Cortisol Optimization: Not Too High, Not Too Low

The wellness internet has declared cortisol the enemy. Every influencer is selling you a cortisol-lowering supplement, a "cortisol-conscious" workout, or a morning routine designed to "protect your cortisol." There's just one problem: you need cortisol. Quite a lot of it, actually.

The goal isn't low cortisol. The goal is the right cortisol at the right time.

What Cortisol Actually Does

Cortisol is a glucocorticoid hormone produced by your adrenal glands. It's essential for survival:

• Mobilizes energy — promotes gluconeogenesis (glucose from protein), glycogenolysis (glucose from glycogen), and lipolysis (fatty acids from fat stores)
• Regulates inflammation — cortisol is your body's primary endogenous anti-inflammatory. Without it, your immune system would destroy your own tissues
• Maintains blood pressure — permissive effect on catecholamine signaling
• Supports cognitive function — moderate cortisol enhances memory consolidation and executive function
• Drives the wake signal — the cortisol awakening response (CAR) is what gets you alert and functional in the morning

People with Addison's disease (insufficient cortisol) experience profound fatigue, muscle weakness, cognitive impairment, hypotension, and can die from adrenal crisis. Low cortisol is not a health goal.

The Diurnal Cortisol Curve

Healthy cortisol follows a predictable daily pattern:

• Cortisol awakening response (CAR): Cortisol spikes 50-60% within 30-45 minutes of waking. This is your body's natural alarm clock. It should be robust.
• Morning peak: Highest cortisol of the day, usually 6-9 AM. This drives morning alertness and energy.
• Gradual decline: Cortisol drops throughout the day — slowly and steadily.
• Evening nadir: Lowest cortisol in late evening, facilitating melatonin release and sleep onset.

The problem isn't high or low cortisol — it's a disrupted curve:

• Flat curve (no morning spike, elevated evening) → chronic stress pattern
• Inverted curve (low morning, high evening) → insomnia, weight gain, poor recovery
• Excessive amplitude (massive spikes) → anxiety, muscle catabolism, immune suppression
• Blunted CAR → morning grogginess, "adrenal fatigue" symptoms

"Adrenal Fatigue" — The Myth With Real Symptoms

"Adrenal fatigue" is not a recognized medical diagnosis. The Endocrine Society explicitly states it doesn't exist as a medical condition. Your adrenals don't "fatigue" from overuse.

But the symptoms people attribute to adrenal fatigue are real: chronic tiredness, difficulty waking, afternoon crashes, brain fog, salt cravings, reliance on caffeine. These typically reflect a dysregulated cortisol rhythm — the curve is wrong, not the total output.

What actually causes this:

• Chronic psychological stress (work, relationships, financial)


• Sleep deprivation or irregular sleep schedule


• Overtraining without adequate recovery


• Chronic inflammation (gut issues, autoimmune, infections)


• Blood sugar dysregulation


• Circadian rhythm disruption (screens, irregular schedule, shift work)

The fix isn't "supporting your adrenals" with supplements. It's restoring the cortisol rhythm.

How to Test Cortisol Properly

Single morning cortisol (serum): Nearly useless for optimization. It tells you one point on a curve. Lab ranges are absurdly wide (6-23 mcg/dL). You can have a completely disrupted rhythm and still fall within "normal."

DUTCH test (Dried Urine Test for Comprehensive Hormones): Measures cortisol metabolites across the day. Shows the curve, not just a single point. Also reveals free cortisol vs metabolized cortisol (important for understanding true cortisol activity vs clearance rate).

4-point salivary cortisol: Measures free cortisol at waking, noon, evening, and bedtime. Good for assessing the diurnal curve. More accessible and cheaper than DUTCH.

CGM + cortisol correlation: Wearing a continuous glucose monitor while tracking cortisol reveals how your stress response affects blood sugar. Not standard practice but increasingly useful for optimization.

Optimizing the Curve

Morning: Amplify the CAR

Goal: Robust cortisol spike within 30 minutes of waking.

• Sunlight exposure within 10 minutes of waking — photoreceptor signaling to SCN (suprachiasmatic nucleus) reinforces the CAR. This is Andrew Huberman's most evidence-based recommendation.
• Cold exposure (cold shower, 30-60 seconds) — acute cortisol spike that reinforces the morning peak and trains stress resilience
• Movement — even a brief walk amplifies the CAR
• Delay caffeine 60-90 minutes — controversial but logical: caffeine blocks adenosine, which can interfere with the natural cortisol clearance process. Let cortisol do its job first.

Afternoon: Controlled Decline

Goal: Steady decline without crashes.

• Blood sugar stability — avoid high-glycemic meals that spike and crash glucose (and cortisol)
• Protein + fat-forward meals — more stable energy, lower cortisol demand
• Brief stress exposure if needed — afternoon workout, cold exposure. Acute stress followed by recovery is healthy; chronic unresolved stress is not.

Evening: Facilitate the Nadir

Goal: Low cortisol by 9-10 PM to support melatonin and sleep.

• Dim lighting after sunset — blue light suppresses melatonin and can sustain cortisol
• No intense exercise within 3 hours of bed — training spikes cortisol, which takes 1-3 hours to normalize
• Relaxation practices — meditation, breathwork, gentle stretching. The evidence for these lowering evening cortisol is actually decent.
• Magnesium glycinate (400mg) — supports GABA activity and muscle relaxation
• Ashwagandha (300-600mg) — consistently reduces evening cortisol in clinical trials

Supplements for Cortisol Optimization

For excessive cortisol (chronically elevated):

• Ashwagandha (KSM-66, 600mg/day) — 14-28% cortisol reduction in RCTs


• Phosphatidylserine (300-800mg/day) — reduces exercise-induced cortisol spikes


• L-theanine (200-400mg) — modulates cortisol response to acute stress


• Omega-3s (2-4g/day) — anti-inflammatory, modest cortisol modulation

For blunted cortisol (flat curve, no morning spike):

• Rhodiola rosea (200-400mg, morning) — supports healthy stress response and energy


• Licorice root (low dose, morning only) — inhibits 11β-HSD2, the enzyme that deactivates cortisol. Use with caution: can raise blood pressure. Not for long-term use.


• B vitamins (especially B5, pantothenic acid) — cofactors in adrenal steroid synthesis


• Vitamin C (1-2g/day) — adrenals contain the highest vitamin C concentration of any organ

For both: Fix sleep, exercise, and blood sugar first. Supplements are the polish, not the foundation.

Training and Cortisol

Exercise is a hormetic stressor — it elevates cortisol acutely, which drives adaptation. The problem is volume and recovery:

Healthy: 45-75 minute resistance training sessions, 3-4x/week, with adequate sleep and nutrition → acute cortisol spikes followed by recovery → adaptation.

Unhealthy: 90+ minute daily sessions, insufficient sleep, caloric deficit → chronic cortisol elevation → muscle catabolism, immune suppression, overtraining syndrome.

Signs of exercise-induced cortisol dysfunction:

• Performance plateau or decline despite training hard


• Increased resting heart rate


• Sleep disruption (especially early-morning waking)


• Frequent illness


• Mood changes (irritability, apathy)


• Increased body fat despite training (particularly visceral fat)

The fix: deload week, increased calories, improved sleep. Not more training.

The Bottom Line

Cortisol is not your enemy. A dysregulated cortisol curve is. The goal is a strong morning spike, smooth decline through the day, and a clean trough at night.

Morning sunlight, consistent sleep timing, appropriate exercise, and blood sugar stability do 80% of the work. Ashwagandha and magnesium handle most of the remaining 20%.

Stop trying to lower cortisol. Start trying to optimize the curve.