Many people start T3 medication hoping for more energy and mental clarity—only to end up feeling wired, anxious, or unable to sleep. In this episode of Thyroid Shorts, Dr. Eric Balcavage explains why too much or too little T3 can both amplify anxiety and insomnia, and how to restore calm by shifting from defense mode to recovery mode. You'll learn how the brain's fear center (the amygdala) interprets stress, how local T3 activity inside the brain differs from global thyroid output, and why "state before hormone" is the key to lasting recovery. Featuring insights from two pivotal papers: Psychoneuroendocrinology (2024): Evidence for thyroid hormone regulation of amygdala-dependent fear relevant memory and plasticity PLoS ONE (2011): Adult-Onset Hypothyroidism Enhances Fear Memory and Up-regulates Mineralocorticoid and Glucocorticoid Receptors in the Amygdala Timestamps: 00:00 – Intro – Is T3 causing your anxiety and insomnia? 02:00 – Input → Interpretation → Response: how the brain reads threat 05:00 – The amygdala as the body's alarm system 08:00 – The Threat Perception Loop and defense physiology 11:00 – Local vs global thyroid adaptation: T3 in the amygdala 13:00 – The T3 Paradox: too little vs too much T3 17:00 – Shifting from defense to recovery mode 19:00 – Key takeaways & how to calm the system before adjusting hormone Key Takeaway: Your thyroid follows your brain's perception of safety. Calming the nervous system restores efficient T3 conversion—without overstimulation.