Welcome back to Protocols Study Group — my YouTube-exclusive series where I'm working through Andrew Huberman's book Protocols: An Operating Manual for the Human Body, one protocol at a time. This is essentially my version of fan art. I'm not affiliated with Huberman, his podcast, or Stanford — I'm simply a fan, reading the book, highlighting what sticks, and teaching it back to you because that's how it solidifies in my brain.
Put simply, we win by sleeping. Sleep is the foundation of mental and physical health and performance, and sleep deprivation is linked to many diseases and mental health issues. So before the new protocol, a quick recap of where we've been in Chapter 1, Protocols for Sleep:
- Protocol 1: view sunlight as soon as possible after waking — 5–10 minutes within 30–60 minutes of waking — to keep your body and brain on schedule.
- Protocol 2: view sunlight in the late afternoon, which also keeps you on schedule and protects your retinas from artificial light after dark.
- Protocol 3: avoid bright lights in the final hour before bedtime. LEDs emit a disproportionate amount of short-wavelength light that can reduce melatonin and activate the habenula, a brain part tied to depressive feelings and disappointment. The fix: dim lights, candlelight, red lights, or blue-green blocking glasses.
- Protocol 4: find your ideal sleep and wake times and stick to them, in sync with your chronotype. Sleep runs in ~90-minute cycles of non-REM (N1, N2, N3) and REM, and N3 deep sleep is where growth hormone releases and the brain washes out waste. About 7.5 hours is 5 cycles.
This episode is Sleep Protocol 5: lower your core body temperature at night.
The protocol: cool down to fall asleep
Ever notice how difficult it is to fall asleep when you're too warm? That's not a quirk — it's the mechanism. Your core body temperature falls through the day, reaches its minimum at night, and rises again before you wake. Lowering it is one of the triggers that starts non-REM sleep. The protocol is simple: help that drop along.
Room temperature: 65–68°F
The book's recommendation for the room you sleep in is 65–68°F. Cooler than most people keep a bedroom during the day, and deliberately so — a cool room makes the core-temperature drop easier instead of fighting it.
The hot shower trick
This one sounds backwards until you hear the mechanism: a hot shower before bed makes you drowsy, not because the heat itself puts you to sleep, but because of what happens after. Warming your hands and feet triggers a compensatory response — your body dumps heat from its core to the periphery, and your core temperature drops. The shower is the setup; the drop afterward is the point.
Hands and feet out from under the covers
Same principle, no shower required: keep your hands and feet outside the covers while you sleep, and skip the socks. Extremities are radiators. Letting them breathe releases heat and keeps the core-temperature drop going through the night.
The temperature minimum
Your core temperature isn't flat — it slides down all day toward a nighttime minimum, then climbs back up before waking. Sleep timing works best when it rides that curve instead of fighting it, which is why the earlier protocols (morning light, afternoon light, dim evenings, a consistent schedule) all feed into this one.
Why cooling helps sleep start
A lower core temperature helps initiate non-REM sleep, and melatonin releases in sync with the temperature drop. At the same time, the body shifts toward its parasympathetic state — calmer, slower heart rate, less movement — and blood flows out to the hands and feet. Cooling, melatonin, and calm all arrive together, and that combination is what opens the door to sleep.
The brain's thermostat: the preoptic area
The control center here is the preoptic area of the hypothalamus — the brain's thermostat. Warming the hands and feet signals it to trigger the compensatory cooling response that lowers core temperature. It's a small patch of brain doing an outsized job: it reads peripheral warmth and answers by cooling the core.
My own take: shower timing matters
I've always showered before bed, so that part wasn't a change for me. What I have noticed, a few protocols in, is that allowing a bit of time after the shower — instead of showering and going straight to bed — lets my core temperature actually drop. And on the nights I do get into bed right after a hot shower, sticking my feet out from under the covers helps get the drop going. The hardest nights to fall asleep, for me, are the nights I feel warmest. That tracks exactly with what the book describes.
The road ahead
There are 15 protocols for sleep in this book and we'll be covering them all here, then moving into other chapters such as protocols for stress, nutrition, focus, and more. As noted in the episode, the book was recently $28 for hardcover, $17 for Kindle, and $0.99 for the audiobook with membership — but it's not really meant to be read cover to cover. It's a manual to reference protocols as needed, so the hardcover, kept on the coffee table, picked up frequently, jumped around in, and highlighted, is the recommendation.
And if you want to put any of these protocols into practice: the Headphones to Action Workbook is available on the website, thisweekinmyheadphones.com — a 16-page PDF workbook, downloadable immediately after purchase, for $9. Reflect on what you heard, set an intention, and formulate a 7-day action plan — and it doesn't have to be a podcast; anything you hear counts.
Show notes
- Book: Protocols: An Operating Manual for the Human Body by Andrew Huberman
- Protocol: Sleep Protocol 5 — lower your core body temperature at night (room 65–68°F; warm shower before bed; hands and feet out from under the covers, no socks; temperature minimum at night)
- Key idea: cooling the core triggers non-REM sleep, in sync with melatonin and a parasympathetic shift; the preoptic area of the hypothalamus is the thermostat that runs the compensatory drop
- Kevin's takeaway: shower timing matters — give the drop time after a hot shower, and when in bed warm, feet out from under the covers helps; the hardest nights to fall asleep are the warmest ones
- Disclaimer: independent fan-made educational project. Not affiliated with, endorsed by, or sponsored by Andrew Huberman, Huberman Lab, or Stanford University. For educational purposes only — not a substitute for professional medical advice.