The Primary Zeitgeber
The single most powerful, most actionable circadian intervention. Get morning light.
Circadian Health
Optimization
10 topics. 6 rest on strong human evidence. Ordered with the best evidenced first.
10 topics in Optimization
Adenosine · Sleep Pressure / Process S
The molecule that tracks how long you have been awake, and the one caffeine blocks to hide the bill.
CAR · The Morning Activation Surge
A programmed 50-100% cortisol surge after waking. Not stress, your clock turning the day on.
Acute Circadian Desynchrony
Eastward is harder than westward. The clock re-syncs about one hour per day.
The Hormone of Darkness
Not a sleeping pill, a darkness signal. And most people take 10x too much.
The Evidence-Based Morning Routine
Consistent wake time, morning light, then everything else. The highest-yield routine there is.
eTRE · Circadian-Aligned Eating Window
The most metabolically powerful eating pattern, and the hardest to fit a social life around.
Movement as a Circadian Zeitgeber
Morning exercise shifts you earlier; evening shifts you later. Performance peaks late afternoon.
Magnesium, Glycine, Theanine, Apigenin & More
Magnesium, glycine, and theanine have real (modest) data. Most sleep stacks oversell.
Sleep Trackers & Wearables · Measurement
These devices measure movement, heart rate, HRV and temperature. They infer sleep stages.