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Your 24-Hour Clock
The master clock in your brain
The suprachiasmatic nucleus (SCN) is a tiny cluster of ~20,000 neurons that orchestrates every system in your body on a 24-hour cycle.
20,000
neurons in the master clock
Fact
Light is the #1 signal
Special photoreceptors in your eyes (melanopsin cells) detect blue light and send timing signals directly to the SCN. No other signal is as powerful.
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Explore the daily rhythm
Tap each time of day to discover what your body is doing.
Tap each tile to reveal the detail.
True or false
True or False
Your circadian rhythm runs on exactly 24 hours.
The human circadian clock runs on exactly 24 hours
It's actually ~24.2 hours on average. Daily light exposure resets it to stay synchronized with the solar day.
Insight
Every organ has a clock
Your liver, heart, gut, and muscles all have their own peripheral clocks. When these desynchronize from the master clock, disease risk rises dramatically.
Takeaway
Key Takeaway
Your circadian rhythm controls hormones, metabolism, and immunity. Consistent light/dark patterns are the most important thing you can do for it.
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