Overview
This lecture by Dr. Andrew Huberman provides a comprehensive guide to understanding, controlling, and optimizing cortisol rhythms to prevent or overcome burnout, improve well-being, and enhance daily performance.
Cortisol: Functions and Myths
- Cortisol is not just a stress hormone; its main function is to mobilize and direct energy, especially to the brain.
- It is produced by the adrenal glands in response to instructions from the brain via the HPA (hypothalamic-pituitary-adrenal) axis.
- Cortisol enables glucose release into the bloodstream for mental and physical activity.
The 24-Hour Cortisol Rhythm
- Healthy cortisol rhythm: high shortly after waking, steadily declines throughout the day, lowest at night.
- The "cortisol awakening response" (CAR) is a sharp increase upon waking, necessary for alertness.
- Four phases: minimal secretion before/just after sleep, slow rise mid-sleep, rapid rise pre-waking, peak after waking, then gradual decline.
Regulating Cortisol: Mechanisms and Tools
- The HPA axis and the brainâs SCN (suprachiasmatic nucleus, circadian clock) regulate the rhythm and response to stress.
- Negative feedback prevents cortisol from staying too high/low.
How to Increase Morning Cortisol (Energy, Focus)
- View bright sunlight within 30-60 minutes of waking (or 10,000 lux lamp if sunlight unavailable).
- Hydrate soon after waking (water/electrolytes).
- Caffeine prolongs morning cortisol effectiveness; delay intake 60-90 min after waking to prevent afternoon crash.
- Exercise in the same morning window each day strengthens the morning cortisol peak.
- Occasional deliberate cold exposure (max 1-2/week) can transiently raise cortisol.
- Eating grapefruit or black licorice in the morning can extend cortisolâs effects (grapefruit inhibits breakdown; licorice prolongs cortisol).
How to Lower Evening/Night Cortisol (Relaxation, Sleep)
- Dim indoor lights, avoid bright/blue (short wavelength) light after sunset.
- Avoid caffeine after ~2 pm.
- Use exhale-emphasized breathing or physiological sighs to lower stress and cortisol rapidly in real time.
- Include starchy carbs in the evening meal to help lower cortisol and promote comfort/sleep.
- Evening exercise: finish early, calm down with breathwork, starchy carbs, and dim light post-workout.
- Supplements: Ashwagandha (300-600mg) and apigenin (from chamomile tea, ~50mg) can lower evening cortisol, but only after behavioral tools.
Burnout: Types and Corrections
- Early-phase: stressed in AM, exhausted PMâuse NSDR/yoga nidra on waking, delay caffeine, get sunlight/hydration, flatten the morning peak.
- Late-phase: sluggish in AM, wired at nightâfocus on low evening light, calming routines, breathwork, starchy carbs at dinner, avoid late caffeine/stress.
- Both patterns require consistent daily routines to re-anchor cortisol rhythms.
Key Terms & Definitions
- Cortisol â Hormone that mobilizes energy, produced by adrenal glands.
- HPA Axis â Hypothalamic-pituitary-adrenal axis; main regulator of cortisol release.
- SCN (Suprachiasmatic Nucleus) â Circadian clock that governs cortisol's 24-hour rhythm.
- Cortisol Awakening Response (CAR) â Natural sharp rise in cortisol after waking.
- NSDR (Non-Sleep Deep Rest) â Practices (like yoga nidra) that reduce stress and cortisol.
- Negative Feedback Loop â Mechanism where high cortisol suppresses its further production.
Action Items / Next Steps
- Aim for sunlight exposure within 1 hour of waking daily.
- Hydrate and, if using, time caffeine 60-90 min after waking.
- Exercise regularly in consistent morning windows.
- Dim lights and avoid screens after sunset; use red/amber lights as alternatives.
- Try exhale-focused breathing techniques in the evenings.
- Use NSDR/yoga nidra if waking up stressed or as a relaxation tool.
- For persistent issues, adjust routines or consider supplements as described.