Hi there, it's Matt here and welcome back to the podcast. I want to tell you about a woman I met

who came to me and my clinical team for sleep help. Let's call her Jessica. Her story is

illuminating in a very literal way. She was 38, worked in marketing from a one-bedroom apartment, and was, by any

reasonable measure, doing everything right. All the sleep hygiene tips, all sorts of supplements

that in truth were a waste of money. She would buy every new gadget that promised better sleep.

She had downloaded the apps. She had read the

articles. She had quietly eliminated evening caffeine with a discipline that was deeply impressive.

She had optimized everything she knew to optimize. And she was exhausted, not dramatically, not in a way anyone else

would notice, but in the way of someone whose nights never quite fully recovered the days. What

Jessica didn't know was that two specific moments in her ordinary day were shaping her sleep

more than all of that combined. The first

happened about 40 minutes after her alarm sounded when she sat down at a north-facing desk

in a room whose blackout curtains she never opened. The second happened around 6 o'clock

when she switched on the bright overhead light

in her living room and opened her laptop. Two moments, two biological signals, but here's the thing.

From her brain's internal clock's point of view, both of them were completely wrong. This episode is about why her brain registered that

and the problems it caused and the solution we found for her. It turns out that your body runs on a

clock, not a metaphor, an actual molecular timepiece that your cells inherited from ancestors

who lived before artificial light existed,

before alarm clocks, before scheduled meetings. Every cell in your body carries its own

cycling clock genes, and those cellular clocks govern nearly everything. When cortisol peaks in the morning, when your

body temperature drops towards sleep, when your immune system shifts gears, when you feel sharp,

...