Cortisol — The Stress Hormone That Hates Bedtime

Cortisol is one of your main stress hormones, released by the adrenal glands under the control of the HPA axis. In a healthy rhythm, cortisol peaks in the early morning — helping you wake up, raise blood sugar a little, and mobilise energy — then gradually slopes down through the day, reaching its lowest point at night so sleep can deepen.

When life is chronically loud — deadlines, worry, overwork, emotional storms — that curve can flatten and stay elevated into the evening. High night‑time cortisol tells your system, “We are not safe enough to power down.” Heart rate stays a bit higher, body temperature doesn’t drop properly, and you hover in lighter, more fragmented sleep or struggle to fall asleep at all.

Cortisol also tangles with other sleep‑related actors. It can blunt melatonin release, nudge blood sugar and insulin in ways that create 3 a.m. wake‑ups, and keep the mind in a scanning, threat‑seeking mode. That’s the “tired but wired” state: physically exhausted, mentally on patrol.

You can’t and shouldn’t try to “delete” cortisol — you’d be flat and unresponsive without it. The goal is rhythm, not zero: bright light and movement earlier in the day, wind‑down rituals and dimmer light at night, caffeine that bows out early, and stress‑taming habits (breathwork, therapy, boundaries) that teach your axis it’s allowed to lower the volume after dark.

Why It Matters

Understanding cortisol turns “I can’t sleep, my body is broken” into “my stress system thinks it’s still daytime” — a problem you can influence from several angles.

Closing Line

You don’t need to banish cortisol — you just need to convince it that midnight is not the time for a staff meeting.