Dr. Axe Ranks Seven Cortisol-Lowering Strategies With Evidence Scores
In a September 21, 2026 episode of The Dr. Josh Axe Show, Dr. Axe ranks seven ways to reset a flattened daily cortisol curve, giving consistent sleep a 10-out-of-10 evidence score and citing a study in which one poor night of 4 hours of sleep raised cortisol 37% the next day.
Axe cites a study of nearly 29,000 adults in which those under heavy stress who believed stress was harming their health had a 43% higher risk of dying early. He cites a University of Chicago study where morning light near 5,000 lux raised cortisol roughly 50% versus dim light. In a study of 264 adults with low magnesium, 300 milligrams daily for 8 weeks cut stress scores about 44%, with severely stressed adults dropping from roughly 60% to 12% by week 8. He also cites an ashwagandha study showing a 28% cortisol drop versus 8% in controls, a finding that one night of 4 hours of sleep raised cortisol 37% the next day, a screen-exposure study where evening screens cut melatonin 50 to 55% and delayed the sleep clock 1.5 hours, and a gratitude study showing a 23% cortisol drop after one month.
Cortisol isn't a villain, it's a rhythm. And almost nobody has been taught how to reset it.— Dr. Josh Axe
Axe explains cortisol as produced by the adrenal glands under direction from the hypothalamus-pituitary-adrenal axis, the brain-hormone system that sets the daily stress-hormone rhythm. Cortisol normally peaks about 45 minutes after waking and bottoms out near midnight; chronic stress, sleep debt and sugar can flatten that curve, leaving levels low in the morning and high at night. He attributes magnesium's effect to blocking NMDA receptors and supporting GABA, the nervous system's calming neurotransmitter, and credits slow breathing with stimulating the vagus nerve, the pathway that shifts the body out of fight-or-flight.
The episode names no journals, authors or publication years for the studies described, so the sample details, comparison groups and effect sizes cannot be checked beyond what Axe reports on air.
Dr. Axe's Take
Sleep is the lever I'd pull first. A single night of four hours drives cortisol up 37% the next day, and that kind of spike compounds if it keeps happening. I tell people to protect a consistent wake time and a wind-down window before bed rather than reaching for a supplement first. Once sleep and morning light are dialed in, I add two minutes of slow exhale-focused breathing or gargling to calm the vagus nerve. For added support, I've recommended ashwagandha at 300 to 600 milligrams daily, split into two doses, on top of those foundational habits.
— Dr. Axe