Circadian Rhythm — Your 24‑Hour Body Clock

Your circadian rhythm is a network of 24‑hour clocks in your brain and body that coordinate when you feel awake or sleepy, hungry or satisfied, alert or foggy. The master clock sits in the SCN (suprachiasmatic nucleus) and takes its main cue from light. Morning light nudges the clock earlier; late‑night light pushes it later. Around that, peripheral clocks in organs like the liver, gut, and muscles take hints from meals, movement, and sleep timing.

In a friendly schedule, these clocks line up: cortisol rises in the morning, melatonin climbs at night, digestion expects food at regular times, and body temperature dips gently before bed. When you constantly shift bedtimes, binge‑sleep on weekends, eat heavy meals at odd hours, or work rotating shifts, the clocks fall out of sync. That “social jet lag” can leave you sleepy at work, wired at bedtime, and weirdly hungry at 11 p.m.

Some people are natural night owls or larks — that’s partly genetic and partly age‑related. For extreme forms (like DSPS or ASPS), shifting the clock may need structured light exposure, melatonin timing, and behavioural tweaks guided by a clinician. For many others, small habits go a long way: consistent wake time, morning light, meals on a rough schedule, and a wind‑down that starts before you’re already shattered.

Your circadian system is not a productivity enemy; it’s the set designer for your energy. Fighting it is like arguing with time zones. Working with it feels less like discipline and more like surfing a wave that’s already there.

Why It Matters

Once you see your sleep as a timing issue, not a moral one, you can stop calling yourself lazy and start adjusting cues like light, food, and wake times instead.

Closing Line

Your body has a schedule even if your calendar doesn’t — honouring that rhythm is less self‑help and more good manners.