1 of 8

LESSON 3 · Sleep Like Your Life Depends On It

Why Sleep Won't Come

Falling asleep isn't a decision. It's a handoff your body makes only when three signals line up. Your core temperature has to fall. Melatonin has to rise in the dark. And your fight-or-flight system has to power down.

There's a second reason sleep stalls, and it has nothing to do with chemistry. It's a habit your brain built without asking you.