Cortisol and Stress
Cortisol, commonly known as hydrocortisone, is the major hormone secreted by the adrenal glands when the body is under stress. Cortisol is critical when the body is under attack—whether the attackers are predators, invaders like viruses, bacteria, or allergens, or perceived attacks like stressful jobs, difficult relationships, or toxic environments. Whether you’re coming down with the flu, frustrated in a traffic jam, or in tears over a break-up, your body’s biochemical response is the same: cortisol mobilizes glucose so you can run fast and think quickly. It increases epinephrine (adrenaline) and norepinephrine output so your heart can beat faster, increasing the blood flow to your muscles, brain, and heart. It regulates your immune system.
Robert Sapolsky’s book “Why Zebras Don’t Get Ulcers ” helps us understand the stress response. When a lion chases a zebra, the zebra’s cortisols shoot up so he can run fast and think quickly to escape the lion. And if the zebra survives the chase, he returns to eating grass, while his cortisols return to stable levels (until the next lion comes along). But in our modern lives, our cortisol output is chronically elevated—we’re not literally being chased, but our body responds as if the lions are at our heels.