Now, you can think of
cortisol as the drummer of this rhythm…
Just like a drummer keeps time for a band, cortisol sets the pace for your Circadian rhythm…telling your body when it’s time to wake up, stay alert, and when to start winding down.
Cortisol is
supposed to peak in the morning to help you wake up…
Then slowly drop off as the day goes on.
By nighttime, cortisol should be at it lowest - so that melatonin can rise to help you fall asleep and stay asleep
But if you’re under chronic stress (consistently high cortisol)…
Or eating super late (food is a “wake” circadian signal)…
Or looking at a bright screen (blue light tricks your brain into thinking it’s still daytime)...
Or reading scary news before bed (activates fight-or-flight, which raises cortisol)…
(Some nights I was doing all the above!)
…your sleep rhythm gets all messed up.
Which means your cortisol might stay high. Or even SPIKE at night.
And high nighttime cortisol keeps melatonin from rising like it should…
Causing that
“wired but tired” feeling we all dread. Wanting to fall asleep but not being able to.
In fact, researchers have found that people with insomnia often have
elevated cortisol levels at night, a likely cause of their sleep issues.
So…What Can You Do?
As you can probably guess…
Keeping your
cortisol as low as possible before bed is going to be the best solution.
You need to give your brain very clear signals:
“Hey, it’s nighttime. No funny business. Time to start winding down for sleep…”
Try Following The 6 Circadian “Zeitgebers”:
(Zeitgebers = German for time-keepers)
These are known to have the biggest impact on your cortisol levels at night…
1 - Light
Bright light (particularly blue light) suppresses melatonin and signals the brain to be alert.
What to do: Get bright natural light in the morning (ideally within 30 minutes of waking) and dim lights 1–2 hours before bed. Avoid bright screens, or wear blue light-blocking glasses at night.
2- Food timing
Eating signals your body that it's time to digest and be alert, so eating late can keep cortisol elevated and delay melatonin.
What to do: Try to finish dinner 2–3 hours before bed. Avoid late-night snacks if you can.
3 - Mental/emotional stimulation
Scary news, intense movies, or even conflict with a spouse at night activate your sympathetic nervous system, driving up cortisol.
What to do: Safeguard your mental health after 8pm. For me, that means no news, no scrolling on X, and no reading work emails.
4 - Physical activity
Strenuous activity can increase cortisol and keep it high for several hours.
What to do: Light movement before bed is great (walking, yoga) but try to avoid intense workouts after 6pm.
5 - Consistency
When you constantly shift your bedtime or wake time, your brain doesn’t know when to release melatonin or drop cortisol.
What to do: Aim for a consistent sleep and wake time, even on weekends (within 1 hr).
6 - Body temperature
Your core body temperature should drop at night to initiate sleep.
What to do: Keep your bedroom cool (~65°F), and try a warm bath/shower 1–2 hours before bed to trigger a cooling response.
If this seems overwhelming and is a huge shift from your current routine, just try to tackle one at a time…
For example, if you’re used to scrolling Tik Tok right before bed – try replacing that with reading a book. Do that for a week or two, and then move on to the next improvement, like shifting your dinner up 1 hour.