday life. The window of tolerance will include different levels of outside stressors and a range of experiences positive, neutral and negative.

Inside our window of tolerance, we can stay regulated and interact with others. This regulated state is referred to as “optimal Arousal”, healthy arousal or the Ventral Vagal state. Our emotional and logical brains work in tandem, we are capable of self-reflection, social engagement and to make plans. Our emotions are proportionate to the situations and we can handle them properly. Being able to move and adjust to the situation is the hallmark of being within our window of tolerance.

When we are outside of our window of tolerance, our nervous system is dysregulated. We become unable to properly process the situation and experience such overwhelming stress we shift into hyperarousal or hypoarousal.

Our window of tolerance can be narrow or wide and is different for all people. The size of our window of tolerance is affected by; breadth experience, age, health, attachment and trauma history. A wide window of tolerance means we are capable of coping with more types of stress and can experience more intense emotions without losing our ability to cope and keep our physiology within a healthy state.

For example, a young child can easily be outside of their window of tolerance because they might not have ever fallen off a bicycle before and become upset where an older child will be able to shake it off. Or looking at school some people’s window of tolerance and life experience might make a test an important event but something they can deal with by taking a nap after while this might be outside another student’s tolerance and they could experience a panic attack.

Everyone will end up outside our window of tolerance, there will always be events people can not process. And they should not be expected to, but having a wider window of tolerance is a sign of being healthy. When we can regulate and cope we feel more stable and can interact with others in a manner that brings health.

A small window of tolerance reflects an inability to self or co-regulate. It’s not a personal failing, if we are traumatized we can more easily fall out of a healthy arousal state. If we flip between being hypo and hyper-aroused it can make us feel unstable, interrupt our ability to handle daily life, impact relationships and have negative implications on our health. Overtime developing a wide window of tolerance is important to living a full life and is part of how we build our resilience.


Traumatization occurs when an event causes our nervous system to be out of balance, our mind is unable to process the event, and we cannot discharge the stress. Trauma is carried in the unconscious mind and nervous system. This is what we mean by the body carrying trauma, and this factor of hyper and hypoarousal is one of the ways this is expressed along with the structural and chemical changes.

A blue diagram is titled "Symptoms of undischarged traumatic stress" in black text. In the centre is black two parallel dashed lines. The space between is labelled: "normal range" and a grey wave runs in the normal range. On the left of the top line is a lighting bolt is labelled "traumatic event". A line comes in and out of the normal range. The space above the normal range image is a red box with black text reading "stuck on on." Below the normal range image is a grey box with black text reading "stuck on-off". A red square on the top right contains the text: "anxiety panic, hyperactivity, exaggerated startle, inability to relax, restlessness, hyper-vigilance, digestive problems, emotional flooding, chronic pain, insomnia & hostility/rape". On the bottom left is another square containing the text: "Depression, flat affect, lethargy, deadness, exhaustion, chronic fatigue, disorientation, dissociation, dissociation, complex syndromes, pain, low blood pressure and poor digestion." End
Traumatic event affects the regulation of arousal.
Levine, Ogden, Siegel

Pervasive States

When we are traumatized and our body cannot move out of the dysregulated states of hyper or hypoarousal and end up locked into these dysregulated positions. We will likely switch to other extremes but will spend little to no time in a state of calm.

These pervasive states can be less extreme than the complete physical freeze, fight, flight or fold, but it is experienced with most of the same emotional and physiological expression. However, when experiencing these chronic states of hyper and hypoarousal we can easily be thrown into an extreme episode of anxiety, flashbacks, dissociation and panic.

Pervasive hyperarousal is characterized by excessive activation via a hyperactive amygdala and sympathetic nervous responses. This can be experienced as anxiety, panic attacks, fear, paranoid thoughts, hypervigilance, and overwhelming emotions. We can feel unsafe and continually feel like we need to search for threats. Another common feeling is that we have a ball of energy sitting inside and experience a need to act.

Chronic hyperarousal impacts our ability to relax, focus, sleep, eat, relate to others, digest food, and manage our emotions. This feeds risky behaviours to try and discharge energy. Addiction can also be common in an attempt to regulate and deal with intense emotions. Social interactions can be damaged by our agitation, anxiety or lashing out. Dissociative states can occur in dissonance with emotions. We can drop into hypoarousal as our body runs out of energy and collapses into fatigue. This is present in all trauma disorders.

Pervasive hypoarousal is experienced when our parasympathetic response is locked in while also experiencing stress hormones. We are unable to reach the level of physiological and neurological activation to interact with others and self in a normal way. This is characterized by exhaustion, hypersomnia, depression, flat affect, numbness, disconnection, Dr: Dp, dissociation, brain fog, memory dysfunction and emotional confusion. It impacts our executive function, ability to make choices, digest food, feel or process sensory and somatic experiences.

Long term hypoarousal is often experienced in cycles with hyperarousal, for many, it can happen connected to triggers of dissociation or fatigue after hyperarousal. Hypoarousal is near-constant for those who have chronic dissociation. Those with C-PTSD and especially dissociative disorders (DID & OSDD) will experience long term hypoarousal. Social engagement is disrupted by feeling disconnected and struggling to interact, a possible complete lack of reaction to others and/or episodes of hyper compliance..

Something to remember is that those of us who spend time in the two extremes we can move between them for many different reasons. And there is no length of time anyone has to stay in either state and we can go through them throughout the day based on outside stressors, reminders of trauma and health factors.

Pervasive states are also connected to implicit memories emotionally and procedural memories. Implicit and procedural memories developed during trauma are formed due to survival and will reinforce learned behaviours that act in states of hyper or hypoarousal. Both the memory and arousal patterns are key functions of trauma as both keep you living in a traumatized state.

Flashbacks also support these patterns of arousal as they put the body through the visceral memories of trauma and produce the hormone cascades and nervous system responses experienced during the trauma. Being in states of hyperarousal predisposes people to experience triggers harshly making flashbacks more common along with panic and anxiety attacks. Dissociative symptoms of hypoarousal worsen the experience of things like somatic flashbacks as they are key to their formation.


Understanding these states of arousal are important to understand what dysregulation is, how we become traumatized, why we react to stressors the way we do, our pervasive emotional states, the long term effects of trauma and gives us language to explain the collections of symptoms. Arousal theory is a strong connection to understand the neurobiological and physiological knowledge and personal experience.

Arousal is part of how we carry trauma in our bodies why trauma affects every part of our organ and emotional experiences. When we know this it can help us understand why we need somatic, physical and attachment-based healing so we can integrate our trauma and become embodied.

Language and knowledge are key. When we can understand how our bodies and minds are reacting and carrying the experiences with us we can connect with our full self.


  1. Ogden, P., Minton, K., and Pain, C. (2006). Trauma and the body: A sensorimotor approach to psychotherapy. New York: Norton.
  2. Siegel, D.J. (1999). The developing mind: How relationships and the brain interact to shape who we are. New York; Guilford Press.
  3. Segal, Z. V., Williams, J. M. G., & Teasdale, J. D. (2013). Mindfulness-based cognitive therapy for depression: A new approach to preventing relapse. 2nd Edition. New York: Guilford Press.
  4. Young, Adam. 20 Aug. 2018,
  5. Gill, Lori. “Understanding and Working with the Window of Tolerance.” Attachment and Trauma Treatment Centre for Healing (ATTCH), 25 Nov. 2017

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