Circadian Rhythm Reset at Midnight — SCN Clock Cell (3D)

Light Exposure

Brightness 70%

Exposure duration 2.0 h

Time of exposure 23:00

Blue-light content 80%

Drag the 💡 on the mini timeline below the 3D view to move the light event. Orbit-drag / scroll the 3D scene to rotate and zoom the SCN cluster.

Your Clock

Usual bedtime 23:00

Clock Preview

Readout

Peak suppression

Phase shift

0.0 h

Direction

—

Est. CBTmin

—

The real biology

The glowing cluster is a stylized patch of the suprachiasmatic nucleus (SCN) — a few thousand neurons whose clock genes (Per/Cry-type transcription-translation feedback loops) cycle up and down roughly every 24 hours, and which synchronize with each other via cell-to-cell signaling. The colour pulse from indigo (low expression, subjective day) to warm amber (peak expression, night) tracks that gene-expression rhythm; a small phase jitter between neurons keeps the tissue looking alive rather than a single blinking light, as real SCN tissue is heterogeneous but coupled.

Light doesn't reach the SCN through rods or cones — melanopsin-containing retinal ganglion cells detect it (most sensitive to blue, ~480 nm) and signal the SCN directly via the retinohypothalamic tract, shown here as the bulb lighting the cluster. That input does two real things at once: it acutely suppresses downstream melatonin release (a saturating dose-response curve, stronger with more blue-rich, longer, brighter light), and it resets the clock's phase — but the direction of that reset flips depending on when the light lands relative to the body's core-temperature minimum (CBTmin ≈ bedtime + 6h): before it delays, after it advances. Toggle "Tomorrow (shifted)" to see the same cluster running one cycle later, on the clock your light event actually produced.

High clock-gene expression Low clock-gene expression

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