Expert shares the surprising role cortisol plays in our sleep — and why it's just as important as melatonin

A man who is unable to sleep at night covers his head with a white pillow while holding a white alarm clock in the other hand.

You’ve likely heard of cortisol as “the stress hormone,” the one that spikes when your boss drops a big project in your inbox or when you’re running late and stuck in traffic.

But cortisol is more than just your internal “let’s get out of here” system; it’s also a key player in how your body regulates sleep.