Cortisol is one of the body’s most misunderstood hormones. While it plays a crucial role in many biological processes, it’s often narrowly labeled as the “stress hormone”—an outdated survival mechanism that doesn’t fit modern life, something we’re told to lower through meditation, ice baths, or red-light therapy.
Fitness trainers warn against long runs to avoid “cortisol belly,” while influencers blame “cortisol face” on workplace stress. And now, social media has introduced the “cortisol cocktail”—a mix of coconut water, orange juice, salt, and lemon that TikTokers claim reduces stress and aids weight loss.
But how much of this is actually backed by science? And could obsessing over cortisol levels do more harm than good?
First, let’s clarify what cortisol really does—and yes, that includes managing our stress response. In fight-or-flight situations, it provides quick energy while temporarily suppressing non-essential functions like digestion and repair (we’ll discuss whether that’s harmful later).
“Cortisol is vital for regulating blood sugar by prompting the liver to produce glucose, ensuring steady energy for the brain and body,” explains Hannah Alderson, a nutritionist and hormone specialist. “It also helps control inflammation, keeping immune responses balanced, and plays a key role in metabolizing fats, proteins, and carbs.” Additionally, it regulates blood pressure, stabilizes mood, and supports recovery from illness.
But one of its most overlooked functions?
“It’s the hormone that wakes us up,” says Angela Clow, a psychophysiology professor at the University of Westminster. “Every morning, we experience a cortisol surge—the ‘cortisol awakening response’—which isn’t stress-related but helps sharpen focus. Ever wake up before your alarm when you have an early flight? That’s cortisol preparing your brain for the day.”
Recent research confirms that cortisol levels start rising about three hours before we wake, debunking the idea that waking itself is stressful. Instead, this natural increase helps transition the body from rest to activity—a key function of cortisol.
“A huge number of genes in your body respond to cortisol,” says Stafford Lightman, a professor at Bristol Medical School. “Its daily rhythm regulates genes in your brain, liver, and immune system.”
Throughout the day, cortisol levels gradually decline, with small bursts every 90 minutes to maintain bodily functions. This fluctuation makes measuring cortisol tricky—two tests taken 30 minutes apart could show vastly different results. In labs, researchers typically measure cortisol through blood or saliva samples.To understand how volunteers’ cortisol levels change in response to stress, researchers measure them multiple times daily. At-home tests aren’t as helpful—testing just once or twice a day might only reveal extreme highs or lows, missing the full picture.
What about the idea that everyday stresses keep our cortisol levels dangerously high? Some argue that our bodies, evolved to handle immediate physical threats like predator attacks, struggle to distinguish those from modern psychological stressors—arguments, work emails, or daily frustrations. The theory suggests these social stresses are particularly harmful because they’re constant, especially for those prone to overthinking, leaving little time for the body to recover.
In baboon societies, where hierarchy is strict, lower-ranking males suffer from weaker immunity and shorter lifespans because their stress responses are constantly activated. But baboons face real survival threats—exile from the group or failure to mate—unlike most human stressors, which are often more psychological. Some speculate that our bodies still react to minor social slights as if they were life-or-death situations, but is that really the case?
Probably not. Researchers have tested short-term stress responses using methods like cold-water immersion, timed problem-solving, or the Trier Social Stress Test (where participants give a speech and do math in front of a stern panel). Surprisingly, the effects aren’t as dramatic as you might think.
“Stressing humans is actually hard,” says Lightman. “Even ice-cold water barely affects cortisol. A major life event like a crucial job interview might spike stress, but it’s subjective—some people enjoy public speaking. With tests like Trier, the effect often disappears once people understand what’s happening.”
This means minor annoyances—a tense Zoom call or supermarket argument—likely don’t trigger cortisol spikes. Even if your body perceives them as threats, other hormones (like adrenaline) react first.
“It’s not just cortisol,” explains Dr. Thomas Upton. “Adrenaline and noradrenaline drive the immediate fight-or-flight response—the heart-racing, dry-mouth reaction to sudden scares. Cortisol only kicks in if the stress is prolonged.”
Chronic stress is where cortisol becomes a real concern—when the body rarely gets a chance to reset. But day-to-day frustrations? They’re unlikely to keep your levels dangerously high.Short-term stress likely isn’t harmful. But does prolonged stress—like ongoing family worries or mortgage concerns—or pushing yourself too hard with intense workouts make elevated cortisol more problematic?
“That’s more complicated,” says Professor Clow. “A brief stressful moment triggers a quick cortisol spike, which is fine—your body quickly returns to normal. But chronic stress, with repeated spikes, can disrupt your natural cortisol rhythm, regulated by your biological clock. Instead of a healthy daily cortisol pattern, you might experience ‘flat-lining,’ where cortisol fails to regulate other bodily processes properly.”
So, constant stress likely harms cognitive function and health. However, cortisol probably won’t change your appearance unless there’s a serious underlying issue. “Conditions like Cushing’s syndrome—where cortisol is extremely high, often due to an adrenal tumor—can cause weight gain around the stomach or a round, puffy face,” explains Niamh Martin, an endocrinology professor at Imperial College London. “But that’s only with very high cortisol levels.”
Even strenuous exercise, like a marathon, temporarily raises cortisol—but that doesn’t mean you should avoid pushing your limits. “A marathon is hugely stressful for the body,” says Upton. “You need that cortisol response. Without it, performance would suffer—you might even face serious risks.”
As for “cortisol detox” trends? Ignore the hype. Unless you have a medical condition, daily cortisol fluctuations aren’t worth stressing over. Some companies are developing continuous cortisol monitors, but for most people, these could cause unnecessary anxiety. “Glucose monitors, for example, create ‘worried well’ individuals who panic over normal post-meal spikes,” says Lightman. “Unless you’re an elite athlete, constant monitoring isn’t helpful—normal ranges vary widely.”
But if cortisol isn’t solely to blame, why does stress correlate with poor health, weakened immunity, and weight gain? “It’s complicated,” says Martin. “Stress might lead to emotional eating, less exercise, or poor sleep, which then disrupts cortisol—not necessarily the other way around. We still don’t fully understand how modern chronic stress affects our bodies long-term.”
So what does this mean for you?Is cortisol the culprit behind your health issues? “The most evidence-based approach is to see cortisol as more of a bystander rather than the cause of your problems,” explains Martin. “While chronic stress should be addressed for overall health, it’s not about artificially lowering cortisol levels—it’s a more holistic issue. Focus on self-care rather than expensive supplements or so-called ‘cortisol cocktails.'”
Here are five simple, free ways to combat chronic inflammation.
Clow shares some effective strategies for regulating cortisol: “Research shows that waking up early—within reason—helps maintain a healthy cortisol rhythm. Getting enough sleep and rising relatively early appears beneficial. There’s also growing evidence that nighttime light exposure disrupts melatonin production, which can lead to higher cortisol levels during sleep.” That said, prioritizing consistent, sufficient sleep may be even more important.
Exercise helps regulate cortisol, but intense workouts aren’t always necessary. “Gentle activities like walking, stretching, or Pilates can be more effective than an intense HIIT session on an empty stomach,” says Alderson. “Breathwork is incredibly powerful and can be done anywhere. Small moments of joy—like laughter, a hug, or a nature walk—are easier to incorporate than grand gestures like week-long retreats. Even if they don’t directly impact cortisol, they matter more than people realize.”
Ultimately, remember that cortisol is on your side. While modern life might occasionally throw your hormones off balance, your body’s stress response is generally beneficial. Aim for daily movement, regular sleep, and balanced eating—and don’t stress over the rest. You really don’t need the extra worry.
