How to Defeat Jet Lag, Shift Work & Sleeplessness

Andrew Huberman explains the science of circadian rhythms and practical tools to manage disruptions like jet lag, shift work, and irregular sleep in various life stages. Drawing from peer-reviewed studies, he emphasizes the internal ~24-hour clock tied to body temperature, light exposure, and behaviors that shift it reliably.

Core Circadian Mechanism: Know Your Temperature Minimum

Every cell follows a roughly 24-hour rhythm synced to light-dark cycles via the suprachiasmatic nucleus above the roof of the mouth. Body temperature dips to its lowest (temperature minimum) 90-120 minutes before typical wake time—average your last 3-5 wake-ups to find it, ignoring snoozes. Temperature then rises through morning (alertness increases) and peaks mid-afternoon before falling toward sleep.

Light sets this clock: sum ~100,000 lux (via eyes, not skin) before 9-10am using sunlight (even cloudy days provide 7-10k lux) or bright artificial lights to anchor wakefulness. Evening sunset light reduces retinal sensitivity, buffering late-night exposures. Avoid bright lights (1-1.5k lux shifts clock) 10-11pm to 4am or 4-6 hours before temperature minimum, as they delay the clock (later sleep/wake). Midday (post-9am to ~6 hours before minimum) is a "dead zone"—light there doesn't shift it.