How to Control Your Cortisol & Overcome Burnout

KEYPOINTS

• 01

  Cortisol's main job is to mobilize energy, not just to respond to stress

  Cortisol is a steroid hormone made from cholesterol, like testosterone and estrogen. Its central role is deploying blood glucose so the brain and body have energy for whatever the day demands, including stressors, exercise and focused work. Huberman argues that understanding its 24-hour rhythm, rather than treating it as 'the stress hormone,' is what tells you which tool to use at which time.

• 02

  Cortisol follows four predictable daily phases

  A classic study of cortisol secretion found a six-hour low period running from about 4 hours before lights-out to 2 hours after. Cortisol then rises slightly in hours 3 to 5 of sleep and climbs fast in hours 6 to 8, which overlaps with the REM-rich part of the night. A fourth phase follows waking. If you sleep only six hours, you miss most of that late-night rise, and seven hours captures only part of it.

• 03

  The first hour or so after waking is a unique window to boost cortisol

  Alongside the HPA axis, the suprachiasmatic nucleus (SCN) can drive extra cortisol through a parallel pathway via the splanchnic nerve. That window is open for roughly 1 to 3 hours after waking. The SCN receives input from melanopsin retinal ganglion cells, which respond to big shifts from dim to bright light, so morning light is the main way to open this pathway.

• 04

  A bigger morning peak leads to lower evening cortisol

  Because cortisol regulates itself through negative feedback, a high early peak triggers a steady decline starting around late morning. That leaves you energetic into the afternoon and low in cortisol by night, which helps you fall and stay asleep. Huberman calls this the point to 'bold underline.' Chronically high cortisol at the wrong times is linked to immune suppression, abdominal fat and the rounded 'moon face.'

• 05

  Caffeine barely raises cortisol in habitual users but prolongs it

  In people who have had caffeine daily for about five days, 100–300 mg doesn't raise cortisol much. Non-habitual users see a substantial rise. Caffeine does extend how long cortisol stays effective, which is why Huberman suggests delaying it by 60 to 90 minutes if you crash in the afternoon. That way the morning cortisol curve comes down gradually rather than falling off a cliff. If you want caffeine right away, that's fine, as long as you still get light, water and movement.

• 06

  Exercising at a consistent time anchors the cortisol rhythm

  Exercise is a strong entrainment cue. If you train within the same 2–3 hour window, ideally four to six days a week with at least one full rest day, your body learns to release cortisol in anticipation, and you start to feel more energetic in the hour before your usual session. Huberman describes this as a Pavlovian effect on a longer timescale.

• 07

  Cold exposure raises cortisol only when it's occasional

  Deliberate cold exposure raises cortisol only if you do it about once or twice a week. Done more often, the cortisol effect fades, but the rise in dopamine, norepinephrine and epinephrine continues and, as far as is known, does not saturate. Huberman says there's no evidence that regular cold exposure chronically raises cortisol in women more than in men.

• 08

  Evening light is a potent cortisol trigger because baseline cortisol is low at night

  Because evening cortisol is so low, the hypothalamus is primed to respond, and even moderate short-wavelength light can push cortisol up and suppress melatonin. Huberman recommends dimming lights, using red bulbs or a red phone filter (triple-click accessibility shortcut), or glasses that block short-wavelength light. Late-day sunlight in spring and summer is fine.

• 09

  Starchy carbohydrates at dinner help keep evening cortisol low

  Higher blood glucose reduces the drive to release cortisol, which helps explain why carb-heavy comfort foods feel calming. Huberman eats moderately or low carb through the day and includes rice, potatoes or yams at dinner around 7–7:30 pm. Ideally you'd stop eating about two hours before bed, but he allows a small snack if hunger keeps you awake.

• 10

  Low-carb diets raise cortisol only temporarily

  In the studies Huberman reviews, cortisol rises during the first three weeks of a low-carb diet and then settles back down. His test is simple: if you're low carb and sleeping well, don't worry. If you're sleeping poorly, try adding starch to your last meal. Insulin resistance (metabolic syndrome) is the exception, because cortisol stays high when cells can't use the glucose.