The Deepest Well: Healing the Long-Term Effects of Childhood Trauma and Adversity—A Transformative Guide to Understanding Childhood Trauma and Health

by Nadine Burke Harris

When you see the bear, your amygdala immediately sounds the alarm telling your brain to be afraid because bears are scary! Your brain then activates your SAM and HPA axes, triggering the fight-or-flight response. Signals from the SAM axis travel along nerves from the brain to the adrenal glands telling them to make adrenaline, which is responsible for many of the feelings that we associate with being terrified. Adrenaline causes the heart to beat stronger and faster, sending blood to all the places that need it. It causes your airways to open so that you can take in more oxygen. It raises your blood pressure and shunts blood toward your skeletal muscles (necessary for running and jumping) and away from that tiny muscle that holds your bladder closed, which is why scared people feel like they’re going to pee in their pants and sometimes do. It also converts fat to sugar for energy. The SAM axis also activates the noradrenergic nucleus of the locus coeruleus, which, as I like to say, is the scientific term for the part of the brain responsible for “I don’t know karate but I do know c-razy!” This is the within-the-brain stress-response center, and it gets you amped up. (Picture Oakland Raiders fans after a winning game or, worse, a losing game.) Adrenaline and noradrenaline are powerful stimulants, designed to help you think more clearly so that you can figure out the quickest path to safety. They also create feelings of euphoria, that adrenaline rush that makes you think you...