The guide · Updated 2026
The cortisol guide
Cortisol is your body's primary stress hormone — produced by the adrenal glands and following a daily rhythm that affects sleep, weight, mood, energy, and immunity. This is everything that matters about it, organized by what you actually need to know.
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Symptoms of high cortisol
Cortisol face, cortisol belly, sleep issues, weight gain, hair loss — what's clinically real and what's TikTok.
- · Cortisol face
- · See all symptoms
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How to lower cortisol
Sleep, breathing, exercise, foods, supplements — ranked by evidence and effect size. Not generic wellness copy.
- · Sleep — the biggest lever
- · Supplements ranked
- · Foods that lower cortisol
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Cortisol levels reference
Normal ranges by time of day, age, and gender. What a healthy diurnal curve looks like — and what disrupts it.
- · Diurnal cortisol curve
- · Morning cortisol quiz
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Testing your cortisol
At-home saliva, blood, urine, and wearable estimation — what each test measures and when to use each.
- · Test methods compared
- · Free cortisol quiz
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Free cortisol tools
Cortisol — most asked questions
What is cortisol? +
Cortisol is your body's primary stress hormone, produced by the adrenal glands. It follows a daily (diurnal) rhythm — peaking 30–45 minutes after you wake, declining through the day, and reaching its low point around midnight. Cortisol regulates blood sugar, blood pressure, immune response, inflammation, and sleep-wake cycles. Chronic elevation or disruption of the rhythm is linked to sleep problems, weight gain, anxiety, and metabolic issues.
What are the symptoms of high cortisol? +
Common signs include difficulty falling asleep despite exhaustion, waking between 3–5 AM, weight gain concentrated around the midsection, sugar and salt cravings, "wired but tired" energy, facial puffiness (popularly called "cortisol face"), brain fog, and weakened immunity. See our full guide to symptoms of high cortisol.
How do you lower cortisol naturally? +
The highest-leverage interventions in order: fix sleep (consistent timing + 7+ hours), reduce alcohol, get morning sunlight, practice daily paced breathing, do zone 2 cardio 3x/week, and supplement magnesium glycinate. Ashwagandha is the supplement with the strongest direct cortisol-lowering evidence.
Can wearables measure cortisol? +
No consumer wearable directly measures cortisol — it requires blood, saliva, or urine testing. Wearables like Apple Watch can estimate cortisol patterns using validated biometric correlates: heart rate variability (HRV), sleep stages, resting heart rate trend, and recovery balance. Cortisol+ combines these signals into a continuous cortisol-pattern estimate.
What time of day is cortisol highest? +
Cortisol peaks 30–45 minutes after waking — this is called the Cortisol Awakening Response (CAR). Levels decline through the day, reach their low point around midnight, and start rising again 3–4 hours before wake. Disruption of this diurnal rhythm is associated with shift work, jet lag, chronic stress, depression, and HPA axis dysregulation.