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What Sympathetic Nervous System arousal means for officer safety

Corrupted sensory data, slowed cognition, and automatic, uncontrollable physical reactions that characterize SNS arousal have big implications for those involved in law enforcement or self-defense training

Not long ago I was walking my little 10-pound Terrier a block away from home when we heard an explosive “pop” from behind us.

After an initial wince and flinch away from the sound, my head involuntarily whipped around to face the source. My body spun with it, squaring off in the same direction. I stood with bent knees, a forward distribution of weight and chin tucked. My left hand clenched down hard on the leash, while my right simply curled up into a fist. My hands moved up above belt level and my arms floated out from my side, bent at the elbow and cocked to leap into action.

I was ready to fight.

My dog — who is probably far smarter than me — was sensibly committed to the alternative (flight) and was desperately trying her best to pull my arm out of its socket.

It took a moment to figure out that the sound was not a gunshot, but a leftover aerial firework from Independence Day that some neighbor had just shot off.

Modern-Day Caveman
I had just experienced a classic Sympathetic Nervous System (SNS) arousal. My brain detected a sudden, unanticipated threat and sounded the “all hands on deck” signal, which sent a powerful mix of chemicals into my system. Blood flow was redirected through vasoconstriction, priming the major muscle groups for immediate response and peak strength — all while simultaneously diminishing my fine motor skills.

My blood pressure and respiratory rate spiked as my heart and lungs raced in preparation for the anticipated exertion. My brain commanded my body to square up against the expected avenue of attack in an aggressive fighting posture that also protected my areas of vulnerability.

It did all of this without any conscious thought or action. The orders necessary to put this dormant plan into action were issued by the subconscious and dispatched along neural pathways that have been part of our makeup for millennia. In fact, if a prehistoric man had been walking alongside me, it’s likely our responses would have been identical.

Fast, Strong, Deaf and Dumb
My SNS arousal may have improved the speed and strength of my physical response to the threat, but my sensory system and cognitive processing were both negatively affected in those first fractions of a second.

Because the biological reflex is to focus on the central core of vision, I experienced a reduction in peripheral vision, and it took a while to see the sparks from the firework overhead. Similarly, while my ears strained to detect vital clues (someone yelling or a firearm action being cycled, for instance), all I could hear clearly was the distinctly unhelpful sound of my dog’s nails clawing at the concrete — a form of auditory exclusion that is a disturbing (yet common) component of SNS arousal.

My cognitive capabilities took an immediate hit too. A “thinking man” would have quickly rationalized that standing out in the open was not a good choice if the mystery sound was indeed hostile gunfire, but there I stood, feet planted, while my brain struggled to assimilate all the clues, locate the “threat” and determine what was happening.

I gave no thought to accessing my concealed firearm, because my mind was busy trying to move my body into the aggressive, empty-hand fighting stance that the primitive, biological playbook called for. By the time my startled, rational brain kicked in and considered movement to cover or drawing the firearm — probably no more than a second after the sound — I was already figuring out that it was unnecessary.

Training Implications
Corrupted sensory data, slowed cognition, and automatic, uncontrollable physical reactions that characterize SNS arousal have big implications for those involved in law enforcement or self-defense training. Consider just these three:

1.) Are we teaching skills that will hold up under stress? For instance, will bladed shooting stances work when your body naturally squares itself to the threat? Are we teaching shooting or defensive tactics skills that rely on fine motor coordination, which may suffer during SNS arousal?
2.) Are we teaching skills that account for the uncontrollable physical reactions our people are likely to experience? Do we teach the draw with hands starting from a high, defensive “flinch” position or unrealistically hovering near the gun? Since we’re likely to clamp down on a flashlight or ticket book that’s already held in the support hand (instead of dropping it) when attacked, should we be emphasizing more one-handed shooting in training?
3.) Do our students get to experience the effects of SNS arousal during training? Do we safely expose our students to realistic scenarios that offer the chance to experience the stress and confusion of a real fight, or the deleterious effects of SNS arousal on dexterity, coordination and fine motor skills? It’s important for them to experience these things in a controlled environment (and train accordingly) before they experience them for real in the street.

Hopefully, my recent experience will prompt you to think about how and what you are training. Will it work when your inner caveman comes out to play?

Mike Wood is the son of a 30-year California Highway Patrolman and the author of “Newhall Shooting: A Tactical Analysis,” the highly-acclaimed study of the 1970 California Highway Patrol gunfight in Newhall, California. Mike is an Honor Graduate of the United States Air Force Academy, a graduate of the US Army Airborne School, and a retired US Air Force Lieutenant Colonel with over 26 years of service. He’s a National Rifle Association (NRA) Law Enforcement Division-certified firearms instructor, senior editor at, and has been a featured guest on the Excellence In Training Academy and American Warrior Society podcasts, as well as several radio and television programs. He’s grateful for the opportunity to serve and learn from the men and women of law enforcement.