Peter wakes up 7:30am, does intermittent fasting for 16 hours, eats his first meal at 12pm, finishes dinner at 8pm, does a gym workout at 9:30pm, and gets in bed by 11:30pm. He eats healthy, gets some morning sunlight, and otherwise works in an office most of the day.
Tom wakes up with sunrise at 6:30am, eats breakfast shortly after, gets a morning workout in under the sun, and then goes to work. He steps out for an afternoon walk, finishes dinner by sunset, and is in bed by 10pm. He also eats healthy.
To the common person, both Peter and Tom are living healthy lives:
They each get ~8 hours of sleep.
They get a daily workout in.
They eat healthy.
What’s missing from the narrative is how their circadian clocks are completely different, and it’s affecting their health. Tom is living closer to circadian alignment - coordinating his activity timing with the sun and with each other, whereas Peter’s circadian clocks are not coordinated, resulting in disharmony and misalignment in his body.
Researchers experimentally induced circadian misalignment in healthy adults by shifting their sleep, eating, and activity schedules 12 hours out of sync with their internal clocks. In just 3 days, this increased blood pressure, reduced healthy nervous system control of the heart, and raised inflammatory markers.1
But this is not restricted to night shift. If we are in circadian misalignment regularly, it can lead to poor cardiovascular and inflammatory outcomes for us as well.
Circadian alignment is about creating harmony between our body’s clocks
Too often, the health debate is focused on which activities are good and bad for you. But the importance of activity timing gets missed from the debate. Our body runs on internal clocks that tell our cells when to perform different activities.
We have a master clock in the brain, called the suprachiasmatic nucleus (SCN).2 And then we have what are called “peripheral clocks” in different organs like the gut, liver, pancreas and so forth.
Our clocks can keep time on their own, but they rely on daily cues, namely light and food, to stay synchronized with the outside world and with each other. Other activities like exercise timing also impact the clock, but light and food timing are the largest signals.
The master clock, the SCN, is primarily set by light. This is why morning sunlight is key, it stimulates the SCN via light to the eyes, and tells it the day has begun. Food timing is one of the strongest timing signals for peripheral clocks, particularly in metabolic organs like the liver, gut and pancreas.
“Circadian alignment” is another term for synchrony between clocks. The idea that the various clocks in our body tell roughly the same time and tick harmoniously.
In Peter’s case, his SCN wakes up in the morning, but his peripheral clocks are not stimulated till his first meal at 12pm. He eats dinner after sunset, again disconnecting light cues with food timing cues. And exercises late at night, giving his peripheral clocks another stimulant when his SCN should be winding down. His clocks are not working in alignment with each other.
In Tom’s case, the SCN and peripheral clocks are closely aligned with each other and the sun. He stimulates his SCN through the sunrise cue and eats breakfast shortly after, keeping them in sync. He continues to get light cues throughout the day and aligns his dinner with sunset.
For ideal health, the SCN and the peripheral clocks need to stay in harmony with each other and with the sun. When they regularly fall out of sync, the body begins to behave like a discordant orchestra, disrupting processes like metabolism, immune function and cellular repair, and over time contributing to chronic disease.
The big question: Who cares if my clocks are not running in sync? Does it matter?
Circadian clocks are not just about sleep and melatonin. These clocks also regulate the timing of cell division, DNA repair, immune surveillance, metabolism, timing of hormones and more. Circadian misalignment doesn’t just mean, “a bad day of sleep”. Regular misalignment increases cardiovascular and cancer risk, raises blood pressure and inflammatory markers, and results in poor immune health, reduced DNA repair, and low glucose tolerance.
Lack of circadian alignment can lead to changes in repair processes and proper immune functioning. This can result in unabated proliferation or growth of tumors. A well-functioning immune system can stop the growth of tumors, but if the immune system doesn’t work well due to circadian misalignment, tumors might grow unchecked.
Our cellular clocks help coordinate important processes like cell division, DNA repair, and immune surveillance. When these clocks are disrupted, animal and cell studies show increased cancer cell growth and tumor progression. Human studies have also linked chronic circadian disruption, including shift work and nighttime light exposure, with higher cancer risk.
Researchers put healthy adults on recurring 28-hour days, causing their sleep and eating schedules to drift up to 12 hours out of sync with their internal clocks. At peak misalignment, glucose rose 6% despite insulin rising 22%, blood pressure increased, sleep efficiency fell 20%, and 3 of 8 participants developed post-meal glucose responses in the prediabetic or diabetic range.
Your body’s clocks need to be in sync for optimal health
All the clocks in the body are interconnected. For example, the stronger the SCN signal, the stronger the signal it can send to the peripheral clocks, thereby activating them as well, and keeping them in synchrony.3 For ideal health, you want all the clocks in your body to be in harmony with each other. They do not all perform the same activities at the same time, but they should be operating on roughly the same biological time.
Think of it like an orchestra. Every instrument plays a different part, but they all need to follow the same timing. When our clocks become misaligned, different parts of the body begin operating on different schedules, creating noise in the system.
For example, when light and food timing don’t work in harmony, you have different clocks in your body telling different times. Now imagine how much chaos that creates! If you had 5 different clocks in your house each one telling a different time, wouldn’t you be confused when going about your business? Multiply that by trillions of cells each having their own clocks and the amount of noise and disharmony that can result from different clock times. Each one marching to their own beat, not cooperating, creating noise in the body, oh boy that’s not a very well functioning system.
This idea of synchrony between the clocks often gets missed from circadian health advice. People focus on proper light exposure for a strong circadian signal. But circadian health is also about our different clocks being in synchrony with each other.
What did I do with this information?
I used to be Peter, thinking I was doing everything right for my health, and yet never felt the best. Then I turned into Tom, getting my circadian alignment in order, and had such high energy. For my sunrise to bedtime circadian alignment protocol, see:
The takeaway is that light, food, sleep and activity all send timing signals to our body. When those signals work together, different systems know when to be active, metabolize, grow, repair and rest. When they regularly conflict, the orchestra begins to fall out of sync.
And this brings us to one of the easiest ways we may be creating this misalignment every day: when we eat. In Part 2, I’ll explain why conventional intermittent fasting may be poor advice, and why skipping or delaying breakfast may in fact backfire.
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Related Posts:
https://pubmed.ncbi.nlm.nih.gov/26858430/
The suprachiasmatic nucleus (SCN) is a tiny region in the brain that acts as the body’s master circadian clock. It receives light signals from the eyes and uses them to help coordinate daily rhythms throughout the body.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11263371/