Yes, the fight or flight response can be controlled. The fight or flight response occurs when you are exposed to something you fear. Fearful situations include: hearing footsteps behind you when walking home in the dark; giving a speech to an audience; making new friends at a party; interviewing for a new job; taking a test; flying; being trapped in a dark closet; hearing gun shots; natural disasters. There are numerous other situations that make you fearful, and these fearful situations trigger the fight or flight response.
The fight or flight response is responsible for the physical effects of fear and anxiety. Fear activates the amygdala, an almond-shaped part of the brain which controls emotions. The activated amygdala in turn activates the Sympathetic Nervous System and the HPA axis (hypothalamic pituitary adrenal axis). The Sympathetic Nervous System then activates a neural response which activates smooth muscles and activates the adrenal medulla (part of the adrenal glands on top of the kidneys) to release adrenaline and noradrenaline (stress hormones), and the HPA axis is activated and triggers the release of cortisol (stress hormone) from the adrenal cortex (part of the adrenal glands). The end result is the fight or flight response induces the following physical effects of fear and anxiety: increased heart rate, chest palpitations, increased rate of breathing, shortness of breath, numbness and tingling in the arms and legs, butterflies in the stomach, lump in the throat, and dry mouth.
The fight or flight response is adaptive when dealing with real dangers in the environment…it can help you to survive dangerous situations by preparing you to fight the danger or to flee from it. However, when anxiety triggers the fight or flight response on a chronic basis, then the physical effects can lead to physical and mental exhaustion, as you are constantly on alert and on guard for any possible danger in the environment. But for anxiety, this fight or flight response is not adaptive, as the danger is more in your head than a reality in the environment.
So the best way to control the fight or flight response is to develop coping skills to address the anxiety, such as changing the way you think about a situation (less negative thinking), addressing your avoidant behaviors which maintain the anxiety, getting adequate rest and sleep, getting enough exercise to defuse your nervous energy, and engaging in meditative and relaxation techniques to reduce your overall anxiety levels. Natural supplements can also be considered to further help you to reduce your anxiety levels.