What are the Phases of The Fight or Flight Response?

Understanding the Fight or Flight Response

The fight or flight response is an automatic reaction to an event our brain perceives as threatening or stressful. This response activates our body’s natural defenses to enable us to respond appropriately to potential harm.

The 3 Phases of the Fight or Flight Response

There are 3 key phases our bodies go through during the fight or flight response:

Alarm reaction – The initial fight or flight response. The body experiences a burst of heightened physiological arousal and alertness.
Resistance – The body remains physiologically aroused and on high alert. This phase allows us to continue dealing with the threat.
Exhaustion – The body’s resources are depleted after remaining in an emergency state for a prolonged period. Fatigue sets in.

The Physiological Changes

During each phase, several physiological changes occur in the body to prepare us to fight or flee:

Increased heart rate, blood pressure and breathing rate
Release of stress hormones like adrenaline and cortisol
Increased sweat production to cool the body
Pupil dilation to improve vision
Diversion of blood flow toward major muscle groups

The Importance of the Parasympathetic Nervous System

After the threat passes, the parasympathetic nervous system helps return our body to normal function through:

Lowered heart rate and blood pressure
Decreased stress hormones
Increased digestion and immunity

Coping with Fight or Flight

The fight or flight response is healthy and necessary for dealing with real danger. However, this response can be repeatedly triggered by stressful situations where there is no real physical threat present. Understanding how to minimize unnecessary triggers and return to a calm state more swiftly can help prevent longer term negative impacts on health and wellbeing.

Strategies to Manage Fight or Flight

Some helpful strategies include:

Diaphragmatic breathing exercises to manually calm the body
Progressive muscle relaxation to release physical tension
Meditation and visualization to quiet the mind
Positive self-talk to challenge unhelpful thinking patterns
Spending time in nature to promote relaxation

Neurobiological Cascades: The Role of the Amygdala and Prefrontal Cortex

While the phases of the response describe the systemic output, the internal initiation is a complex neurological relay race. It begins in the amygdala, the brain’s emotional processing center, which acts as a smoke detector. When the amygdala perceives a threat—even a symbolic one like a looming work deadline—it sends an immediate distress signal to the hypothalamus. The hypothalamus functions as the command center, communicating with the rest of the body through the autonomic nervous system. Crucially, this happens faster than the prefrontal cortex, the area responsible for rational thought and executive function, can process the information. This explains why we often react before we think; the body is literally bypassing logic to prioritize survival speed. Recognizing this disconnect is the first step in regaining control, as it validates why one might feel irrational during a high-stress moment.

The Impact of Chronic Activation on Internal Systems

When the body enters the resistance phase repeatedly, it creates a state of systemic hyperarousal known as allostatic load. Unlike a short-lived burst of energy, chronic activation keeps the cardiovascular system in a state of high tension. Over time, this contributes to hypertension and arterial damage. Furthermore, the persistent elevation of cortisol—the primary stress hormone—affects metabolic health. It encourages the body to store fat, particularly in the abdominal region, and can lead to insulin resistance. Because the digestive system is effectively ‘shut down’ during the fight or flight response, individuals living in a constant state of alarm often experience gastrointestinal issues like irritable bowel syndrome (IBS), bloating, or poor nutrient absorption, as the body prioritizes muscle readiness over metabolic maintenance.

The Sensory Distortion Phenomenon

During the alarm and resistance phases, your sensory perception undergoes a radical shift known as ‘tunnel vision’ or ‘auditory exclusion.’ Because the brain is fixated on the perceived predator, it narrows its focal point. In a modern context, this might manifest as being unable to hear a colleague talking to you while you are intensely stressed about a presentation, or feeling like your peripheral vision has darkened. This is an evolutionary adaptation meant to prevent distraction. However, in a professional or social setting, this can lead to poor decision-making because you are physically unable to process the full breadth of the environment. Recognizing this sensory narrowing can serve as a ‘check-in’ signal; if you notice your world feeling smaller or your hearing feeling muffled, you are likely deep in a physiological response and need to consciously widen your focus.

Fine-Tuning the ‘Freeze’ Response

While fight and flight are the most discussed reactions, there is a third, often misunderstood component: the freeze response. This occurs when the nervous system determines that neither fighting nor fleeing is a viable option. In this state, the body experiences a paradoxical reaction: heart rate may drop suddenly, or the individual may feel physically immobilized, dissociative, or ‘numb.’ This is the body’s way of ‘playing dead’ in the face of an overwhelming threat. Understanding that ‘freezing’ is not a sign of cowardice or laziness, but rather a profound biological overwhelm, is essential for self-compassion. If you find yourself stuck or unable to move forward on a task, you may be experiencing a freeze response. Re-engaging the body through small, intentional movements—like wiggling toes or shifting weight—can often signal to the nervous system that the threat has passed and it is safe to ‘thaw.’

The Role of Vagal Tone in Recovery

The transition from the resistance phase back to homeostasis is managed largely by the vagus nerve, the primary component of the parasympathetic nervous system. Vagal tone refers to the capacity of this nerve to return the body to a calm state after a stressor. Individuals with ‘high’ vagal tone recover from stress quickly, while those with ‘low’ vagal tone may feel ‘stuck’ in a state of anxiety for hours. You can actively strengthen your vagal tone through specific behaviors. Cold exposure, such as splashing ice-cold water on your face or ending a shower with a cold blast, stimulates the vagus nerve. Similarly, rhythmic activities like chanting, humming, or deep, slow vocalizations (which stimulate the vocal cords and the muscles in the back of the throat) act as a mechanical ‘brake’ on the sympathetic nervous system, accelerating the transition out of the resistance phase.

The ‘Second Wave’ of Stress: Psychological Rumination

A major reason the exhaustion phase is reached prematurely is the phenomenon of psychological rumination. While the initial fight or flight response is triggered by a biological event, the secondary wave is triggered by our own thoughts. If we replay a stressful argument or worry about a future event, we are effectively ‘re-triggering’ the alarm phase. This creates a feedback loop where the brain cannot distinguish between the actual event and the memory of the event. To mitigate this, one must interrupt the cognitive loop. Techniques like ‘thought labeling’—where you explicitly tell yourself, ‘I am currently ruminating, this is a thought, not a current danger’—help the prefrontal cortex regain dominance over the amygdala, effectively shutting down the hormonal supply chain that keeps the body in the resistance phase.

FAQ

What triggers the fight or flight response?

The fight or flight response can be triggered by various real or perceived threats and stressors, such as confrontation, danger, public speaking, testing, deadlines, arguments, etc.

How long does the fight or flight response last?

If the triggering situation resolves quickly, the fight or flight response may only last minutes. But if the stressor persists or our thinking continues to fuel the stress response, it can last hours, days or even weeks.

Is the fight or flight response bad?

No, this response developed to help us react to and deal with threats for survival. It only becomes problematic if it is excessively or chronically triggered in the absence of real danger, leading to long-term wear and tear on the body.

What hormones are released during fight or flight?

The main hormones released are adrenaline and cortisol. Adrenaline increases heart rate, blood pressure and energy supplies, while cortisol releases glucose and suppresses non-essential functions.

How can I calm my fight or flight response?

Strategies to calm fight or flight include slow breathing, muscle relaxation, meditation, calming self-talk, spending time in nature, and exercise like yoga or tai chi.