Zeitgebers (Time Cues)

The Primary Zeitgeber

The single most powerful, most actionable circadian intervention. Get morning light.

ZeitgeberLight therapy FDA-cleared (SAD)

When You Eat vs What You Eat

The same meal eaten at night is metabolically worse than eaten in the morning.

MetabolismDietary timing science

Food as a Peripheral-Clock Zeitgeber

Food is the master zeitgeber for your organs, strong enough to override light.

ZeitgeberDietary timing science

The Evidence-Based Morning Routine

Consistent wake time, morning light, then everything else. The highest-yield routine there is.

OptimizationBehavioral protocol

Seasonal Affective Disorder (SAD) · Circadian Mood Disruption

Recurrent winter-pattern depression tied to a delayed circadian clock, not the same thing as the winter blues.

Circadian-Linked Mood DisorderNo drug approved specifically for SAD; light boxes are unregulated wellness devices, not FDA-cleared for SAD. Bupropion XL is FDA-approved for SAD prevention.

Body Temperature Rhythm as a Zeitgeber

You fall asleep as your core cools. Warm your feet, cool your core, sleep faster.

ZeitgeberFoundational biology

Evening Light Exposure & Devices

The wavelength gets the blame, but brightness, and what you do on the screen, matter more.

DisruptionConsumer products vary

eTRE · Circadian-Aligned Eating Window

The most metabolically powerful eating pattern, and the hardest to fit a social life around.

MetabolismDietary timing strategy

Movement as a Circadian Zeitgeber

Morning exercise shifts you earlier; evening shifts you later. Performance peaks late afternoon.

ZeitgeberBehavioral science

Schedules, Meals & Social Rhythm

Regular social rhythms anchor the clock, and stabilizing them treats mood disorders.

ZeitgeberBehavioral science