Cortisol
Cortisol is your body's primary stress hormone, produced by the adrenal glands. It regulates the stress response, blood sugar, inflammation, immune function, and the sleep-wake cycle. Cortisol follows a natural daily rhythm — peaking 30–45 minutes after waking (cortisol awakening response) and declining through the day to near zero at night. Chronic disruption of this rhythm underlies many modern health problems.
Normal range
How Vsense measures it
Vsense derives a cortisol estimate from physiological stress indicators — HRV, heart rate patterns, breathing, and autonomic nervous system markers. For clinical-grade cortisol measurement, a morning blood test, saliva test, or 24-hour urine collection is recommended.
How it's scored
Normal morning cortisol: 10–20 μg/dL. Chronically elevated cortisol disrupts nearly every body system. Chronically low cortisol (as in adrenal insufficiency) also causes significant dysfunction.
What a high reading means
Chronically high cortisol causes: weight gain (especially belly fat), poor sleep, weakened immunity, blood sugar dysregulation, reduced libido, anxiety, depression, and accelerated aging. Cushing's syndrome (very high cortisol from tumour or long-term steroid use) is a medical condition. More commonly, chronic psychological stress and poor sleep are the culprits.
What a low reading means
Low cortisol can cause: extreme fatigue, salt cravings, low blood pressure, and difficulty recovering from illness. Adrenal insufficiency (Addison's disease) is rare but serious — requires medical evaluation. 'Adrenal fatigue' as typically used online is a disputed concept — genuine adrenal insufficiency is diagnosed by blood testing.
How to improve it
Exercise
- Moderate exercise lowers cortisol — but overtraining (too intense, too long, too often) actually spikes it
- Yoga and tai chi are particularly effective at reducing cortisol over time
- Walking in green spaces (nature) has the strongest cortisol-reducing effect of any exercise
- Aim for enjoyable exercise — dreaded exercise sessions raise cortisol, not lower it
Diet
- Reduce caffeine — it directly stimulates cortisol release, especially on an empty stomach
- Eat regular meals — blood sugar crashes spike cortisol as the body tries to raise glucose
- Phosphatidylserine (found in egg yolks, organ meats, soy lecithin) directly lowers cortisol in studies
- Dark chocolate (70%+) in moderation reduces cortisol response to stress
- Vitamin C (500–1,000mg) reduces post-exercise cortisol and overall cortisol levels
Lifestyle
- Sleep optimisation is the most powerful cortisol regulator — cortisol spikes when sleep is poor or shortened
- Mindfulness meditation reduces cortisol levels within 8 weeks of regular practice
- Social support and meaningful relationships lower baseline cortisol
- Limit alcohol, recreational drugs, and excessive work hours
- Set clear work boundaries — chronic overwork keeps cortisol chronically elevated
Natural remedies
- Ashwagandha (KSM-66 extract, 300–600mg daily) reduces cortisol by 20–30% in multiple clinical trials
- Rhodiola rosea helps regulate the stress response and prevents cortisol spikes from acute stress
- Phosphatidylserine supplements (400–800mg/day) reduce exercise-induced and stress-induced cortisol
- Magnesium (glycinate or threonate, 300–400mg before bed) reduces cortisol and improves sleep
Frequently asked questions
What does cortisol do to my body?
Cortisol has widespread effects: it raises blood sugar (to fuel the stress response), suppresses digestion, suppresses the immune system, raises blood pressure, and increases alertness. Short-term, these are helpful. Chronically, they cause metabolic damage.
Why is cortisol highest in the morning?
The cortisol awakening response (CAR) — a 50–100% spike in cortisol within 30–45 minutes of waking — is a normal, healthy pattern. It prepares your body and brain for the day. People with chronic burnout often lose this morning peak, leading to fatigue.
Does cortisol make you gain weight?
Chronically elevated cortisol does cause weight gain — especially visceral (belly) fat. Cortisol promotes fat storage, increases appetite for sugary and fatty foods, and breaks down muscle. Stress eating combined with stress hormones is a potent weight-gain combination.
What is adrenal fatigue?
Adrenal fatigue is a popular but controversial concept suggesting the adrenal glands become 'tired' from chronic stress. Conventional medicine does not recognise it as a diagnosis. Genuine adrenal insufficiency (Addison's disease) is serious and diagnosed by blood testing. Many symptoms attributed to adrenal fatigue are better explained by chronic stress, poor sleep, thyroid issues, or depression.
Can cortisol affect my sleep?
Strongly. Cortisol and melatonin are on opposite cycles — when cortisol is high, melatonin is suppressed. If cortisol doesn't fall sufficiently in the evening (common with chronic stress), it directly prevents sleep onset and reduces sleep quality.
