Your core body temperature needs to drop by about 1–2°F for you to fall asleep. Your body doesn't care what you want. It needs the temperature drop to signal "time to shut down." A cold shower 60–90 minutes before bed triggers rapid vasodilation after you get out, which dumps heat from your core through your skin and accelerates this natural temperature drop.
You fall asleep faster. You spend more time in deep sleep — the phase that actually repairs your body. And you wake up feeling like you actually slept.
This isn't some biohacker bullshit. The link between body temperature and sleep onset is textbook physiology. The cold shower is just the cheapest way to use it — unless you want to drop $3,000 on a cooling mattress.
I stumbled onto this by accident. It was summer 2019, our AC was broken for a week, and I was taking cold showers before bed just to stop sweating. By day three I noticed I was falling asleep in under 10 minutes — normally I'd toss and turn for 30–45. Gaya thought I was losing it when I kept taking cold showers after the AC was fixed.
Six years later, I haven't stopped. I've probably missed fewer than 20 nights. It's the single highest-ROI sleep intervention I've ever tried — 2 minutes of being cold for 7+ hours of actually sleeping. The hardest part is the first 5 seconds. After that, your body adapts and you actually start to like it. I know that sounds insane. Just try it for a week.
We didn't read about this stuff in a book.
We lived it, broke ourselves, fixed ourselves,
and wrote down what actually worked.