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Chronobiology & Circadian Rhythms

Every cell in your body keeps time. A molecular negative-feedback loop — CLOCK, BMAL1, PER — ticks with a 24-hour period set before multicellular life existed.

6 simulations Circadian · Sleep ODE Models · Melatonin

Simulations

Open any simulation — runs instantly in your browser

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New★★☆ Moderate
Circadian Rhythm — 24-Hour Body Clock Simulator
Goodwin-oscillator approximation of melatonin, cortisol and core-temperature cycles over 24 hours. Adjust wake time, sleep time, light intensity, chronotype offset and jet-lag shift to explore phase-response dynamics.
GoodwinMelatoninCortisol
Popular★★★ Advanced
Circadian Oscillator — ODE Clock Model
Goldbeter's 5-variable ODE model of the CLOCK/BMAL1/PER feedback loop — a limit cycle oscillator producing a ~24 h period. Perturb with light pulses to see phase shifting.
ODELimit CycleCLOCK
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★★☆ Moderate
Two-Process Sleep Model
Borbély's homeostatic sleep pressure (Process S) rises during wake and decays during sleep, gated by the circadian oscillator (Process C). See how sleep deprivation shifts the balance.
BorbélySleepHomeostasis
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★★★ Advanced
Gene Expression Oscillator
Reaction-diffusion model of coupled oscillating gene networks — mRNA and protein concentrations cycle with the circadian period, coupling transcriptome-wide rhythms.
RDmRNAOscillator
✈️
★★☆ Moderate
Jet Lag — Phase Shift Dynamics
Transmeridian travel displaces the zeitgeber relative to the body clock. ODE model shows re-entrainment speed vs. travel direction — westward jet lag is easier than eastward, and why.
Phase ShiftEntrainmentODE
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★☆☆ Beginner
Seasonal Migration — Photoperiodism
Boid agents whose departure timing is governed by a day-length threshold. Vary latitude and climate shift — recreate phenological mismatch where birds arrive before peak caterpillar emergence.
BoidsPhotoperiodMigration
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★★☆ ModerateNew
Chronopharmacology — Drug Timing
Pharmacokinetic ODE model coupled to circadian absorption/metabolism rhythms. Vary dosing time to minimise side effects — the science behind why cancer drugs work better at certain hours.
PK/PDADMECircadian

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About Chronobiology Simulations

Circadian clocks, biological rhythms, and oscillating gene networks

Chronobiology simulations model the molecular and physiological oscillators that govern the daily timing of life. Circadian clock models simulate the transcription-translation feedback loop of clock genes (CLOCK, BMAL1, PER, CRY) as a system of coupled ordinary differential equations, reproducing the ~24 h period and how it entrains to light-dark cycles. Ultradian rhythm simulations model ultradian pulse generators for hormone secretion and sleep-stage cycling.

Phase-resetting curve simulations compute how light pulses of different timing shift the circadian phase — the mathematical basis of jet-lag recovery and shift-work scheduling strategies. Population models show the Kuramoto synchronisation of coupled cellular oscillators, explaining how a molecular clock in each cell drives organ-level rhythms. These models connect biochemistry to physiology and are used in chronopharmacology and sleep-medicine research.

Each simulation in this category is built with accuracy and interactivity in mind. The underlying mathematical models are the same ones used in academic research and professional engineering — just made accessible through a web browser. Changing parameters in real time and observing the results is one of the most effective ways to build intuition for complex scientific and engineering concepts.

Key Concepts

Topics and algorithms you'll explore in this category

Circadian ClockCLOCK/BMAL1 transcription-translation feedback loop
Two-Process SleepHomeostatic sleep pressure + circadian rhythm
Phase Response CurveLight-pulse phase shifts in the SCN oscillator
Melatonin DynamicsPineal secretion onset and morning suppression
Social JetlagMisalignment between biological and social time
EntrainmentHow external Zeitgebers reset internal oscillators

Frequently Asked Questions

Common questions about this simulation category

What is chronobiology and what can I simulate here?
Chronobiology studies biological time-keeping. These simulations cover the molecular CLOCK/BMAL1 feedback loop, the two-process model of sleep, melatonin dynamics, phase response curves, and circadian entrainment.
How is the circadian clock modelled mathematically?
The core model uses Leloup-Goldbeter ODE systems representing transcription, translation, phosphorylation, and nuclear transport of CLOCK and BMAL1 proteins — producing ~24 h oscillations.
Can I explore the effects of shift work or jet lag?
Yes — the social jetlag simulation lets you shift the light-dark cycle relative to the biological clock and observe the resulting misalignment and re-entrainment dynamics.