Circadian Rhythm: Your Body’s Original Schedule

Why timing is more powerful than we think.

We talk about sleep like it’s an event. Something that happens at the end of the day. Something to “get better at". Something we can just “fix".

But sleep is a cycle, not a switch. And it doesn’t begin at bedtime. It begins with light.

Because your body runs on rhythm. A built-in, 24-hour loop that shapes everything from your hormones to your hunger, your focus, your mood, and even your immune response.

This loop is known as your circadian rhythm, and it’s not just about night and day. It’s about when your body expects to do what, and how well it can do it when the signal is clear.

This rhythm is biological, not optional. It’s already in you, whether you’re listening or not.

Your body doesn’t just sleep and wake. It orchestrates.

Every organ, every system, every hormone pulse and digestive signal follows an internal rhythm, timed with precision, shaped by cues you may not even realise you’re giving.

Cortisol rises in the morning, meant to bring you into the day with energy and clarity. Insulin works best when the sun is high and the body expects food. Melatonin, your nighttime hormone, waits in the wings until the lights dim and the world quiets.

Even your gut microbes have circadian patterns, showing up and doing their jobs at specific times, depending on when and how you eat.

This isn’t a wellness trend. This is how your biology communicates.

But most of us are out of step

And not because we’re doing anything wrong. Just because modern life runs on a very different schedule than our bodies do.

We stay inside during daylight. We stare at bright screens at night. We eat irregularly, sometimes not at all, then suddenly too much. We drink caffeine when we’re tired and push harder when we should rest. We sleep at odd hours and wake up with alarms that jar us into motion before we’re ready.

We override. We adapt. We cope.

And eventually, the rhythm gets distorted.

You might still be functioning. But you’re foggy. Unfocused. Wired at night, tired in the morning. You can’t fall asleep when you want to, or stay asleep once you do. You wake up groggy. You feel hungry at all the wrong times. Your skin, hormones, and digestion start to reflect something’s off, even if your tests say “normal".

Because your body isn’t broken. It’s offbeat.

Circadian disruption doesn’t just affect sleep

That’s often where people notice it, but it goes far deeper than that. It affects:

• Blood sugar regulation

• Thyroid hormone conversion

• Estrogen and progesterone rhythm

• Immune signalling

• Cognitive function and memory

• Mitochondrial repair

• Inflammation

• Cravings and emotional resilience

You might be doing everything “right”, eating well, exercising, taking supplements, but if your timing is off, the impact is diluted.

Because your body does certain things best at certain times. And when it gets the wrong cues, or no cues at all, it has to guess.

So what throws off the rhythm?

Not getting morning light is one of the biggest. Your body uses sunlight, real, bright, outdoor light, as its main circadian anchor. Without it, melatonin stays elevated too long in the morning, cortisol doesn’t peak properly, and your energy, digestion, and mood never fully arrive for the day.

On the flip side, too much light at night (especially overhead LEDs and screens) tells your brain: It’s still daytime. Melatonin production stalls. Sleep feels light, disrupted, or delayed. The next day starts foggy. And the loop continues.

Irregular or late-night eating also disrupts the rhythm. Your digestion follows a circadian pattern too. When you eat at midnight, your gut isn’t ready to break things down, and inflammation, reflux, and insulin resistance can follow.

And let’s not forget stress. A dysregulated nervous system can override circadian rhythm altogether.

When you live in constant go-mode, your cortisol curve flattens. You don’t get the rise in the morning, or the drop at night.

Everything stays elevated. You’re not alert. You’re on edge. You’re not tired. You’re shut down.

Rhythm is the medicine

This doesn’t mean you need to overhaul your life or keep a military schedule. It just means choosing a few reliable cues and repeating them often.

Because your body responds best to patterns it can count on.

Start in the morning. Open the blinds. Step outside. Let light hit your face. Don’t rush to caffeine. Eat something warm with protein. Give your system the signal: the day has begun.

During the day, eat at consistent times, enough to keep your blood sugar stable and your nervous system calm. Move in natural ways. Breathe. Pause.

In the evening, dim the lights. Turn off bright screens early. Lower the stimulation.

Let your system land. Choose a signal that says: we’re done now. It doesn’t have to be dramatic. It just has to be repeated. A cup of tea. A lamp you always switch off last. A journal line, even if you don’t finish the page.

Rhythm isn’t restrictive. It’s regulating. And when your body starts trusting the pattern, everything gets easier.

What starts to shift?

At first, it’s subtle.

You begin to wake with a little more clarity, before the alarm startles you. Even if the night wasn’t perfect, your body feels more willing to meet the morning. There’s less fog, less resistance. The day begins not with a jolt, but with a gradual return.

You start to get hungry at the right times. Not from stress, or boredom, or a blood sugar crash, but from rhythm. Your digestion feels more predictable. Food lands better. Meals satisfy, not spike. You find yourself reaching for what feels grounding, not just convenient.

By evening, you feel a sleepiness that isn’t shutdown—it’s permission. A gentle sense of done. You no longer feel wired at 10pm and resentful at 7am. You notice when your system wants to rest, and for once, you listen.

Your blood sugar stops swinging. Your energy steadies. Your nervous system gets a little quieter, not flat, just less reactive. Your baseline isn’t as fragile. And your hormones? They begin to fall back into pattern, not because you forced them, but because the conditions for balance were finally restored.

You don’t have to micromanage everything. You just needed to send the right signal.

And your body knew what to do with it.

A rhythm older than us

There’s a theory, one I love, that circadian rhythm began with ancient microbes.

Long before humans. Before mammals. Before even plants.

Billions of years ago, single-celled organisms were floating in the ocean, adapting to the rising and setting sun. They learned to shield themselves from UV rays during the day, and repair DNA at night. Over time, they developed internal clocks, not to keep time, but to stay in relationship with the environment.

That rhythm got passed on. Preserved. Refined. Baked into mitochondria. Carried forward through evolution. We inherited it.

So when your body rises with light and rests with dark, when you eat by day and restore by night, you’re not just being disciplined. You’re tapping into a biological memory. A rhythm that’s been with us since before we had names for things.

You don’t have to understand every hormone to feel this. You just have to notice what your body remembers when you stop overriding it.

Because this rhythm isn’t something we created. It’s something we forgot.

The bottom line

You don’t need to perfect your routine. You don’t need to go to bed at 9pm every night or time your meals like a spreadsheet.

You just need to bring back rhythm.

Step outside in the morning light. Eat when your body expects food, not when your schedule leaves space for it. Let the day end with softness. Let sleep be something you fall into, not fight for.

Start with a single cue. The same lamp dimmed at the same time. The same breath before breakfast. The same walk into daylight, even if it’s short.

And trust that rhythm is not about restriction. It’s about restoring a pattern your biology has been waiting for.

Because when you remember the rhythm, your body remembers how to respond. And healing doesn’t feel like a project anymore.

It feels like coming home.

Want to see where the science comes from? For the extra curious, the references are here.