If you’ve scrolled through TikTok lately, you may have come across a few videos that claim cortisol, a.k.a the “stress hormone,” is behind every annoying issue you can think of: fatigue, bloating, hair loss, blurry vision, bruising, eye twitching, dizziness, bad sleep, probably even getting ghosted by your crush.
While there may be a grain of truth in some of these (well, except for the ghosting), the bigger picture is a bit more nuanced, Allison K. Rodgers, MD, an endocrinologist and ob-gyn at the Fertility Centers of Illinois, tells SELF. “Cortisol is a really important hormone,” she says. “It’s responsible for regulating a lot of things in your body, including your metabolism and energy stores.”
But what happens when levels of that hormone get thrown out of whack? Here’s how cortisol works and how to tell if it’s actually impacting your health.
What is cortisol—and how does it affect my body?
Though cortisol can affect nearly every part of your body, its primary function is really pretty simple: to get you out of bed and ready for the day. “Cortisol is produced from your adrenal glands, which are positioned on top of your kidneys,” Nebojsa Nick Knezevic, MD, PhD, a clinical professor of anesthesiology and surgery at the University of Illinois at Chicago, tells SELF. The hypothalamus in your brain, which regulates your circadian rhythm, a.k.a. your internal clock, controls its release. So as you wake up, your adrenal glands pump out cortisol, which boosts your heart rate and gets you moving, Dr. Knezevic explains.
Your cortisol levels peak anywhere between 6 a.m. and 8 a.m. (though that really varies from person to person and depends on what your typical sleep-wake schedule looks like) and then taper off throughout the day. Eventually, cortisol reaches its lowest point at night—just in time for you to wind down for bed. The next morning, the cycle starts all over again, per Dr. Knezevic. Basically, cortisol has an essential role and your body has a finely tuned system to make sure you produce enough of it.
Of course, that natural pattern only applies to your bland, uneventful days, says Dr. Rodgers. “Cortisol is our body’s fight-or-flight hormone,” she explains. “In evolutionary history, when our ancestors turned the corner and saw a lion, they’d have two choices: run away or fight it.” Both of those scenarios cause your heart rate, blood pressure, and blood sugar levels to soar, which helps you better use your brain and muscles to survive. A sudden burst of cortisol makes that happen and also tamps down non-essential bodily functions, like digestion, while you get the job (whatever it is) done.
Problem is, your brain isn’t the best judge of what’s an actual threat, Dr. Rodgers explains: “Say you’re walking down the street and you run into your ex-boyfriend unexpectedly…You’re probably going to have a rise in cortisol.” However, she notes, once that person gets a few blocks away (and assuming they don’t hit you up with a ‘Hey stranger ;)’ text later that day), that spike should come back down.