The science of when, with the doses spelled out.
Protocol cards, primary-source citations, and dose-accurate reviews, for morning light, sleep architecture, chronotype, and every other lever that resets a circadian clock.
Is Insomnia Genetic? What Twin Studies and Genome Research Actually Show
Eating Before Bed and Sleep: What a Late Meal Does to Your Night
The Best Time to Exercise for Sleep: Why Evening Workouts Are Mostly Fine
Browse by category
Five hubs covering the chronobiology levers that reset a circadian clock, light, sleep, chronotype, tools, edge cases.
Light & Zeitgebers
Morning sunlight, lux dose, blue light, red light, dawn simulators, with the research.
Sleep Architecture
Stages, cycles, sleep debt, napping protocols, why you wake at 3am.
Chronotype & Personalization
Not everyone has the same circadian phase. Protocols that assume 7am wake time fail for late chronotypes.
Interventions & Tools
Light therapy lamps, sleep masks, sunrise alarms, blue-blockers, trackers, all dose-tested.
Edge Cases
Jet lag, shift work, parenthood, perimenopause, ADHD, where generic advice fails.
Featured stacks
The most-read protocols this month, each with its own Stack Score and reviewer.
Is Insomnia Genetic? What Twin Studies and Genome Research Actually Show
Insomnia does run in families, and large genetic studies have found real inherited risk, but genes set a vulnerability rather than a destiny. What twin studies and genome-wide research show about the heritability of insomnia, why the environment and habits still decide whether that vulnerability becomes a lasting problem, and why the treatment is the same either way.
Eating Before Bed and Sleep: What a Late Meal Does to Your Night
A late meal is not automatically bad for sleep, but eating large, heavy, or the wrong foods close to bedtime reliably disturbs it, and meal timing is also a signal to your body clock. What the research says about reflux, blood sugar, and circadian meal timing, and how to eat in the evening without wrecking your night.
The Best Time to Exercise for Sleep: Why Evening Workouts Are Mostly Fine
Regular exercise is one of the most reliable ways to sleep better, and the old warning to avoid evening workouts has largely not held up. What the research says about how exercise improves sleep, whether the time of day matters, and the one narrow exception, vigorous exercise finished right before bed, that can genuinely delay sleep onset.
Cortisol and Sleep: The Morning Hormone That Times Your Wake
Cortisol is not only a stress hormone; it follows a strong daily rhythm that peaks in the early morning to drive waking and falls to its low at night to allow sleep. What the research says about the cortisol awakening response, how stress and disrupted sleep push the rhythm out of shape, and why fixing the rhythm matters more than chasing a single cortisol number.
What Happens When Your Circadian Rhythm Is Disrupted
Your body clock does far more than control sleep; it schedules hormones, metabolism, temperature, and alertness across the day. When behavior falls out of step with the clock, through shift work, jet lag, social jet lag, or erratic light, the misalignment shows up as poor sleep, daytime dysfunction, and, over the long run, metabolic and mood consequences. What the research says, and how the clock realigns.
How to Improve REM Sleep: What Actually Raises It and What Just Wrecks It
You cannot force REM sleep directly, but several everyday habits quietly suppress it, and removing them is how you get more. What the research says about when REM happens across the night, why alcohol and short sleep cut it most, and why the single biggest lever is simply giving yourself enough time asleep in the early morning hours.
Every protocol on the site. Sorted by last reviewed. Stack Score is a 0–100 confidence number, methodology link in the footer.
What changed in the index this week. Every protocol move is logged because secrecy is for advertorials.
- [2026-04-26 09:14]INDEXEDmorning-sunlight-protocol v2.1 (Zeitzer dose-response added)
- [2026-04-25 17:42]REVIEWEDbest-light-therapy-lamps-2026, clinical reviewer signoff
- [2026-04-24 11:08]REFRESHEDwhy-you-wake-at-3am, Bonnet 2003 sleep-fragmentation refresh
- [2026-04-23 08:31]DRAFTEDjet-lag-protocol-east-vs-west, eastbound section drafted
- [2026-04-22 14:55]QUEUEDperimenopause-sleep-shift, added to queue, brief due 2026-05-03
- [2026-04-21 19:03]FLAGGEDmelatonin-3mg-vs-0.3mg, re-flagged, Brzezinski meta-analysis re-read
- [2026-04-21 09:12]INDEXEDwhat-a-zeitgeber-is, primer published
Updated when posts move stages. The pipeline page is the long form.
Public methodology, versioned like software. Read what we score on, what we won't, and what the tiers actually mean.
Cited at the trial. Doses measured at usable distances. Never paid by lamp brands or supplement vendors.
Educational content. Not a sleep clinic. Suspected sleep disorders go to a board-certified sleep physician.