Cortisol is the body’s main stress hormone, and our adrenal glands naturally release it throughout the day. Just about every organ in the body has receptors that react to cortisol, explains Ian Leber, M.D., the chief medical officer of Sollis Health.
“Cortisol is essential for living. It peaks at the beginning of the day to support getting out of bed and decreases throughout the day to allow ‘sleep pressure’ to build. Without cortisol, we would lack the motivation to get up and do things,” says Shera Raisen, M.D., a physician at concierge primary care center The Lanby.
“Cortisol increases glucose in the bloodstream, enhances your brain’s use of glucose, and it also increases the availability of substances that repair tissues,” explains dual board-certified doctor Seema Bonney, M.D. This makes us feel more awake, alert, and ready to take action. So it makes sense that any time we’re faced with a perceived threat, the adrenals churn out some more cortisol to help all the organs in our body prepare to fight or flee the situation.
The issue is that as cortisol revs our bodies up, it diverts energy away from the processes that aren’t essential for the fight-or-flight response, such as digestion and rest.
“Typically, perceived threats pass quickly and the hormone levels return to normal resulting in a return to baseline for those nonessential systems,” Bonney explains. However, “when stressors are consistently present and you constantly feel under attack, this fight-or-flight response stays turned on.” This is when cortisol can start to negatively affect things like sleep quality, blood sugar balance, immunity, and digestion.