Fight or Flee: Understanding Your Response to Stress

Jul 24, 2019 9:30:00 AM / by Active Threat Solutions by Defense in Depth

Will you know what to do if an active shooter steps foot in your office or educational building? Your body will react before you have the time to process the situation sufficiently. There are two survival-induced reactions for all mammals, humans and animals, in response to high-stress and threatening situations - fight or flight. According to the New York Times, there have been 163 shootings in the past 50 years with 25 public mass shootings where four or more victims were killed. Many of the deadliest shootings have occurred within the past few years, as active shooting events are increasing. 

Are you ready to take action? Continue reading to understand your body’s response to stressful situations and how you can stay safe during life-threatening events.


An active shooter event can be defined as one or more persons, with unclear motives, involved in killing or attempting to kill multiple unrelated individuals in a public area. According to The Alert Center at Texas State University, over the last decade, active shooters can be found targeting locations such as businesses (40 percent), schools (29 percent), outdoors (19 percent), and other (12 percent). 

How your body responds to threat:

The “fight or flight” response is your body’s survival mechanism towards enabling a quick reaction to hostile situations through a release and production of stress hormones. The production of hormones like adrenocorticotropic, corticosteroid and cortisol cause psychological and physiological effects. 

Let’s first understand the psychological reaction when confronted with a stressful, life-threatening situation. 


The stress response begins in your brain. Your eyes and ears send the perceived information to the amygdala (distress signal that interprets images and sound, contributes to emotional processing). When danger is recognized, distress signals are sent to the hypothalamus which communicates to the rest of the body there is enough energy to fight or flee through the autonomic nervous system (ANS)

The ANS has two components:

  • Sympathetic Nervous System - provides the fight or flight response to develop a burst of energy
  • Parasympathetic Nervous System - calms the body down after danger passes and promotes what’s called a “rest and digest” response

After the hypothalamus sends signals to the ANS, the ANS triggers the adrenal glands. Adrenal glands pump adrenaline into your bloodstream, causing physiological changes. The nutrients pouring into the bloodstream give your body the energy needed to respond. 

As these changes happen quickly, the amygdala and hypothalamus pick up on the situation before the brain’s visual center can process it. This reason is why you’ll find your body reacting first before you’ve been able to comprehend a situation completely.

To find out more about the physiological process of the stress response, review the Harvard Medical School’s Harvard Health Publishing article about “Understanding the stress response.”


As a recap, when the stressor activates the hypothalamus, it stimulates the pituitary gland which secretes hormones (adrenaline, noradrenaline, cortisol). 

Physical reactions your body has during a high-stress event may include:

  • Release of blood sugar (glucose) and fats for energy
  • Rapid heartbeat
  • Increased breathing due to lung dilation 
  • Increased blood pressure
  • Extra oxygen sent to the brain, increasing alertness and sharper senses
  • Tense muscles
  • Perspiration  
  • Decrease in digestive activity 

When the threat passes, cortisol levels fall, causing energy to be produced. 

Lasting effects of chronic stress 

Chronically activated stress can contribute to long-term mental health problems like depression, anxiety and post-traumatic stress disorder (PTSD). These conditions inhibit the ability to deal with normal stress and cause you to be stuck in a permanent fight or flight stage. 

Additional long-term effects include:

  • Repeated stress activation responses take a negative toll on the body
  • High-blood pressure
  • Clogged arteries 
  • Obesity, directly (people eating more) and indirectly (decreasing sleep and exercise)


The body judges stressful situations through sensory input, processing and stored memories. The fight or flight response was discovered by Walter Cannon in 1915. The built-up energy your body produces when faced with stressors can protect humans from attackers, help them escape and ensure the body is mobilized.  

Houston PD: Run, Hide or Fight 

The Houston PD developed an informative video to inform the general public how to safely and appropriately respond when faced with an active shooter event. The following options you can act on are listed from highly recommended to least likely to suggest for those in the situation. Please note that your number one priority is getting out of harm's way

fight or flee

  • Run: The best option available for your safety
  1. If possible, develop a plan to evacuate and escape
  2. Encourage others to leave with you, but don't let anyone slow you down if they are indecisive
  3. You are important, not your belongings
  4. Help others escape 
  5. Prevent others from walking into the danger zone
  6. Call 911 immediately when you are safe
  • Hide: If you are unable to make an escape plan and get out safely, find a hiding place
  1. Act quickly to turn off lights and lock doors
  2. Silence your cell phone
  3. Ideally, find a safe room or closet then hide behind large, protective objects
  4. Try your best to remain calm and quiet
  5. Be out of the shooter’s view
  6. Do not trap yourself or restrict options for movement 
  • Fight: This option should be a last resort, but if confronted with the active shooter follow the suggestions below
  1. Incapacitate the shooter
  2. Act with aggression and commit to your actions
  3. Improvise with your weapon of choice
  • How To Respond When Authorities Arrive: 
  1. Follow their instruction, calmly 
  2. Keep your hands visible at all times
  3. Avoid pointing and yelling
  4. For those who are injured, know that help is on its way

Overall suggestions from Houston involves being aware of your surrounding environment and knowing that shooting events are unpredictable as victims are chosen randomly. Remain as calm as possible and take the appropriate steps to stay safe. 


At Active Threat Solutions, we have trained more than 6,000 employees and 50 organizations. Our Active Threat Training seminar educates and empowers all individuals to be knowledgeable when confronted with threats, including an active shooter. We utilize simple solutions to solve the complex problems for people of all ages, occupations and experience levels. 

We provide additional services in risk management, emergency response, post-incident communications for businesses, active threat responses for security professionals and more. Our team of current and former law enforcement officers, federal agents, military and Department of Defense instructors can equip you with the skills and knowledge necessary for the maintenance of a safe environment. Stay up-to-date on the latest training tips and news stories by visiting our Learning Center

Know what to do. Take your first step in creating a safe work environment and get trained by our experts today. 



Topics: active threat training, fight or flight

Active Threat Solutions by Defense in Depth

Written by Active Threat Solutions by Defense in Depth

Active Threat Solutions by Defense in Depth was developed to equip individuals with the knowledge and confidence they need that will inspire them to implement crisis solutions in the workplace making them feel safer and more empowered.