Circadian Rhythms

Your body has an INTERNAL CLOCK — the CIRCADIAN RHYTHM — running on roughly a 24-hour cycle. It governs sleep timing, hormone release, body temperature, hunger, alertness, even cell division. The master clock is in your brain (suprachiasmatic nucleus or SCN). Local clocks exist in many organs. Together they coordinate when your body should be active vs resting. The 2017 Nobel Prize in Medicine went to scientists who decoded the molecular basis of circadian rhythms.

Setting the clock. The circadian clock isn't exactly 24 hours — it needs daily input to stay synchronized. The strongest cue: LIGHT (especially morning sunlight). Other cues: meal timing, exercise, social schedule. WITHOUT cues (people in caves), the body settles into a slightly longer than 24-hour cycle. Modern life often DISRUPTS circadian rhythms — bright screens at night, irregular schedules, jet lag, shift work. Disruption is linked to obesity, diabetes, depression, and even cancer.

Tips for healthy rhythms. (1) MORNING SUNLIGHT (15+ minutes) — anchors your clock. (2) CONSISTENT sleep/wake times. (3) AVOID screens 30-60 min before bed. (4) DARK bedroom at night. (5) EAT meals at regular times. (6) AVOID caffeine after early afternoon. (7) Exercise in MORNING or AFTERNOON (not late evening). Travelers can use timed light exposure to reset for new time zones.

Your circadian rhythm is one of the most powerful (and underutilized) levers for energy, mood, and health. Working with it pays daily dividends.