10/22/2026
Your cortisol probably isn’t too high. It’s high at the wrong time.
Cortisol is supposed to peak shortly after you wake up and fall to its lowest point around bedtime. Light hitting your eyes is one of the biggest inputs that sets that daily curve. A flattened curve (low in the morning, elevated at night) is associated with poorer sleep, daytime fatigue, and worse cardiometabolic markers.
Four levers I go through with patients:
☀️ Morning light, in your eyes
Get outside within the first hour of waking. Skip the sunglasses, and don’t stare at the sun. Even overcast daylight is many times brighter than indoor lighting, and it’s the strongest timing signal your circadian clock gets.
🌇 Daylight again later in the day
Getting outside in the afternoon and evening adds to your total daylight exposure. People who get more bright light during the day appear to be less sensitive to light at night. The evidence supports daylight exposure overall, not anything unique about sunset.
🌙 Dim the lights after dark
Bright light at night suppresses melatonin and pushes your clock later. Overall brightness matters more than color. So dim the overhead lights, switch to lamps, and turn your screen brightness down. Night mode helps a little, but it doesn’t make a bright screen fine.
🫁 Box breathing during the day
Inhale 4, hold 4, exhale 4, hold 4. A few minutes of slow breathing reliably lowers your heart rate in the moment. Think of it as a stress-regulation tool. The data on long-term cortisol changes is limited.
If you rank these by evidence, light timing is the heavy hitter, and breathing is a useful tool on top of it.
If you’re doing all of this and still feel flat in the morning and wired at night, that’s worth measuring instead of guessing. A multi-point cortisol curve shows what your rhythm actually looks like.
Dr. Luke Sorrell, MD, FACP | Sorrell MD
Educational content, not medical advice.
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